Citation: Luca, M.I.;

Ungureanu-Iuga, M.; Mironeasa, S.

Carrot Pomace Characterization for

Application in Cereal-Based Products.

Appl. Sci. 2022, 12, 7989. https://

doi.org/10.3390/app12167989

Academic Editor: Raffaella Boggia

Received: 5 July 2022

Accepted: 8 August 2022

Published: 10 August 2022

Publisher’s Note: MDPI stays neutral

with regard to jurisdictional claims in

published maps and institutional affil-

iations.

Copyright: © 2022 by the authors.

Licensee MDPI, Basel, Switzerland.

This article is an open access article

distributed under the terms and

conditions of the Creative Commons

Attribution (CC BY) license (https://

creativecommons.org/licenses/by/

4.0/).

applied sciences

Article

Carrot Pomace Characterization for Application inCereal-Based ProductsMarian Ilie Luca 1, Mădălina Ungureanu-Iuga 1,2 and Silvia Mironeasa 1,*

1 Faculty of Food Engineering, Stefan cel Mare University of Suceava, 13 Universitatii Street,720229 Suceava, Romania

2 Integrated Center for Research, Development and Innovation in Advanced Materials, Nanotechnologies,and Distributed Systems for Fabrication and Control (MANSiD), Stefan cel Mare University of Suceava,13th University Street, 720229 Suceava, Romania

* Correspondence: silviam@fia.usv.ro

Abstract: Carrot is one of the most consumed vegetables worldwide and the production of juicesgenerates high amounts of valuable by-products such as pomace. In order to minimize the en-vironmental effects and to optimize the production costs, carrot pomace can be considered as aningredient in various food products. The aim of this study was to characterize carrot pomace powdersfrom four varieties (Baltimore, Niagara, Belgrado, and Sirkana) and, from a chemical, functional,chromatic, microstructural, and molecular point of view, highlight the possibility of using them asfood ingredients. The results obtained showed that the chemical composition, functional properties,color, and molecular structures of carrot pomace powders depend on the variety. Carrot pomacepowders had high contents of fibers (20.09–33.34%), carbohydrates (46.55–58.95%), ash (5.29–5.89%),and proteins (6.87–9.14%), with the Belgrado variety being the richest in fibers and ash, while theSirkana variety had the greatest protein and the smallest carbohydrate content. With respect to thefunctional properties, significant differences among the samples were recorded for water absorptionand retention capacities, with the Baltimore carrot pomace presenting the highest values (16.99%and 7.64 g/g, respectively). All of the samples exhibited high foaming stability (FS > 94%), with thehydration capacity being higher than 57.96%, the oil absorption capacity being greater than 34.33%,and the bulk density comprised between 0.45 and 0.56 g/cm3. The highest luminosity was obtainedfor the Baltimore sample (73.30), while the Niagara variety exhibited the most yellowish (19.61),reddish (13.05), and intense (23.55) color. The microstructure of all the samples were compact, whilethe FT-IR spectra depicted the presence of beta carotene, fibers, carbohydrates, lipids, and proteins.These results could be helpful for processors and researchers interested in reducing their carbon footprint in the fruit processing industry and/or in creating food products with enriched nutritional andfunctional values.

Keywords: by-product valorization; carrot pomace; functional properties; physico-chemical properties;FT-IR; micrographs

1. Introduction

The food industry is constantly evolving, as evidenced by the appearance on themarket of new products, enriched with ingredients that bring benefits to the health ofconsumers. The addition of various by-products in foods can provide both a viable eco-nomic solution through their use, and a substantial health aid through their nutritional andfunctional value. During carrot juice production, up to 50% of the roots result in pomacewhich is usually employed as feed or manure [1].

Medical studies have shown that the consumption of both fruits and vegetables bringsimportant benefits to the health of consumers by reducing the risk of coronary heartdisease and heart attacks, but also various types of cancer [2]. In addition to dietary fiber,organic micronutrients such as carotenoids, polyphenols, tocopherols, vitamin C, and

Appl. Sci. 2022, 12, 7989. https://doi.org/10.3390/app12167989 https://www.mdpi.com/journal/applsci

Appl. Sci. 2022, 12, 7989 2 of 15

many other vitamins also add value to food products which can contribute to humanhealth [2]. The carrot (Daucus carota) is a root vegetable consumed worldwide, its colorvarying from orange, red, purple, white, and yellow. It is an important source of bioactivecompounds such as dietary fibers and carotenoids, but also other functional groups whereinsignificant health benefits are to be found. One of the most important bioactive compoundsis represented by β-carotene and vitamins (thiamine, riboflavin, folic acid, and vitamin B-complex) and minerals (calcium, copper, magnesium, potassium, phosphorus, and iron) [3].

A significant number of by-products is produced in the food industry, and theircorrect disposal is crucial in order to reduce environmental pollution. On the other hand,these residual components contain significant amounts of polysaccharides, polyphenols,carotenoids, and other functional components that could be retrieved and then reused in theproduction of functional foods [4]. Some data reported in the literature on the compositionof trace elements in dried pomace revealed that carrot pomace contains the followingtrace elements (mg/kg): sodium (3.2), potassium (18.6), phosphorous (1.8), calcium (3.0),magnesium (1.1), copper (4.0), manganese (10.8), iron (30.5), and zinc (29.4) [5]. Nawirskaand Kwasniewska [6] found that the main types of fiber found in the composition ofcarrot pomace are pectin (3.88%), hemicellulose (12.3%), cellulose (51.6%), and lignin(32.1%). Thus, the carrot by-product after juice extraction resulted in a promising source ofphytochemicals with many health benefits that could be considered in the development ofvegetal ingredients for the food industry and for dietary supplements [7]. Adding value toby-products helps to lower the price of the main product, thus leading to a direct profit forprocessors and consumers.

The proximate composition, physical properties, and functional characteristics ofcarrot pomace are influenced by the processing methods used. The chemical composition,color parameters, and water-holding capacity of carrot pulp were affected by blanchingaccording to the data reported by Bao and Chang [8]. Carrot pomace dried convectivelywas recommended by Alam et al. [3] since the quality attributes recorded greater fiber, totalcarotenoids, β-carotene contents, and low modifications in color parameters compared toother treatments. The content of protein, reducing sugars, minerals, and fibers of carrotpomace vary from 4–5%, 8–9%, 5–6%, and 37–48%, respectively, and its use in food productfortification led to increases in dietary fiber [1].

The papers found in the literature revealed the possibility to valorize carrot pomacein different ways. Tanska et al. [5] demonstrated that carrot pomace can be incorporatedinto wheat bread by replacing wheat flour up to 5% when the final product presented thebest quality parameters. Singh et al. [9] showed that carrot pomace can be used to preparea carrot-based condensed milk product called “gazrella” which kept reasonable overallacceptability scores even after 6 months of depositing at room temperature. Kırbas et al. [10]obtained gluten-free cake with enhanced fiber content by adding carrot pomace, with thefinal product presenting acceptable sensory characteristics. Another study conducted byShiraz et al. [11] revealed that carrot pomace can be employed in the production of highfiber ready-to-eat expanded snacks from barley flour, with up to 10% addition being theoptimum dose recommended by the authors.

The aim of the present study was to investigate four varieties of carrot pomace floursin terms of functionality, chemical composition, and microstructural and molecular charac-teristics. For this purpose, the proximate composition of flours was determined along withthe molecular conformations, functional properties, color, and microstructure in order tohighlight some possible uses of carrot pomace in order to create value-added products.

2. Materials and Methods2.1. Materials

Four varieties of carrots (Niagara, Belgrado, Sirkana, and Baltimore) were purchasedfrom a farmer in Bacau, Romania. The carrot pomace was obtained by extracting the carrotjuice with a Bosch MES3500 (Philips Consumer Lifestyle B.V., Drachten, Holland) device.The drying treatment of carrot pomace was performed in a convector with hot air at a

Appl. Sci. 2022, 12, 7989 3 of 15

temperature of 60 ◦C for 24 h and a layer thickness of 0.5 cm. After drying, the resultingcarrot pomace was ground using a grinding machine for 30 s. In order to obtain a particlesize smaller than 200 µm, the whole carrot flour was sieved in a Retsch Vibratory SieveShaker AS 200 basic (Retsch GmbH, Haan, Germany) device. Carrot flours were kept indark glass bottles until analysis.

2.2. Chemical Properties

The chemical properties (moisture, protein, fat, and ash) of carrot pomace powder wereanalyzed using International Association for Cereal Chemistry (ICC) methods: moisture(101/1), fat (104/1), protein (105/2), and ash (105/1). The amount of total dietary fiber wasevaluated by using a Megazyme kit K-TDFR-200a 04/17 (Megazyme Ltd., County Wicklow,Ireland) in agreement with the American Association of Cereal Chemists (AACC) 32-05.01protocol. The carbohydrate content was calculated by difference, by applying the equation(Equation (1)) used by Cotovanu et al. [12]. The determinations were made in duplicate(n = 2).

Carbohydrates (%) = 100 − (protein + fat + ash + fiber + moisture) (1)

The energetic value (kcal/100 g) of the samples was also calculated by multiplyingthe nutrient’s values by their corresponding conversion coefficients Equation (2):

Energy (kcal/100 g) = (4 × protein) + (9 × fat) + (4 × carbohydrates) + (2 × fiber) (2)

2.3. Functional Properties of Carrot Pomace Powder2.3.1. Hydration Capacity (HC)

The hydration capacity was determined in duplicate (n = 2), in agreement with theprotocol proposed by Bordei et al. [13] with modifications. An amount of 2.5 g of thesample was taken for analysis and placed in a 50 mL tube, where 15 mL of water wasadded. Within 1 h, the sample was mixed with a rod for 30 s every 10 min. The stem waswashed with 10 mL of water and the resulting suspension was centrifuged for 20 min at3000 rpm. After removing the supernatant, the sample was kept at a temperature of 50 ◦Cfor 25 min and after cooling it was weighed. The hydration capacity was calculated usingthe Equation (3):

HC (%) =(m2 − mo)− m1

m1× 100 (3)

where:mo—weight of the tube;m1—weight of sample taken into analysis;m2—weight of sample which absorbed water.

2.3.2. Water Absorption Capacity (WAC)

The water absorption capacity was determined (n = 2) by the method proposed byOladiran and Emmambux [14] with modifications. The sample (1 g) was placed in acentrifuge tube with 10 mL of distilled water. The sample was kept in a water bath withcontinuous mixing for 30 min at 30 ◦C and then centrifuged for 15 min at 3500 rpm. Thesupernatant was removed and the residue was weighed. The results were calculated usingthe Equation (4):

WAC (%) =m1

mo× 100 (4)

where:mo—weight of sample taken into analysis;m1—weight of sample after supernatant removal.

Appl. Sci. 2022, 12, 7989 4 of 15

2.3.3. Oil Absorption Capacity (OAC)

Oil absorption capacity was determined in duplicate (n = 2) according to the methodproposed by Elkhalifa and Bernhardt [15] with modifications. The sample of carrot pomacepowder in a quantity of 1 g was placed in a centrifuge tube with 10 mL of sunfloweroil. The sample taken for analysis was stirred for 1 min every 10 min for 30 min. Aftercentrifugation at 3000 rpm for 15 min, the supernatant was decanted and the tubes wereallowed to drain for 5 min, and then the residue was weighed. The result was calculated byusing the Equation (5):

OAC (%) =m1

mo× 100 (5)

where:mo—weight of sample taken into analysis;m1—weight of sample after supernatant removal.

2.3.4. Swelling Capacity (SC)

Swelling capacity was determined (n = 2) using the method of Raghavendra et al. [16]with modifications. For this purpose, 25 mL of deionized water put in a 50 mL graduatedcylinder, which was covered with aluminum foil to prevent evaporation, was added to thesample of carrot pomace powder (1 g). The sample was stored at room temperature for24 h. After 24 h, the sample volume was measured and expressed as mL of water on thecarrot pomace powder Equation (6).

SC(

mLg

)=

Volume occupied by sampleOriginal sample weight

(6)

2.3.5. Water Retention Capacity (WRC)

Water retention capacity (WRC) was determined in duplicate (n = 2) according to themethod proposed by Raghavendra et al. [16] with modifications. An amount of 1 g ofcarrot pomace powder was placed in a centrifuge tube with 30 mL of distilled water. After24 h, the sample was centrifuged at 3000 rpm for 20 min and the supernatant was removed.The sample was dried for 2 h at 105 ◦C in a convection oven. The results expressed as anaverage of two determinations were calculated with Equation (7):

WRC (g/g) =m1 − m2

m2(7)

where:m1—residue hydrated weight;m2—residue dry weight.

2.3.6. Foaming Capacity (FC) and Foaming Stability (FS)

Foaming capacity and stability were determined (n = 2) according to the methodsproposed by Elkhalifa and Bernhardt [15]. For this purpose, 2 g of sample and 100 mLof distilled water were placed in a 500 mL beaker, the suspension was mixed with ablender at room temperature for 1 min. The contents were immediately moved to a 250 mLgraduated cylinder and the foam volume was measured. The results were calculated usingthe Equation (8):

FC (%) =volume a f ter whipping − volume be f ore whipping

volume be f ore whipping× 100 (8)

Foam stability was determined by following the decrease in foam volume every 10 minfor 1 h and using the Equation (9):

FS (%) =Foam volume a f ter set o f time

Initial f oam volume× 100 (9)

Appl. Sci. 2022, 12, 7989 5 of 15

2.3.7. Bulk Density (BD)

Bulk density was measured (n = 2) according to the procedure presented by Okakaand Potter [17] with modification. The carrot pomace powder (5 g) was put into a 50 mLgraded cylinder and tapped 20–30 times. The bulk density was calculated as weight perunit volume of sample.

2.4. FT-IR Spectra

FT-IR spectra used for the molecular characterization of carrot pomace flours werecollected three times (n = 3) for each sample in the range of 650 to 4000 cm−1 by using aThermo Scientific Nicolet iS20 (Waltham, MA, USA) apparatus at a resolution of 4 cm−1 by32 scans. Average spectra were obtained on the Omnic software.

2.5. SEM Micrographs

SEM micrographs of carrot pomace flours were obtained by using a VEGA II LSHscanning electronic microscope (Tescan, Brno, Czech Republic). The acceleration tensionused in the experiments was 30 kV and the magnifications were 100×, 500×, and 1000×.Carbon adhesive bands were used to fix the powders.

2.6. Carrot Pomace Powder Color

The color parameters of carrot pomace powder were measured (n = 3) by reflectance,in the CIE Lab system on a Konica Minolta CR-400 (Konica Minolta, Tokyo, Japan) device.Triplicate determinations were performed.

2.7. Statistics

All of the measurements were performed at least in duplicate (n ≥ 2). Statisticalprocessing of data was performed on XLSTAT for Excel 2021 version (Addinsoft, New York,NY, USA) software. One-Way ANOVA with Tukey test was used to evaluate the differencesamong samples, the confidence level was considered, being 95%.

Principal Component Analysis (PCA) was applied to investigate the relationshipsbetween variables. The number of factors was established at 2, with a varimax rotationmethod and n data standardization being applied.

3. Results3.1. Carrot Pomace Powder of Different Varieties Chemical Properties

The chemical composition of carrot pomace powders is presented in Table 1. Significantdifferences (p < 0.05) between the analyzed carrot pomace varieties were observed regardingthe fat, ash, fiber, and carbohydrates values.

Table 1. Chemical composition of carrot pomace powders.

Variety Protein (%) Fat (%) Ash (%) Fiber (%) Moisture (%) Carbohydrates(%)

Energetic Value(kcal/100 g)

Baltimore 6.87 ± 0.06 c 1.00 ± 0.02 b 5.29 ± 0.04 c 28.69 ± 0.58 c 4.04 ± 0.02 b 54.13 ± 0.52 b 339.40 ± 40.18 b

Belgrado 8.01 ± 0.06 b 1.01 ± 0.03 b 5.89 ± 0.02 a 33.34 ± 0.25 a 3.78 ± 0.01 b 48.00 ± 0.24 c 333.96 ± 47.87 b

Niagara 8.84 ± 0.12 a 0.70 ± 0.02 c 5.56 ± 0.03 b 20.09 ± 0.08 d 5.88 ± 0.46 a 58.95 ± 0.65 a 343.32 ± 34.64 a

Sirkana 9.14 ± 0.06 a 1.13 ± 0.03 a 5.89 ± 0.01 a 31.40 ± 0.70 b 5.91 ± 0.15 a 46.55 ± 0.64 c 332.00 ± 35.81 b

Mean values (n = 2) followed by different superscripts in the same column are significantly different betweenvarieties (p < 0.05).

The Niagara variety presented the highest content of carbohydrates and the lowest fatand fiber content compared to the other varieties. The Belgrado carrot pomace showed thegreatest fiber content and the smallest moisture. The richest in fat, protein, and ash contentswas the Sirkana carrot pomace with this variety having the lowest carbohydrates content.

Appl. Sci. 2022, 12, 7989 6 of 15

The Baltimore variety presented the lowest ash content. With respect to the energetic value,only Niagara exhibited a significantly higher value compared to the other varieties.

3.2. Carrot Pomace Powder of Different Varieties Functional Properties and Color

The functional properties of carrot pomace powders varied slightly depending onthe variety (Table 2). No significant differences (p > 0.05) among samples were obtainedfor HC, except for the Niagara sample which was different from the other samples, whileBaltimore and Sirkana showed significant differences (p < 0.05). Regarding OAC, Baltimoreregistered the highest OAC. Regarding WAC, the values varied from 11.59% for Niagara to16.99% for the Baltimore pomace, while the WRC comprised between 4.76 g/g for Niagaraand 7.62 g/g for the Baltimore sample. The Baltimore and Sirkana carrot pomaces had thelowest FC compared to the other varieties, but the stability was superior. The Baltimoreand Sirkana samples exhibited the highest BD, while Niagara had the biggest SC.

Table 2. Functional properties of carrot pomace powders.

Variety HC (%) WAC (%) OAC (%) WRC (g/g) FC (%) FS (%) SC (mL/g) BD (g/cm3)

Baltimore 67.94 ± 2.67 a 16.99 ± 0.24 a 37.31 ± 0.32 a 7.64 ± 0.03 a 5.00 ± 0.00 b 96.00 ± 0.00 a 25.95 ± 0.01 b 0.56 ± 0.00 a

Belgrado 66.81 ± 2.24 a 15.96 ± 0.44 ab 34.72 ± 0.85 c 5.33 ± 0.05 c 7.00 ± 0.00 a 94.00 ± 0.00 b 25.96 ± 0.01 b 0.46 ± 0.00 b

Niagara 57.96 ± 0.78 b 11.59 ± 0.01 c 34.33 ± 0.25 c 4.76 ± 0.01 d 7.00 ± 0.00 a 94.00 ± 0.00 b 27.22 ± 0.00 a 0.45 ± 0.00 b

Sirkana 68.26 ± 4.51 a 15.15 ± 0.37 b 35.29 ± 1.68 b 6.10 ± 0.00 b 5.00 ± 0.00 b 96.00 ± 0.00 a 27.20 ± 0.01 a 0.56 ± 0.00 a

HC—hydration capacity, WAC—water absorption capacity, OAC—oil absorption capacity, WRC—water retentioncapacity, FC—foaming capacity, FS—foaming stability, SC—swelling capacity, and BD—bulk density. Meanvalues (n = 2) followed by different superscripts in the same column are significantly different between varieties(p < 0.05).

The color parameters of carrot pomace varied in function of variety, especially theluminosity (L*), the red nuance suggested by the positive values of a*, and the color intensity(C *)as is shown in Table 3. The luminosity varied from 66.02 for the Niagara sample to73.30 for the Baltimore sample. The most pronounced red nuance was observed in the caseof the Niagara variety, while Baltimore presented the lowest value for a*. All of the studiedsamples had a yellow nuance because the values of b* parameters were positive, but nosignificant differences (p > 0.05) were observed between varieties, except for Baltimorewhich had the lowest value. The highest color intensity was obtained for the Niagarasample, while Baltimore had the smallest value.

Table 3. Color CIE Lab parameters of carrot pomace powders.

Variety L* (Adim.) a* (Adim.) b* (Adim.) C* (Adim.)

Baltimore 73.30 ± 0.15 a 8.61 ± 1.68 b 18.85 ± 0.16 b 20.77 ± 0.62 c

Belgrado 71.30 ± 0.09 b 10.21 ± 0.15 b 19.47 ± 0.05 a 21.98 ± 0.10 b

Niagara 66.02 ± 0.08 d 13.05 ± 0.02 a 19.61 ± 0.06 a 23.55 ± 0.04 a

Sirkana 69.44 ± 0.01 c 9.25 ± 0.06 b 19.56 ± 0.04 a 21.63 ± 0.05 a

Means (n = 3) followed by different superscripts in the same column are significantly different between varieties(p < 0.05).

3.3. Carrot Pomace Powder of Different Varieties Micrographs

The microstructure of carrot pomace powders at different magnifications is presentedin Figure 1. SEM micrographs of carrot pomace from different varieties exhibited regularcompact cellular network. Similar structure of carrot tissues was reported in previousworks [18,19]. Fibrous structures can be depicted for all the analyzed samples.

Appl. Sci. 2022, 12, 7989 7 of 15

Appl. Sci. 2022, 12, x FOR PEER REVIEW 7 of 15

3.3. Carrot Pomace Powder of Different Varieties Micrographs The microstructure of carrot pomace powders at different magnifications is pre-

sented in Figure 1. SEM micrographs of carrot pomace from different varieties exhibited regular compact cellular network. Similar structure of carrot tissues was reported in pre-vious works [18,19]. Fibrous structures can be depicted for all the analyzed samples.

(a1) (a2) (a3)

(b1) (b2) (b3)

(c1) (c2) (c3)

Figure 1. Cont.

Appl. Sci. 2022, 12, 7989 8 of 15Appl. Sci. 2022, 12, x FOR PEER REVIEW 8 of 15

(d1) (d2) (d3)

Figure 1. SEM micrographs of carrot pomace powders of Baltimore (a), Belgrado (b), Niagara (c), and Sirkana (d) varieties at 100× (1), 500× (2), and 1000× (3) magnification. The regions enlarged are marked with a yellow border.

3.4. Carrot Pomace Powder of Different Varieties FT-IR Spectra FT-IR spectra of carrot pomace powders revealed the presence of bioactive com-

pounds, with some differences regarding peak intensities being observed among the sam-ples (Figure 2). The highest absorbances were obtained for the Niagara sample, followed in decreasing order by Sirkana, Baltimore, and Belgrado, except in the regions 1510–2325 cm−1 and 2898–2939 cm−1. The Niagara and Baltimore varieties presented the highest peaks at 1736 cm−1 which may be associated with the presence of beta-carotene [20], while in the region 1550–1650 cm−1, which could depict the presence of pectin [21], Niagara recorded higher intensities. The presence of galacturonic acid in all of the analyzed samples was suggested by the appearance of peaks at 2898 and 1606 cm−1, with the Niagara variety exhibiting different peaks in the region 2898–2938 cm−1 compared to the other samples. The peaks found at 1421, 1367, 1104, and 1032 cm−1 could be related to cellulose [22], with the Niagara sample showing the biggest intensities, while the lowest were observed for the Belgrado variety. The peaks at 1649 and 1557 cm−1 can be attributed to the presence of proteins in the carrot pomace powders.

(a)

Figure 1. SEM micrographs of carrot pomace powders of Baltimore (a), Belgrado (b), Niagara (c),and Sirkana (d) varieties at 100× (1), 500× (2), and 1000× (3) magnification. The regions enlarged aremarked with a yellow border.

3.4. Carrot Pomace Powder of Different Varieties FT-IR Spectra

FT-IR spectra of carrot pomace powders revealed the presence of bioactive com-pounds, with some differences regarding peak intensities being observed among the sam-ples (Figure 2). The highest absorbances were obtained for the Niagara sample, followed indecreasing order by Sirkana, Baltimore, and Belgrado, except in the regions 1510–2325 cm−1

and 2898–2939 cm−1. The Niagara and Baltimore varieties presented the highest peaks at1736 cm−1 which may be associated with the presence of beta-carotene [20], while in theregion 1550–1650 cm−1, which could depict the presence of pectin [21], Niagara recordedhigher intensities. The presence of galacturonic acid in all of the analyzed samples wassuggested by the appearance of peaks at 2898 and 1606 cm−1, with the Niagara varietyexhibiting different peaks in the region 2898–2938 cm−1 compared to the other samples.The peaks found at 1421, 1367, 1104, and 1032 cm−1 could be related to cellulose [22], withthe Niagara sample showing the biggest intensities, while the lowest were observed forthe Belgrado variety. The peaks at 1649 and 1557 cm−1 can be attributed to the presence ofproteins in the carrot pomace powders.

Appl. Sci. 2022, 12, x FOR PEER REVIEW 8 of 15

(d1) (d2) (d3)

Figure 1. SEM micrographs of carrot pomace powders of Baltimore (a), Belgrado (b), Niagara (c), and Sirkana (d) varieties at 100× (1), 500× (2), and 1000× (3) magnification. The regions enlarged are marked with a yellow border.

3.4. Carrot Pomace Powder of Different Varieties FT-IR Spectra FT-IR spectra of carrot pomace powders revealed the presence of bioactive com-

pounds, with some differences regarding peak intensities being observed among the sam-ples (Figure 2). The highest absorbances were obtained for the Niagara sample, followed in decreasing order by Sirkana, Baltimore, and Belgrado, except in the regions 1510–2325 cm−1 and 2898–2939 cm−1. The Niagara and Baltimore varieties presented the highest peaks at 1736 cm−1 which may be associated with the presence of beta-carotene [20], while in the region 1550–1650 cm−1, which could depict the presence of pectin [21], Niagara recorded higher intensities. The presence of galacturonic acid in all of the analyzed samples was suggested by the appearance of peaks at 2898 and 1606 cm−1, with the Niagara variety exhibiting different peaks in the region 2898–2938 cm−1 compared to the other samples. The peaks found at 1421, 1367, 1104, and 1032 cm−1 could be related to cellulose [22], with the Niagara sample showing the biggest intensities, while the lowest were observed for the Belgrado variety. The peaks at 1649 and 1557 cm−1 can be attributed to the presence of proteins in the carrot pomace powders.

(a)

Figure 2. Cont.

Appl. Sci. 2022, 12, 7989 9 of 15Appl. Sci. 2022, 12, x FOR PEER REVIEW 9 of 15

(b)

Figure 2. FT-IR spectra of carrot pomace powders: (a) in the range 650–4000 cm−1, and (b) in the range 1450–1750 cm−1.

3.5. Relationships between Characteristics Principal Component Analysis (PCA) (Figure 3) allowed for the interpretation of the

relationships between variables, based on correlations. The first principal component (PC1) explained 45.91% of the total variance, while the second one (PC2) explained 38.38% of the data variance. The highest contributions on PC1 were observed for protein (9.68%), ash (6.53%), b* (11,44%), SC (5.40%), and moisture (4.26%). Other parameters that contrib-ute to PC1 were OAC (10.70%) and WRC (10.05%) which were in opposition to the protein content and b* parameter. Regarding PC2, it was observed that fat (12.69%), fiber (11.61%), carbohydrates (13.31%), energetic value (13.33%), and HC (10.30%) had a high contribu-tion. The PC1 highlights an opposition between fat, HC and carbohydrates, energetic value, and between ash and FC, C*. PC2 distinguished between WAC and FC, fiber and a*, BD and a*, while L* was in opposition with FC and C*, and OAC was opposed to SC and moisture (Figure 3). The Sirkana and Belgrado samples were associated with PC2, with an opposition between these two varieties with Niagara being observed. PC2 clearly distinguished between the Niagara and Baltimore varieties, with Baltimore being associ-ated with the OAC and WRC.

The fat content was significantly correlated (p < 0.05, r = 0.96) with HC, while the moisture content was strongly correlated (p < 0.05, r = 0.99) to SC. The energetic value was positively correlated (p < 0.05, r = 0.99) with the carbohydrates content. Significant nega-tive correlation was observed between HC and a* (p < 0.05, r = −0.97), while WAC was positively correlated with L* (p < 0.05, r = 0.98) and negatively with C* (p < 0.05, r = −0.96). A strong and positive relationship was obtained for OAC with WRC (p < 0.05, r = 0.99) and negative with b* parameter (p < 0.05, r = −0.95). FC and FS were significantly (p < 0.05, r = −0.99, and r = 0.99, respectively) correlated with BD.

Figure 2. FT-IR spectra of carrot pomace powders: (a) in the range 650–4000 cm−1, and (b) in therange 1450–1750 cm−1.

3.5. Relationships between Characteristics

Principal Component Analysis (PCA) (Figure 3) allowed for the interpretation of therelationships between variables, based on correlations. The first principal component (PC1)explained 45.91% of the total variance, while the second one (PC2) explained 38.38% of thedata variance. The highest contributions on PC1 were observed for protein (9.68%), ash(6.53%), b* (11,44%), SC (5.40%), and moisture (4.26%). Other parameters that contributeto PC1 were OAC (10.70%) and WRC (10.05%) which were in opposition to the proteincontent and b* parameter. Regarding PC2, it was observed that fat (12.69%), fiber (11.61%),carbohydrates (13.31%), energetic value (13.33%), and HC (10.30%) had a high contribution.The PC1 highlights an opposition between fat, HC and carbohydrates, energetic value, andbetween ash and FC, C*. PC2 distinguished between WAC and FC, fiber and a*, BD and a*,while L* was in opposition with FC and C*, and OAC was opposed to SC and moisture(Figure 3). The Sirkana and Belgrado samples were associated with PC2, with an oppositionbetween these two varieties with Niagara being observed. PC2 clearly distinguishedbetween the Niagara and Baltimore varieties, with Baltimore being associated with theOAC and WRC.

The fat content was significantly correlated (p < 0.05, r = 0.96) with HC, while themoisture content was strongly correlated (p < 0.05, r = 0.99) to SC. The energetic valuewas positively correlated (p < 0.05, r = 0.99) with the carbohydrates content. Significantnegative correlation was observed between HC and a* (p < 0.05, r = −0.97), while WAC waspositively correlated with L* (p < 0.05, r = 0.98) and negatively with C* (p < 0.05, r = −0.96).A strong and positive relationship was obtained for OAC with WRC (p < 0.05, r = 0.99) andnegative with b* parameter (p < 0.05, r = −0.95). FC and FS were significantly (p < 0.05,r = −0.99, and r = 0.99, respectively) correlated with BD.

Appl. Sci. 2022, 12, 7989 10 of 15Appl. Sci. 2022, 12, x FOR PEER REVIEW 10 of 15

Figure 3. Principal component Analysis (PCA) bi-plot: HC—hydration capacity, WAC—water ab-sorption capacity, WRC – water retention capacity, OAC—oil absorption capacity, FC—foaming capacity, FS—foaming stability, SC—swelling capacity, and BD—bulk density. Samples are marked with triangles and variables with bullets.

4. Discussion The results obtained for the chemical composition of carrot pomaces demonstrated

that they are an important source of fibers and carbohydrates, also providing an intake of proteins and minerals. The higher intake of fiber and total minerals would be given by the consumption of the Belgrado carrot pomace, while the Sirkana pomace presents the great-est protein level and the lowest carbohydrate content (Table 1). Kumari and Grewal [23] also reported the high amounts of ash and dietary fibers of carrot pomace used as an in-gredient in biscuits, which resulted in the improvement of the final product’s mineral and fiber profile. The literature stated that carrot pomace may contain between 4% and 5% protein, 5% and 6% minerals, and 37% to 48% total dietary fiber, which is in agreement with the results obtained in the present study (Table 1). Fibers are considered complex carbohydrates present in the structural components of plants that cannot be soaked up by the body and have many health benefits such as prevention of constipation, control of blood sugar, heart disease prevention, and the inhibition of certain types of cancers [1]. The main components of total fibers in carrot pomace are represented by pectin, cellulose, lignin, and hemicellulose [1]. Tańska et al. [5] demonstrated that the dried carrot pomace is a rich source of organic compounds, mainly polysaccharides. The authors reported a total carbohydrates content higher than 50% which was in agreement with our results (Table 1), affirming at the same time that high amounts of monosaccharides could have positive effects on bread made with wheat flour with low amylase activity because they represent an important source of carbon for yeast multiplication [5]. The content of lipids considered as natural solvents for carotenoids and the fount of some important unsatu-rated fatty acids was reported as being 6.0% [5], which was higher than the results of the present study (0.70–1.13%). The same authors stated that the dried carrot pomace also presented 5.5% mineral components, which can improve and supplement wheat bread mineral content [5].

The functional properties of carrot pomaces recorded some differences among sam-ples, depending on the variety. The presence of lipids and dietary fiber has an essential role in determining carrot pomace hydration characteristics such as water-holding, water

Figure 3. Principal component Analysis (PCA) bi-plot: HC—hydration capacity, WAC—waterabsorption capacity, WRC—water retention capacity, OAC—oil absorption capacity, FC—foamingcapacity, FS—foaming stability, SC—swelling capacity, and BD—bulk density. Samples are markedwith triangles and variables with bullets.

4. Discussion

The results obtained for the chemical composition of carrot pomaces demonstratedthat they are an important source of fibers and carbohydrates, also providing an intakeof proteins and minerals. The higher intake of fiber and total minerals would be givenby the consumption of the Belgrado carrot pomace, while the Sirkana pomace presentsthe greatest protein level and the lowest carbohydrate content (Table 1). Kumari andGrewal [23] also reported the high amounts of ash and dietary fibers of carrot pomaceused as an ingredient in biscuits, which resulted in the improvement of the final product’smineral and fiber profile. The literature stated that carrot pomace may contain between4% and 5% protein, 5% and 6% minerals, and 37% to 48% total dietary fiber, which is inagreement with the results obtained in the present study (Table 1). Fibers are consideredcomplex carbohydrates present in the structural components of plants that cannot be soakedup by the body and have many health benefits such as prevention of constipation, controlof blood sugar, heart disease prevention, and the inhibition of certain types of cancers [1].The main components of total fibers in carrot pomace are represented by pectin, cellulose,lignin, and hemicellulose [1]. Tanska et al. [5] demonstrated that the dried carrot pomace isa rich source of organic compounds, mainly polysaccharides. The authors reported a totalcarbohydrates content higher than 50% which was in agreement with our results (Table 1),affirming at the same time that high amounts of monosaccharides could have positiveeffects on bread made with wheat flour with low amylase activity because they representan important source of carbon for yeast multiplication [5]. The content of lipids consideredas natural solvents for carotenoids and the fount of some important unsaturated fatty acidswas reported as being 6.0% [5], which was higher than the results of the present study(0.70–1.13%). The same authors stated that the dried carrot pomace also presented 5.5%mineral components, which can improve and supplement wheat bread mineral content [5].

The functional properties of carrot pomaces recorded some differences among samples,depending on the variety. The presence of lipids and dietary fiber has an essential role indetermining carrot pomace hydration characteristics such as water-holding, water retention,and swelling capacities [16]. These statements are also supported by the high correlation

Appl. Sci. 2022, 12, 7989 11 of 15

obtained between HC and fat content. In agreement with the data presented in Table 2,carrot pomace powders had high SC (25.95–27.22 mL/g), comparable to those reported byRaghavendra et al. [16] for coconut residue, highlighting that carrot pomace has a greatability to swell, this being the most desirable property for the physical functionality ofdietary fiber. According to the data reported by Amin et al. [24], the SC of carrot waste was29.23 mL/g which was close to the values obtained in the present study (25.95–27.22 mL/g,Table 2). SC is directly influenced by the fiber content and soluble dietary fiber which playsan essential role in the functionality of the material because pectin and gums have a greaterwater-holding capacity than cellulose fibers [25]. Water retention capacity (WRC) is definedas the “ability of a matrix of molecules, usually macromolecules at low concentrations,to physically entrap certain amounts of water under the application of an external orgravitational force” [24,26]. WRC depends on the fiber dimension, being known thatgrinding can damage the fiber structure and lower its ability to trap water [24]. The porousmatrix composed of polysaccharide chains in plants holds high amounts of water by meansof hydrogen bonds, thereby offering beneficial functionality to vegetal materials [25]. Themain factors influencing the functionality of these polysaccharide chains are the proportionof insoluble to soluble dietary fiber and the dimension of product fraction [27]. Carrotsare an important source of soluble fibers such as pectin, which have a higher WRC thaninsoluble fibers, and could explain the high WRC in carrot fibers. The dietary fiber contentof coconut by-products after extraction of coconut milk was reported as being 60.21%, whichwas higher than that of the carrot pomace powders in the present study (20.09–33.34%), butwas comparable with those reported for orange by-product (20.01%) [16]. However, WRCof coconut pomace (5.4 g/g) was close to those obtained in the present study (4.76–7.64 g/g,Table 2) according to the data presented by Raghavendra et al. [16]. The WRC of coconutpomace was greater than that of other dietary fiber wastes such as potato, pea, and wheatbran fibers [16]. These results suggest that the carrot pomace could provide benefits similarto those of coconut pomace, which would be superior to potato, pea, or wheat bran fiber.Carrot pomace OAC was comprised between 34.33% and 37.31% with small differencesamong varieties. The OAC depends on many factors such as plant polysaccharides, density,hydrophobic particle character, particle size, and the amount of insoluble dietary fiber [25].Fibers present in carrot pomace could have the ability to stabilize food emulsions with agreat fat content [24], which supports the results of the present study. SC is defined as “theratio of the volume occupied when the sample is immersed in excess water after reachingequilibrium to the initial sample weight” [16,24]. A sample with high SC can be beneficialfor gastrointestinal motility and defecation and contribute to the prevention of constipation.Carrot pomace powders presented relatively low foaming capacities (<7%, Table 2) but withgood stability. FC and FS are due to the presence of proteins, which form an uninterruptedcohesive film around the air cells in the foam, reducing the surface tension at the air–waterinterface, therefore providing the foaming capacity [28]. Negi and Vaidya [29] also reportedlow FC for apple pomace powder (2%) while Grover et al. [30] obtained a value of 7% FC forunsieved apple pomace and 11.00% for particle size < 300 µm. The bulk densities of carrotpomace powders varied between 0.45 g/cm3 and 0.56 g/cm3 (Table 2) with these valuesbeing close to those reported by Michalska et al. [31] for blackcurrant pomace powders(0.45–0.42 g/cm3). Particle density is affected mostly by the solids content which is quitegreat in fruit by-products such as pomace [31].

The color of carrot pomace is mainly due to carotenes which are partly transformedinto vitamin A [8]. Alam et al. [3] reported values of 65.0 for L*, 8.6 for a*, and 20.6 forb* parameters for carrot pomace convective dried and without any pretreatment, whichwas close to the results of the present study (Table 3). The color of carrot roots dependson the variety and ranges from orange to purple, depending on the chemical compoundscontained [32]. For example, purple carrot color is mainly due to the presence of antho-cyanins, while orange color varieties is due to the presence of carotenoids [32]. Niagaracarrot pomace powder exhibited the highest color intensity which may be related to thebeta carotene content, a fact also supported by the FT-IR spectra which revealed the high-

Appl. Sci. 2022, 12, 7989 12 of 15

est intensity of the peak at 1736 cm−1 associated with this compound. Generally, foodcarotenoids are classified into carotenes and xanthophylls, which are responsible for thered or yellow color of the product [1].

The microstructures of carrot pomaces studied in this paper showed compact fibrousstructures. Sucheta et al. [19] reported the intact cellular structure of black carrots thatcould be related to the filled polymer network and also to the strong linkages of pectinmolecules with the pigments. Plant cell walls are formed of complex polysaccharide net-works with diverse structural and physiological importance, with pectins being the compo-nents that, together with other polysaccharides paste neighboring cells and strengthen themfirmly [33]. The main components of the carrot cell wall are represented by pectin (galac-turonans, rhamnogalacturonans, arabinans, galactans, and arabinogalactans-1), cellulose(β-4, D-glucan), lignin (trans-coniferyl alcohol, trans-sinapyl alcohol, and trans-p-coumarylalcohol), and hemicellulose (xylans, glucuronoxylans β-D-glucans, and xyloglucans) [1].

A comparison of FT-IR absorption bands between the results obtained in the presentstudy and those found in the literature are listed in Table 4. The peak at 1736 cm−1 due toC=O stretching can be led to the bonds present in β-carotene [34]. The peak at 1456 cm−1 isrelated to scissoring (CH2) bending, while the peaks found at 1421 cm−1 and 1367 cm−1

are assigned to (CH3) and (CH2) bending, respectively. [20]. The bands observed between1550–1650 cm−1 in FT-IR spectrum of carrot pomace (Figure 2b) are the indicators of theC=C stretches in the pectin fractions [21]. The presence of the -OH groups of water wasidentified between 3000 and 3600 cm−1 as a broad band. The peaks at 3324 cm−1 givenby the –OH stretching vibrations also led to the H-bonded hydroxyl of polysaccharides orpolyphenols [19]. The peaks at around 2898 and 1606 cm−1 can be associated with the –CHstretching vibrations and the appearance of free ionic non-esterified carboxyl (–COO)molecules of galacturonic acid [19]. The presence of cellulose in carrot pomace powderswas suggested by the absorption bands found at 1421, 1367, 1104, and 1032 cm−1 [22]. Thepeaks at 1649 and 1557 cm−1 given by the C–O, C–N, CNN (Amide I), and N–H, C–N(Amide II) [35] vibrations, respectively, can be related to the presence of proteins in thestudied samples. These results were in agreement with those obtained for the chemicalcomposition of carrot pomace powders which showed high content of fibers and importantamounts of proteins.

Table 4. Comparison of FT-IR absorption bands with previous results reported in theliterature [19,22,35].

MeasuredWavenumber

(cm−1)

Wavenumber fromthe Literature

(cm−1)Assignment Origin

3324 3000–3600 O–H and N–Hstretch C–H

Water, alcohols, phenols, carbohydrates,peroxides polysaccharides, lipids, and

carbohydrates

2898 2891 –CH stretchingvibrations Galacturonic acid

1717, 1736 1700–1799 C=O Lipids, beta carotene

1649 1600–1706Amide I of

proteins, C–O,C–N, CNN

Proteins

1606 1600–1630COO-

antisymmetricstretching

Polygalacturonic acid, carboxylate(pectin ester group)

1557 1460–1590Amide II of

proteins, N–H,C–N

Proteins

1421 1421–1428 CH3 symmetricbending Cellulose

1367 1370 CH2 bending Xyloglucan, Cellulose1329 1320–1330 Ring vibration Pectin1247 1243 C–O stretching Pectin

Appl. Sci. 2022, 12, 7989 13 of 15

Table 4. Cont.

MeasuredWavenumber

(cm−1)

Wavenumber fromthe Literature

(cm−1)Assignment Origin

1147 1147O–C–O

asymmetricstretching

Xyloglucan (glycosidic link)

1104 1103–1115 C–O stretching,C–C stretching Cellulose (C2-O2)

1032 1030 C–O stretching,C–C stretching Cellulose (C6-H2-O6)

The results obtained in the present study confirm the possibility of using carrot pomacein the production of value-added food, with low costs and with many benefits for consumerhealth. Some possible applications of carrot pomace powders would be wheat bread, gluten-free bread based on pseudo-cereals, fitness bars, biscuits, cakes, pasta, etc. Carrot pomacecould bring an important intake of nutrients, especially fibers, depending on the amountadded to the final product. The results regarding the functional properties of carrot pomaceflour are important for choosing the type of product and the dose that can be incorporatedin order to achieve the desired quality and maximum nutritional benefits, it being knownthat fiber-rich ingredients such as carrot pomace could impact dough or mass behavior,depending on the particle size and dose.

5. Conclusions

The chemical composition, functional properties, and molecular structures of carrotpomace powders investigated depended on the variety. The results obtained showed thatcarrot pomace is a rich source of fibers, carbohydrates, and minerals, which suggested itscapacity to improve the nutritional value of food products into which it can be incorporated.On the other hand, the functional properties in terms of water absorption and retentioncapacities, swelling capacity, bulk density, and foaming properties differed between carrotvarieties, with the Baltimore sample exhibiting the highest water absorption capacity, waterretention, foaming stability, and bulk density. The color also depended on the carrotvariety, the most luminous being the Baltimore sample, the most reddish, yellowish, andintense color being obtained for the Niagara variety. SEM micrographs revealed a compactstructure of carrot pomace powder, while FT-IR spectra revealed the presence of betacarotene, pectin, cellulose, proteins, and carbohydrates in the analyzed samples. Furtherresearch on the bioactive compounds quantification in carrot pomace would be necessaryto better highlight the benefits of using it to create novel, value-added products.

Author Contributions: Conceptualization, M.I.L., M.U.-I. and S.M.; methodology, M.I.L., M.U.-I.and S.M.; software, M.I.L., M.U.-I. and S.M.; validation, M.I.L., M.U.-I. and S.M.; formal analysis,M.I.L., M.U.-I. and S.M.; investigation, M.I.L., M.U.-I. and S.M.; resources, M.I.L., M.U.-I. and S.M.;data curation, M.I.L., M.U.-I. and S.M.; writing—original draft preparation, M.I.L., M.U.-I. andS.M.; writing—review and editing, M.I.L., M.U.-I. and S.M.; visualization, M.I.L., M.U.-I. and S.M.;supervision, M.I.L., M.U.-I. and S.M.; project administration, M.I.L., M.U.-I. and S.M.; fundingacquisition, S.M. All authors have read and agreed to the published version of the manuscript.

Funding: This work was funded by the Ministry of Research, Innovation and Digitalization within Pro-gram 1—Development of national research and development system, Subprogram 1.2—InstitutionalPerformance—RDI excellence funding projects, under contract no. 10PFE/2021.

Institutional Review Board Statement: Not applicable.

Informed Consent Statement: Not applicable.

Data Availability Statement: The data are available at the corresponding author at reasonable request.

Appl. Sci. 2022, 12, 7989 14 of 15

Acknowledgments: This work was supported by the Ministry of Research, Innovation and Digital-ization within Program 1—Development of national research and development system, Subprogram1.2—Institutional Performance—RDI excellence funding projects, under contract no. 10PFE/2021.

Conflicts of Interest: The authors declare no conflict of interest.

References1. Surbhi, S.; Verma, R.C.; Deepak, R.; Jain, H.K.; Yadav, K.K. A Review: Food, Chemical Composition and Utilization of Carrot

(Daucus carota L.) Pomace. Int. J. Chem. Stud. 2018, 6, 2921–2926.2. Heimendinger, J.; Chapelsky, D. Dietary Phytochemicals in Cancer Prevention and Treatment. In The National 5 a Day for Better

Health Program; Springer: Boston, MA, USA, 1996; pp. 199–206, ISBN 978-1-4613-0399-2.3. Alam, M.S.; Gupta, K.; Khaira, H.; Javed, M. Quality of dried carrot pomace powder as affected by pretreatments and methods of

drying. Agric. Eng. Int. CIGR J. 2013, 15, 236–243.4. Di Donato, P.; Finore, I.; Anzelmo, G.; Lama, L.; Nicolaus, B.; Poli, A. Biomass and biopolymer production using vegetable wastes

as cheap substrates for extremophiles. Chem. Eng. Trans. 2014, 38, 163–168. [CrossRef]5. Tanska, M.; Zadernowski, R.; Konopka, I. The quality of wheat bread supplemented with dried carrot pomace. Polish J. Nat. Sci.

2007, 22, 126–135. [CrossRef]6. Nawirska, A.; Kwasniewska, M. Dietary fibre fractions from fruit and vegetable processing waste. Food Chem. 2005, 91, 221–225.

[CrossRef]7. Schieber, A.; Stintzing, F.C.; Carle, R. By-products of plant food processing as a source of functional compounds—Recent

developments. Trends Food Sci. Technol. 2001, 12, 401–413. [CrossRef]8. Bao, B.; Chang, K.C. Carrot Pulp Chemical Composition, Color, and Water-holding Capacity as Affected by Blanching. J. Food Sci.

1994, 59, 1159–1161. [CrossRef]9. Singh, B.; Panesar, P.S.; Nanda, V. Utilization of Carrot Pomace for the Preparation of a Value Added Product. World J. Dairy Food

Sci. 2006, 1, 22–27.10. Kırbas, Z.; Kumcuoglu, S.; Tavman, S. Effects of apple, orange and carrot pomace powders on gluten-free batter rheology and

cake properties. J. Food Sci. Technol. 2019, 56, 914–926. [CrossRef]11. Lotfi Shirazi, S.; Koocheki, A.; Milani, E.; Mohebbi, M. Production of high fiber ready-to-eat expanded snack from barley flour

and carrot pomace using extrusion cooking technology. J. Food Sci. Technol. 2020, 57, 2169–2181. [CrossRef]12. Cot,ovanu, I.; Batariuc, A.; Mironeasa, S. Characterization of quinoa seeds milling fractions and their effect on the rheological

properties of wheat flour dough. Appl. Sci. 2020, 10, 7225. [CrossRef]13. Bordei, D.; Bahrim, G.; Pâslaru, V.; Gasparotti, C.; Elisei, A.; Banu, I.; Ionescu, L.; Codină, G. Quality Control in the Bakery

Industry-Analysis Methods. Galat, i Acad. 2007, 1, 203–212.14. Oladiran, D.A.; Emmambux, N.M. Nutritional and Functional Properties of Extruded Cassava-Soy Composite with Grape

Pomace. Starch 2018, 70, 1700298. [CrossRef]15. Elkhalifa, A.E.O.; Bernhardt, R. Combination Effect of Germination and Fermentation on Functional Properties of Sorghum Flour.

Curr. J. Appl. Sci. Technol. 2018, 30, 1–12. [CrossRef]16. Raghavendra, S.N.; Rastogi, N.K.; Raghavarao, K.S.M.S.; Tharanathan, R.N. Dietary fiber from coconut residue: Effects of

different treatments and particle size on the hydration properties. Eur. Food Res. Technol. 2004, 218, 563–567. [CrossRef]17. Okaka, J.C.; Potter, N.N. Functional and Storage Properties of Cowpea Powder-Wheat Flour Blends in Breadmaking. J. Food Sci.

1977, 42, 828–833. [CrossRef]18. Sucheta; Misra, N.N.; Yadav, S.K. Extraction of pectin from black carrot pomace using intermittent microwave, ultrasound and

conventional heating: Kinetics, characterization and process economics. Food Hydrocoll. 2020, 102, 105592. [CrossRef]19. Sucheta; Chaturvedi, K.; Yadav, S.K. Ultrasonication assisted salt-spices impregnation in black carrots to attain anthocyanins

stability, quality retention and antimicrobial efficacy on hot-air convective drying. Ultrason. Sonochem. 2019, 58, 104661. [CrossRef]20. Joda, B.A.; Abed Al-Kadhim, Z.M.; Ahmed, H.J.; Al-Khalaf, A.K.H. A Convenient Green Method to Synthesize β-Carotene from

Edible Carrot and Nanoparticle Formation. Karbala Int. J. Mod. Sci. 2022, 8, 20–27. [CrossRef]21. Jayesree, N.; Hang, P.K.; Priyangaa, A.; Krishnamurthy, N.P.; Ramanan, R.N.; Turki, M.S.A.; Charis, M.G.; Ooi, C.W. Valorisation of

carrot peel waste by water-induced hydrocolloidal complexation for extraction of carote and pectin. Chemosphere 2021, 272, 129919.[CrossRef]

22. Szymanska-Chargot, M.; Zdunek, A. Use of FT-IR Spectra and PCA to the Bulk Characterization of Cell Wall Residues of Fruitsand Vegetables along a Fraction Process. Food Biophys. 2013, 8, 29–42. [CrossRef] [PubMed]

23. Kumari, S.; Grewal, R.B. Nutritional evaluation and utilization of carrot pomace powder for preparation of high fiber biscuits.J. Food Sci. Technol. 2007, 44, 56–58.

24. Amin, S.; Jung, S.; Kang, I.; Duval, A. Valorization of Baby Carrot Processing Waste. J. Culin. Sci. Technol. 2021, 1–17. [CrossRef]25. Sharoba, A.; Farrag, M.; Abd El-Salam, A. Utilization of Some Fruits and Vegetables Wastes As a Source of Dietary Fibers in Cake

Making. J. Food Dairy Sci. 2013, 4, 433–453. [CrossRef]26. Damodaran, S.; Parkin, K.L.; Fennema, O.R. Fennema’s Food Chemistry; CRC Press: Boca Raton, FL, USA, 2007; ISBN 1420020528.

Appl. Sci. 2022, 12, 7989 15 of 15

27. Jaime, L.; Mollá, E.; Fernández, A.; Martín-Cabrejas, M.A.; López-Andréu, F.J.; Esteban, R.M. Structural carbohydrate differencesand potential source of dietary fiber of onion (Allium cepa L.) tissues. J. Agric. Food Chem. 2002, 50, 122–128. [CrossRef] [PubMed]

28. Ahmad, M.; Wani, T.A.; Wani, S.M.; Masoodi, F.A.; Gani, A. Incorporation of carrot pomace powder in wheat flour: Effect onflour, dough and cookie characteristics. J. Food Sci. Technol. 2016, 53, 3715–3724. [CrossRef] [PubMed]

29. Negi, T.; Vaidya, D. Functional Properties of Apple Pomace Powder. Int. J. Curr. Microbiol. Appl. Sci. 2019, 8, 589–595. [CrossRef]30. Grover, S.S.; Chauhan, G.S.; Masoodi, F.A. Effect of particle size on surface properties of apple pomace. Int. J. Food Prop. 2003,

6, 1–7. [CrossRef]31. Michalska, A.; Wojdyło, A.; Lech, K.; Łysiak, G.P.; Figiel, A. Effect of different drying techniques on physical properties, total

polyphenols and antioxidant capacity of blackcurrant pomace powders. LWT-Food Sci. Technol. 2017, 78, 114–121. [CrossRef]32. Witrowa-Rajchert, D.; Bawoł, A.; Czapski, J.; Kidon, M. Studies on Drying of Purple Carrot Roots. Dry. Technol. 2009, 27,

1325–1331. [CrossRef]33. Ando, Y.; Maeda, Y.; Mizutani, K.; Wakatsuki, N.; Hagiwara, S.; Nabetani, H. Impact of blanching and freeze-thaw pretreatment

on drying rate of carrot roots in relation to changes in cell membrane function and cell wall structure. LWT-Food Sci. Technol. 2016,71, 40–46. [CrossRef]

34. Kaur, P.; Ghoshal, G.; Jain, A. Bio-utilization of fruits and vegetables waste to produce β-carotene in solid-state fermentation:Characterization and antioxidant activity. Process Biochem. 2019, 76, 155–164. [CrossRef]

35. Thummajitsakul, S.; Samaikam, S.; Tacha, S.; Silprasit, K. Study on FTIR spectroscopy, total phenolic content, antioxidant activityand anti-amylase activity of extracts and different tea forms of Garcinia schomburgkiana leaves. LWT 2020, 134, 110005. [CrossRef]