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UNIVERSITY OF NAIROBI.
INDUSTRIAL PROJECT REPORT.
EVALUATION OF THE EFFECT OF TOMATO POWDER ANDREDUCED NITRITE LEVELS ON KEEPING AND SENSORY
QUALITY OF FRANKFURTERS.
PROJECT RESEARCHED BY:
FANUEL. O. ODHIAMBO.
A24/0103/2009.
SUPERVIRSOR:
DR.CATHERINE .N. KUNYANGA.
SUBMITED IN PARTIAL FULFILMENT OF BSC. FOODSCIENCE AND TECHNOLOGY.
DEClARATION.
This is my original work in partial fulfillment of a degree in Bsc Food Science andTechnology and has never been presented in any academic institution.
Student :Opiyo Fanuel Odhiambo.
Sign:~ __
Approved by: Dr Catherine .N. Kunyanga
Sign:~
Date:
Date
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AKNOWLEDGEMENT.I wish mv sincere sratitude to mv suoervlsor DR. Catherine Kunvanaa for her close suoervisionand positive critisms, Chief Lab Technician Mr. Jeremiah M'ithika and Senior Lab Technician MsJacinta Muchiri for their technical assistance, not forgetting the pilot plant management whoprovided me with raw materials and technical assistance during the research period.
Lastly, Iwish to thank. the department of Food Science Nutrition and Technology who partly
provided finance for this research.
Hi
ABSTRACT.The main aim ofthis study was to evaluate the effect of a combination tomato powder andreduced nitrite on keeping and sensory quality of frankfurters. Nitrites which act aspreservative against C.botulinum and as an antioxidant is the main preservatives used to avoidundesirable effects during storage hence can't be completely substituted. There have beennumerous concerns on its use because of the possibility of the formation of carcinogenicnitrosamines in the food product. Frankfurters were formulated with tomato powder at 0010(T1), 1% (T2); 2% (T3), 3% (T4) and 4 %( T5) levels and reduced nitrites from 18g/kg, 16g/kg,14g/kg, 12g/kg and10g NPS per kg of meat respectively. According to the results, the additionof tomato powder did not have significant (p>O.05) effect on microbiological stability butrecorded a significant (p<O.05) decrease in the rate of lipid oxidation and in redness offrankfurters .The sample containing 4% Tomato powder and 12gNPS/kg meat was the optimalformulation. The scores of overall acceptability in samples containing tomato powder weresignificantly higher (p<O.05) than that of control sample (T1) within the 12 days of refrigeratedstorage (5° C). The frankfurters with tomato powder up to 4% were found to be wellacceptable. The optimal frankfurters formulation had increased storage stability, improvedtaste and better color with well documented health benefit due to the functional additiveLycopene in tomato powder.
Table of ContentsDECLARAnON........................................................................................................................................................... i
ACKNOWLEDGEMENT ii
ABSTRACf .iii
CHAPTERONE 4
1.0 INTRODUCTION 4
1.1 PROBLEMSTATEMENT 5
1.2 PROBLEMJUSTIFICATION 6
1.3 MAIN OBJECTIVE.............................................................................................................•.•........ 6
1.4 RESEARCHHyPOTHESiS 6
CHAPTER2 7
2.0 LITERATUREREVIEW 7
2.1 Tomatoes (Solanum Iycopersicum) 7
2.2 Antioxidant activity of carotenoids 7
2.3 Role of nitrites in frankfurters manufacture 7
CHAPTER3 8
3.0 MATERIALSAND METHODS 8
3.1 Materials 8
3.1.1 Preparation of tomato powder 8
3.1.2 Processing offrankfurters 8
3.2 RESEARCH DESiGN AND MHHODOlOG,( 9
CHAPTER4 11
4.0 Chemical and sensory analysis 11
4.1 Determination of lipid oxidation 11
4.2 Determination Lycopene content 11
4.4 Microbiological analysis 11
4.5 Sensory evaluation 12
4.6 Statistical analysis 12
5.0 RESULTS 13
2
3
CHAPTER 6 16
6.1 DISCUSSIONS 16
6.1.1 RANCIDITY ANALYSIS 16
6.1.2 MICROBIOLOGICAL ANALYSIS 17
6.1.3 LYCOPENE CONTENT 18
6.1.4 SENSORY ANALySiS 18
7.1 CONCLUSION 19
7.2 RECOMMENDATIONS 19
APPEN DIX 20
REFERENCES 22
CHAPTER ONE.
1.0 INTRODUCTIONMeat emulsion products contain meat and fat as the major ingredients which are verysusceptible to chemical and microbial deteriorations .The most prominent among chemicaldeteriorations is fat oxidation (Adeyemi, 2011).Lipid oxidation refers to oxidative breakdown ofpolyunsaturated fatty acids, which causes, off-odors and rancid taste or warmed over flavor
thus lowering quality of frankfurters {Gunnison, 1981).ln order to prevent lipid oxidation,natural or synthetic antioxidants are usually added.
The sources of microbial contamination during the processing of frankfurters include meatcomponents, seasonings, ingredients and poor hygienic practices in the slaughter house andprocessing plant such as sticking knives into meat and failure to store equipment hygienically.
This leads to microbial spoilage (Hansen, 2003).The microbial growth is prevented using
antimicrobials such as nitrites and nitrates.
The nitrites and nitrates are mainly added to the meat emulsions to; fix and develop pink color;Inhibit microorganisms (Clostridium botulinum); it act as an antioxidant and develop desirableflavors (Senjurk, 200S).Nitrites and nitrates are responsible for nitrite inducedmethaeglobinaemia due to oxidation of heme-iron to ferrous iron inhibiting its function as an
effective oxygen transporting proteins (Sally et al.,2001).This may cause difficulties in breathing,dizziness, headache and death. Nitrites also react with secondary and tertiary amines toproduce nitrosamines which are reported to be carcinogenic. Numerous studies have
confirmed nitrites contribution to various cancers such as, stomach, colorectal and pancreaticcancers (Ferguson, 2010).
Autoxidation is usually prevented by the use of synthetic phenolic antioxidants such as
Butylated hydroxylanisole (BHA), butylated hydroxytoluene(BHT} and ascorbic acid. However
there is evidence that these synthetic antioxidants have potential adverse health effects andexperimental gallate toxicity and studies on tetragenieity and mutagenicity are available{Heijdena et al., 1987).Both carcinogenic and anti-carcinogenic activities has been reported forBHA and BHT (Botterweck, 2000).Cancer of fore stomach in Syrian hamster (rodent) was
reported after they consumed large BHA quantities, hence the use of synthetic antioxidants isillegal in baby foods (Gunnison,1981).
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Therefore, there are increased safety concerns on chemical food additives hence the promotionof readily and naturally available materials and the use of appropriate preservation methods.Advertent use of natural antioxidants has received much attention, in this case tomato powder.
Adding tomato and tomato products or Lycopene to meat could lead to products with healthbenefits. A few studies have been reported regarding the use of tomato products or Lycopenein meat and meat products ( 0sterlie and Lerfall 2005; Deda et el., 2007). The present study wasdone for incorporation of different level of Lycopene-rich tomato powder as antioxidant andfunctional additive in frankfurters.
Tomatoes are fast becoming one of the favorite foods, as they are good source of antioxidantsand antimicrobials. Apart from reducing lipid oxidation in oil and fatty foods, tomatoes canward off various types of cancer, prevent brain degeneration and cataracts. Tomatoes containLycopene, a relatively rare member of the carotenoid family, and twice as powerful as 13-carotene (Adevemi et al.,2012).Studies have shown that men who eat more tomato or tomatoproducts have significantly lower rate of prostate cancer. The carotenoids and phenols such asfoliates and flavonoids present in the tomato extract powder have the ability to quench singletoxygen and attract peroxvl radicals, halting the chain reactions. Other studies show thatLycopene prevents colon, lung and breast cancer (burger, 1998). Tomatoes also containglutathione an antioxidant that boost immune function. Hence this study reveals theantioxidant and antimicrobial potential of tomato powder.
Tomato products lower the pH of the meat emulsions, thus lowering growth of microorganismsleading to increased storage stability (Olson, 1989).
1.1 PROBLEM STATEMENT.Potassium and sodium salts of nitrites are widely used in curing of meat emulsion products(Stevananoic and Sentjurc, 2005). However safety of nitrites and nitrates to human health hasbeen questioned (Choi et al., 2007).Nitrites reacts with secondary and tertiary amines to formcarcinogenic compounds called nitrosamines.
Numerous studies have confirmed nitrites contribution to various cancers including colorectal,stomach and pancreatic cancers (Fegurson, 2010).Thus demand for natural of organicprocessed meat and meat products such as sausages which are cancer free may lead to marketgrowth in meat and meat products industry {Sebranek and Bacus,2007}.
Therefore there is need to find aJternative naturaJ pJant materjaJ which provides alternative
color, antioxidant and antimicrobial activities since they are organic, non-carcinogenic and
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reliable hence can substitute or reduce the amount of nitrates and nitrites with minimal or noQualitycompromise with respect to sensory attributes and shelf-life.
Although there are alternatives for nitrites and nitrates in meat processing, they are hard to
replace completely due to their anti-botulinal effects (Viuda-Martos et al., 2009).Consumerspreference for naturally derived antioxidants ,antimicrobials and colorants is associated withtheir image of being healthy.
1.2 PROBLEM JUSTIFICATION.Proficiently reducing levels of nitrites and nitrates with natural tomato powder which causesminimal change in organoleptic property of frankfurters minimizes the use nitrates or nitriteswhich eventually reduces the risk of cancer associated with the above ingredients.
This is further justified by willingness of the consumer to pay significant premiums for organicfoods. Premiums of 200% or even more for organic meat and poultry products over
conventional products are common (Sebranek and Bacus, 2007).lt then follows that there isneed to reduce the amount of nitrites and substitute with natural antioxidant, in this casetomato powder. This is the principal essenceof this research.
1.3 MAIN OBJECTIVE.To evaluate the effect of a combination tomato powder and reduced nitrite on keeping andsensoryquality of frankfurters.
1.3.1 SPECIFIC OBJECTIVES.1. To evaluate the Lycopene content of the frankfurters.2. To determine the antioxidant and antimicrobial activity of lycopene of the tomato
powder.
3. To evaluate the optimal levels of tomato powder with high antioxidant activity.4. To evaluate the optimal levels of tomato powder with high antimicrobial activity.5. To determine acceptability of the optimal formulation of frankfurters.
1.4 RESEARCH HYPOTHESIS.The frankfurters treated with a combination of natural tomato powder and reduced nitrites
have the same or improved keeping and sensory quality as the frankfurters treated with nitritesonly.
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CHAPTER 2
2.0 LITERATUREREVIEW.
2.1 Tomatoes (Solanum Iycopersicum).An edible typically red vegetable produced in Kenya mainly in greenhouse making it availablethroughout the year at an affordable price(according to Kenya Horticulture DevelopmentProgramme).Tomatoes are an integral part of the human diet worldwide. Although they arefrequently consumed fresh, over 800.10of tomatoes are consumed as processed products such astomato juice, paste, pure, ketchup and sauce. Recent studies have indicated the potentialhealth benefits of a diet rich in tomatoes and tomato products (Tapiero et al., 2004). Tomatoand tomato products are the major sources of Iycopene and are considered to be importantcontributors of carotenoids in human diet (Tapiero et al. 2004; Goula). They are rich in Iycopeneand other carotenoids such as ~-carotene, phytoene, phytofluene and lutein (Choski and Joshi2007). The ability of Iycopene to act as a potent antioxidant is thought to be responsible forprotecting cells against oxidative damage and thereby decreasing the risk of chronic diseases(Omoni and Aluko, 2005).
Regular tomato and tomato products have been correlated with reduced risk of various types ofcancer (Laveli and Rizzolo. 2000).These positive attributes are due to antioxidants particularlycarotenoids (Lycopene), flavonoids, and beta carotene (Odribozola, 2008).
2.2 Antioxidant activity of carotenoids.The carotenoids and phenols such as foliates and flavonoids present in the tomato powderhave the ability to quench singlet oxygen and attract peroxyl radicals, halting the chainreactions.There are indications that antioxidant activity of tomato powder depend on Iycopeneand phenolic compound contents {Odwozola ,2008}.Lycopene is the carotenoid that impartsred color to tomatoes and water melons, and constitutes 80 to 90% of the total carotenoidsfollowed by ~- carotene. Its common in acyclic, cyclic and shortened form.Carotenoids havebeneficial biological activities and their use in feed is recommended due to their vitamin A andantioxidant activity(Delgado and Lopez,2003).Lycopene content increases with ripeness.
2.3 Role of nitrites in frankfurters manufacture.Nitrites and nitrates play an important role in play multipurpose role; in addition to effectivelyinhibit the botulism., it also functions in the development of typical cured meat color ,flavorand as an antioxidant{Rincon et al,2008).They are carcinogenic, studies show that consumptionof cured meat products increases the risk of colorectal cancer by 12-17%; this is associated with100g of meat(Ferguson,2010).Nitrites react with secondary and tertiary amine forming n-
8
nitrosamines which are carcinogenic to the body. Use of nitrates and nitrites in cured meatexperienced a serious draw back in the late 1960s in USA. Due to n-nitrosamine scare, hencethe need for their substitution with natural non-carcinogenic materials.
CHAPTER 3.
3.0 MATERIALS AND METHODS.
3.1 Materials.• Fresh pork was purchased from the Dagoretti slaughterhouse in Dagoretti market whiJe
fresh tomatoes (Cal jay) were purchased in kangemi market.• Chilled pork back fat,sorbic acid collagen casings, ice and Nitrite Pickling Salt and (6g
NaN02 + lkg NaCImixture) were purchased from the pilot plant.• Nutmeg, SlTP and starch were purchased from a local supermarket.
Allchemical reagents were purchased by the Department of Food Technology and Nutrition.
3.1.1 Preparation of tomato powder. (According to Nicholas, 2012 with slightmodifications).
The tomatoes were washed with dean water, then the ripe, un-bruised and good texturedtomatoes, free from any disease or microbial infection were selected, then cut into thin slices(approximately 2mm) then dried at 80°C for 2 hours followed by 60°C for 12 hours using a hot-air drying oven to the moisture level of 3-5%. The dried tomato was then ground using alaboratory blender. The obtained tomato powder will be kept in a clean plastic container.
3.1.2 Processing of frankfurters.The pre- chilled beef and pork was minced separately through 5mm disk using electricmincer.The lean meat was chopped in a bowl chopper and ~ ice ,tomato powder(except T1)
was added while ensuring that temperatures were less than 10°C. Starch, fat, STPP, sorbic acid,nutmeg and the remaining ice were added. Communition was continued until fine cut wasachieved. The obtained mass was filled into casings using manual filler, taking care not toincorporate air. The frankfurters were finally linked at 10 cm intervals, ensuring that they arefirm.They were arranged on the smoking bar, then cold smoked for 1 hour before steaming for10 minutes.The frankfurters were finally packed in 250 gauge polythene bags.
3.2 RESEARCH DESIGN AND METHODOLOGY.Five treatments of frankfurters sausages were made with similar amounts of in,eredients butvarying combination of tomato powder and nitrites (as Nitrite pickling salt). The first treatment
was taken as the control sample, it contained standard amount of nitrites (1.8%NPSbased onmeat mass) and no tomato powder. The amounts of tomato powder were varied (based onweight of sausage mass) while decreasing the amount of nitrite pickling salt in subsequenttreatments as shown below.
Treatments T5T1 T2 T3 T4NPS{g/kg meat mass} 18 14 1216 10Tomato powder(% sausage mass) o 1 2 3 4
3.2.1 Flow chart for the research design.Weighing of Ingredients
Mincing lean pork and pork
fat separately
Chopping lean meat while adding1/3 ice ass.
Idition of different treatments
ofNPSAddition of different treatments
of tomato powder
Addition of spices, pork fat and
the remaining ice while chopping
1Filling into casings
Hot smoke at 70C for 15 min
9
10
Analysis (sensory, microbiological and chemical)
Added other materials apart from the tomato powder and Nitrite pickling salt in each of thefrankfurters portions flkg of sausages per portion) as follows:
Materials Amountlean pork 55%Pork fat 25%Ice 20%Sodium Tripolyphosphate (STPP). 2.5/kg( lean beef +fat)Starch 30 gramsNutmeg 1 g/kg( lean beef +fat)Sorbic acid 2g/kg(lean beef +fat)
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CHAPTER 4.
4.0 Chemical and sensory analysis4.1 Determination of Lipid oxidation. (AOACmethod (2ooS} with slight modifications).
Was done in days; 4, 6, 8, 10and 12.By weighing 30 grams of sausage in dean crucibles.
The weighed sausages were dried in an oven at 8Q°C. for £ hours. Crushed the sample usingmortar and pestle. Then transferred into 250ml flat bottomed flask. 200ml petroleum ether(40-600Qwas added then agitated the contents using a Garber shaker for 30 minutes. Filteredthe extract using Whattman fitter paper number 41,then dituted the obtained extract with
petroleum ether (5 parts of light petroleum for each part of extract).The absorbance was thenread at 450nm on a spectrophotometer.
Calculated the percentage increaseabsorbance on dayThat is, relative absorbance =
in lipid oxidation, by taking day 4 as the base and12 as end storage absorbance.Absorbance on day 12 - absorbance on day 4
Absorbance on day 4
4.2 Determination Lycopene content according to Sharma and LeMaguer,1996 with slightmodifications).
Was carried out on days; 1limmediateJy after processjng), 8 and 12.
1 g of the sausage was weighed into 125 m\ f\ask wrapped with a\uminium foi\ .50m\ mixture ofpetroleum ether-acetone-ethanol (2:1:1) was added to the sample. Samples were shaken for 30minutes, 10ml distilled water added. The sample was left to separate into distinct, polar andnon-polar (containing Lycopene) layers. Obtained the standard curve of ~-carotene bymeasuring at 450nm standard solutions of petroleum ether containing 0.05 to 0.25 mg purecarotene per 100ml.Read the non polar extract at 450nm in a spectrophotometer then theconcentrations were read from ~-carotene standard curve and calculated in mg/100g
4.4 Microbiological analysis.Total counts of sausages stored at 3-50C were determined on days; 1{immediately afterprocessing), 4, 8 and 12.
Two duplicate 25 g samples were taken aseptically from each treatment, transferred to sterileglass container and homogenized for 2 minutes at room temperature with 225 ml sterile 0.85%(w/v) saline solution (NaCI) using laboratory shaker.10-2 and 10-3 dilutions of samples were
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3 - Represents dislike moderately. 7 - Represents like extremely.
prepared in 0.85% saline solution and plated in duplicates onto plate count agar (PCA) andincubated at 350 for 48 h under aerobic conditions for taking total bacterial count.
Counted the number of colonies with viable growth and recorded number of colony formingunits per gram (etu/g) sample. Recorded the microbial load after averaging the two readings.Calculated the change in microbial load.
4.5 Sensory evaluation of frankfurters on 7-point hedonic scale according to Warner,1980.
Was done immediately after preparation, at 10:00 am .Frankfurters from each batch was scaledin hot water until core temperature of 70°C is reached. Then put in oolvthene baa and cooled incold water.
The sausages were presented to taste panel of 10, then asked them to rate its sensory quality(ie.color, taste, overall acceptabllltv), on a hedonic scale of seven as follows:
1-Represents dislike extremely. 5 - Represents like moderately.
2 - Represents dislike very much. 6 - Represents like very much.
4 - Represents neither like nor dislike.
Clean water for rinsing the mouth after tasting each sample was provided to the taste panel.
4.6 Statistical analysis.The obtained data from sensory evaluation was analyzed by Analysis of Variance ( ANOVA)todetermine the significance of the samples at p<0.05 level
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CHAPTERS.
5.0 RESULTS
Table 1: Absorbance at 450nm reading frankfurters lipid oxidation secondaryproducts.Da T1 T2 T3 T4 T54 0.136 0.184 0.217 0.361 0.4316 0.452 0.406 0.382 0.404 0.5108 0.464 0.506 0.454 0.502 0.60110 0.588 0.523 0.525 0.513 0.61812 0.711 0.763 0.716 0.703 0.693%change In relative 310 184 142 70 43absorbance
The above readings are averages of two readings.
% change in Relative absorbance = Absorbance on day 12-absorbance on day 4 x 100Absorba nee on day 4
0.9
0.8
0.7
0.6Ec: DAY 40 0.5LI'l
DAY 6~.•...ro 0.4Q) DAY 8uc:ro
0.3 DA'{10.0•....0 DAY 1211<{ 0.2
0.1
0
T1 T2 T3 T4 T5
Fig 1: Absorbance at 450nm reading frankfurters lipid oxidation secondary products
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Table 2:Microbiological load offrankfurters stored at 50Cfor 12days period.Day Tl T2 T3 T4 T51 3.48 x 104 2.97x 104 4.48x 104 2.01x 104 4.05x 104
4 1.50x 104 1.75x 104 4.12x 104 1.57x 104 2.80x 104
8 1.39x 104 1.21x 104 2.11x 104 1.07x 104 2.01x 104
12 1.43x 104 1.95x 104 3.90x 104 1.27x 104 4.91x 104
Day8/day 1 0.4 0.41 0.47 0.53 0.49Day 12/day 1 0.41 0.66 0.87 0.63 1.21These readings are averages of two readings.
MICROBIAL LOAD IN FRANKFURTERS DURING 12 DAY STORAGE.
54.5
~ 4::J 3.5't
1"0 3.....t><-0 2.5ro.2 2
j~ 1.5..c0... 1.~~ 0.5
•• 1 4DAYS
8 12
T1
T2
T3
T4
T5
FigFlg 2 :microbial load In frankfurters during 12 day storage.
Table3:Lycopene content in mg/g of the frankfurters stored at SaCfor 12days period.Dav T1 T2 T3 T4 T51 0.00 0.63 0.95 1.39 1.988 - 0.46 0.62 0.97 1.3112 - 0.31 0.46 0.69 0.91
The above readings were done in duplicates the average values were obtained.T1was not further analyzed for lycopene content, It contained no tomato powder.The lycopene content was catcutated by lambert-beer equation (As4o·3Z.1/sampte wgt*10).
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2.5
2
b.O 1.500.-1 DAY 1-b.OE 1 DAYS-cQ) DAY 12•..c0u 0.5Q)cQ)C-ou 0>-....I
T2 T3 T4 T5Treatments
Fig3: Lycopene content in mgJ100g of the frankfurters stored at 50C for 12 days period.
Table 4: Average scores for sensory evaluation of frankfurters immediately afterprocessing.
Sensory attributesSampfe Cofor raste Overall acceptabilityT1 5.03 a 5.08 a 5.93 a
T2 5.73a 5.18 a 6.01 a
T3 5.92 a 5.15 a 6.07 a
T4 6.11 a 5.29a 6.03 a
T5 6.02" 5.27" 5.89"The sensory analysIs was done on a hedonic scale of 7.A score of 4 and above was acceptable.
Descriptive analysis was done in order to determine arithmetic means. Analysis of Variance(ANOVA)was performed with confidence interval of95
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CHAPTER 6
6.1 DISCUSSIONS
6.1.1 RANCIDITY ANALYSIS.Lipid oxidation is one of the main limiting factors Quality and acceptability of frankfurters.According to Morrissey et al. (1998) this is due to discoloration, off-flavor development and
production of toxic compounds. The percentage change in relative absorbance is indicative ofthe increase of secondary products of lipid oxidation during storage. % change in Relativeabsorbance increases during storage, Table 1 and fig 1 show difference in % change in relativeabsorbance between Tomato powder treated and non-tomato powder treated frankfurters.
The percentage change in relative absorbance in the sample T1 without Tomato powder wasexpected to be high throughout the storage period of frankfurters, since it had no extra
antioxidants from tomato powder such as Lycopene. Addition of TP at different levelssignificantly (p~O.OS)decreased oxidation in frankfurter samples during the 12 days of storageas compared to T1 (control sample}This is similar to results reported by Escalante etal.(2003}.Sample TS { 4%TP and 10gNPS/kg meat } had the lowest % change in relative
absorbance,48% as compared to sample T1(standard NPSonly} which had the highest % change
in relative absorbance of 310%.This is in agreement with results obtained by Deda etal.{2007.}This results show that addition of tomato powder significantly affected the rate of
production of secondary products of lipid oxidation mainly due to presence of Lycopene whichscavengesoeroxvl radicals forming stabilized carotenoids, Burton and Ingold,1984}.The additionof TP further provides small quantities of phenolic compounds such as flavonoids{Ostrlie.,et al
200S},which exert antioxidant activity by donating hydrogen atom. However the results showed
that TP had an anti-oxidative effects that were significant only within the 10 days of
refrigerated storage beyond which the anti-oxidative effects were insignificant{P>O.OS)betweenday 10 and 12 as depicted in table 1.This does not agree with observation Candogan (2002)
which indicates that antioxidant property of tomato paste becomes insignificant on day 8.This
could be due to high Lycopene concentration in tomato powder compared to tomatopaste,diference in tomato varieties as well as ripeness. Between day 10 and 12 the increase inabsorbance control sample Tl and other samples(containing varying levels of TP werecomparable. According to Osterlie and Lerfal,(200S)this could be due to decrease in anti-
oxidative components in Tomato powder such as Lycopene in. According to Eyiler, (2011) the
Lycopene could have also been converted in peroxyl radicals capable of acting as pro-oxidants,and undergoing pro-oxidation by themselves. Treatments T4 and TS had the lowest % change in
relative absorbance due to high TP levels as compared to control sample Tl,this indicates thatTPsignificantly reduces lipid oxidation(p<O.OS)during the first 10 days of refrigerated storage.
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6.1.2 MICROBIOLOGICAL ANALYSIS.The lowest microbial count of sample T4 on day1 compared to other samples was attributed tobactericidal effects of nitrites in combination with TP at 3% level. Sample T3 had the higherbactericidal effect than sample T1 (with standard NPS alone}.This could be attributed to theslow antimicrobial effects of nitrites due to its mechanism of action against microbes (Jay,1987).The highest microbial count was on sampleT3 which was comparable to TS.This may bedue to contamination of tomato powder during handling and processing, however there is nodefinite pattern on the difference in microbial load immediately after processing.
He increase in microbial load in sample TS after day 8 to 12 was rapid compared to the othersamples. This could be explained by the fact that Tomato powder and NPS levels were notsufficient to exhibit bactericidal effect and according to Viuda et al.(2009) the Nitritesconcentration reduced significantly during storage due reaction with active bio-compoundssuch as phenols and reaction with primary and secondary amines to form nitrosamines whichare carcinogenic.
The highest decrease in microbial load (by the 12th day) was observed in sample T1 (withstandard NPS with no TP),this was attributed to the potent Nitrites in the activeform(Jay,1987).However this is comparable to sample to T2 and T4.The increase in microbialload in sample TS(4%TP and 10gNPS/kg meat mass) after day 8 was very rapid compared tothat of the other samples which were relatively gradual. This could be due growth of lactic acidbacteria some of which are less susceptible to antimicrobial effects of Tomato powder (Eyler,2007).This explains the highest microbial load at the end of storage period in sample TS (4.90 x104 cfu/g) and the highest increase (1.2 times) during the 12 days of storage thoughinsignificant.
The observation on the viable count in sample T3 can be explained by the fact that some lacticacid bacteria were able to grow best at 4% TP as compared to 2% and 3%.
Lowest count on day 12 was observed in sampleT4(1.27 x 104 cfu/g);this was 0.63 times thecount on day 1 due to combined antimicrobial effects of Tomato powder and NPS.(Table 2).
This sample had the modest concentration NPS and thus a possible optimum of tomato powderor NPS concentration. Sample T1 with standard NPS had the highest decrease in microbial load-0.41 times, the day 1 count on the iz" day (Table 2) but the count was comparable to sampleT2 with l%TP and 16gNPS/kg meat mass (1.95 x 105 cfu/g) and sample T4 with 3%TP and12gNPS/kg meat mass (1.27 x 104 efu/g).As shown in Fig 2.
The increase in the microbial count observed in all the samples on day 8 could be attributed todeterioration of the meat proteins which encourages microbial growth.This is in agreementwith( Deda et al,.2007) There was no significant (p>O.OS}effect of the tomato powder on
17
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microbial growth, the change in microbial load in control sample (Tl) was comparable to theother samples containing tomato powder after 8 and 12 day as shown in table 2.AIIthe sampleshad an acceptable microbial load since all recorded below 1.0 x 105 cfu/g ,the minimumthreshold according to Codex Alimenterious Commision(CAC).
6.1.3 LYCOPENE CONTENT.Is the carotenoid responsible for the red color of tomatoes as well as antioxidant property.Onday l(immediately after processing)Lycopene content in frankfurters increased from 0.63-1.98mg/g in dry weight basis, with the increase in Tomato powder in theformulations(Table3) No Lycopene was detected in sample Tl(without TP),hence was notanalyzed further. The Lycopene levels declined all the samples during continuedrefrigerated storage(Table3J .This result is in agreement with results ofOsterIie and Lerfal(200S).According to Deda et al.(2007),these changes are attributed to oxidation reaction ofLycopene with free radicals and other compounds formed during frankfurtersmanufacture and storage. The decrease in Lycopene levels resulted into significant increasein antioxidant activity in frankfurters (p<O.OS) between day 10 and 12, this is in shown infig 3.
6.1.4 SENSORY ANALYSIS.Acceptability ratings of sensory attributes (color, taste and overall acceptability) werecompared between the samples. The samples containing tomato powder yield significanthigher scores than control sample Tl (without Tomato Powder) in terms of color attribute. Thisresult is in agreement with results of Eyiler and Oztan(2005) and Deda et al.{2007}.According toCandogan (2002), this color improving effect of tomato powder is attributed by the red colorand antioxidant effect of Lycopene present in tomato. Similar results have been reported byCalvo et al.(2008) for dry fermented sausage. Sample T4 scored highest in terms of color (6.11)but no significant effect was observed taste scores (p>O.OS).The panelists were not able toappreciate any change in taste of frankfurters after addition of tomato powder. Overallacceptability in all the treatments received comparable values in response to control sample Tland samples containing TP.Hence increase in color intensity did not influence the overallacceptance significantly (p>0.05).Average results however showed that T4 was the mostacceptable in terms of taste and color while T4 was the most acceptable in terms of colorperception. (Table 4).
Allthe frankfurters samples were acceptable since all the recorded scores were above 4
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CHAPTER 7
7.1 CONCLUSION.Tomato powder and reduced nitrite combination improved both keeping and sensory quality offrankfurters. Samplescontaining tomato powder showed improved anti-oxidation stability and
improved color during storage(Table 1 and 4 respectively) ) therefore, the addition of tomatopowder improves the shelf life of frankfurters by significantly reducing the rate of lipidoxidation associated with storage. Addition of Tomato powder improved sensory propertieswithout significantly affecting sensory attributes of color, taste and overall acceptance.
The addition of tomato powder did not exhibit a significant effect on microbiological stability
(Table 2) during storage. This indicates that Lycopene present in tomato powder act both aspigment and good antioxidant in frankfurters but not as an anti-microbial. Hence tomato
powder added to frankfurters can partially make up for the use of nitrite and act as source ofnatural color while preventing lipid oxidation.
7.2 RECOMMENDATIONS.Study should be carried out to evaluate residual nitrite levels on the frankfurterformulations during storage.
Study should be carried out to determine the effect of sorbic acid and reduced nitrite levelson the growth of Clostridium botulinum.
More study should be done on possibility of using natural extracts to increase anti-oxidationstability of frankfurters during storage.
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APPENDIX
Table 5:ANOVA table for hedonic test for color.Source of variation df SS MS Calculated F- Table value
value (p<0.051Treatment 4.00 6.75 2.28 2.96 2.73Panelist 9.00 13.00 1.44 1.53 3.14Error 36.00 33.87 0.94Total 49.00 53.62For color, the calculated F value for the treatments of 2.96 was greater than the table value of2.73, the calculated F-value for the panelists of 1.53 was less than Table value of 3.14.Hencethere was a significant (p<O.OS) difference among the mean hedonic scores for the fivetreatments in terms of color but there was no significant panelist effect.
Table 6:ANOVA table hedonic scale for tasteSource ofvariation df ss MS Calculated F- Table value
value (p<0.05)Treatment 4.00 6.30 1.58 1.06 2.73Panelist 9.00 13.40 1.49 1.60 3.14Error 36.00 33.33 0.93Total 49.00 53.00
For taste, the calculated Fvalue for the treatments of 1.06 was less than the table value of 2.73,the calculated F-value for the panelists of 1.60 was also less than Table value of 3.14.Hencethere was no significant (p>O.OS) difference among the mean hedonic scores for the fivetreatments in terms oftaste and there was no significant pane list effect.
Table 7:ANOVA table hedonic scale for overall acceptability.
Source of variation df SS MS Calculated F- Table valuevalue (p<0.05
Treatment 4.00 5.42 1.36 1.68 2.73Panelist 9.00 3.61 0.40 0.49 3.14Error 36.00 29.10 0.81Total 49.00 38.14
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For overall acceptability, the calculated F value for the treatments of 1.68 was less than thetable value of 2.73, the calculated F-value for the panelists of 0.49 was also less than Tablevalue of 3.14.Hence there was no significant (p>O.OS) difference among the mean hedonicscores for the five treatments in terms of taste and there was no significant pane list effect also.
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REFERENCES.Adeyemi,. K.D. 2011: Effect of tomato powder on oxidative rancidity of broiler meat. AJFANO,Issue 12,VoI12.Pg25-28.
Allen,J.C and Hammilton,R.J. 1989: Rancidity in foods, Elsevier science publishers. EssexEngland.
Bduokas, J.G. 1999: Effect of natural colorant and nitrite on color attributes offrankfurters.Meat Science,S, 257-265.
Burton G.W and Ingold, K. 1984: ~-carotene :an unusual type of lipid antioxidant.MeatScience, 224, 569-573.
CaJvo, M.2007:Dry fermented sausages enriched with tomato peel.
Choski, S.2007: Areview article on Supercrttical Fluid extraction of Lycopene from tomatoand tomato products.Karaelmas Science and Engineering Journal.Vol. 26, Issue12.Pg 45-49.
Deda, M.2007: Effect of tomato paste and nitrite levels on quality characteristics offrankfurters (Meat Sci journal; Issue 46 pg 501-508).
EyJier Y.2007: Production of frankfurters with tomato powder and reduced nitrite levels.
Gunnison, S. 2004: Evaluation of effect of natural antioxidants on lipid oxidation of meatemulsions.Experimental biology and Medicine,Vol 218.pg140-143.
Hudson, B.). 1990: Food antioxidant, Elsevier science publishers. Essex England.
Jay J,M.l996: Modern food microbiology. New York: Chapman & Hall.
Le Maguer ,M.2000:Lycopene in tomatoes:physic-chemical properties affected by foodprocessing.Critical Reviews in Food Science and Nutrition. 40.1-42
Martos,M and Sendra,E .2009 :Cjtrus co-products as technological strategy to reduce
residual nitrite content in meat products. Food science Journal, Issue 23. Vol. 33 pg 88-91.
Nicholas ,O.2012:Production of Zinc fortified Tomato powder based on pumpkin seeds.
Odriozola, 1.2008: Antioxidant properties and shelf life extension of fresh cut tomatoesstored at different temperatures.lournalof Food and Agriculture. Vol. 88. Issue lfi.Pg 109.
Official method of analysis. ;2005 23rd edition. Washington DC: Association of OfficialAnalytical Chemists.
Olson, J. A.1989:Biological actions of carotenoids.Journal of Nutrition,119,94-95.
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Osterlie, M and Lerfal,J .2004 :Effect of Tomato product on storage quality and color ofminced meat. International food technology journal. Issue 33.VoI11.Pg134-142.
Sahee,K .2005:sodium nitrite and sorbic acid effect on Cbotulinum spore germination
Sebranek,G and Bacus,l.2007: Curing of meat products without direct addition of nitrites.America Association of Meat Science. Iowa State University.
Sempiri, J. 2012: Effect of natural colorants in meat. undergraduate project MakerereUniversity.
Viuda, M.2009: Evaluation of residual nitrite levels in cured meat patties. Meat Sci journal;Issue 72 pg 26-31.
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