Application of of Blue Lightht-t-Emitting Diodes tion o

for

lue LBloof B

or or Food

ue L

d d P

ghhtt mittingEmELige L

PPreservation

(Presentation at 2016 APIFSC, 13 Oct 2016)

Hyunun-un-Gyun Yuk, Ph.D.Hyununun Gyun Yuk, Ph.DGyGy

Food Science and Technology

.Ph.D.

y y Programme Science and Technology y PrograPr

Department of ChemistryDepartment of Chemistry

National University of Singaporetional University of Singapo

chmyukhg@nus.edu.sg

3

Lightht-t-Emitting Diode (LED)

§ A semiconductor light source

§ Able to produce specific wavelength

§ Many advantages of the use of LEDs

compared to conventional lighting

Ø Small mass and volume, easy

manipulation, wavelength specific,

reduced heat output, and long life

Light-Emitting Diodes

LED

Indicators and signs

Indoor and outdoor lighting

Lighting in electronic appliances

Therapeutic uses

AgricultureFood

Food

preservation

Improve nutritional

values

Application of LED technology

4

?

(http://www.pulsaderm.com/pulsaderm-led-blue)

Proposed antimicrobial mechanism of LED

5

Schematic illustration of photodynamic action

(Jablonski diagram)

(Gupta et al. 2013. Biotechnology Advances. 31:5 607-631)

6

(Sharma et al. 2009. Toxicol. Lett. 185:211-218)

7

Ø Light sensitive compounds

(photosensitizers)

Ø Absorb light at specific

wavelengths (400 – 420 nm)

Chemical structure of coproporphyrin I

(http://www.brenda-enzymes.info/Mol/Mol.php4?n=8775&compound=coproporphyrin&s_type=5&back=1&limit_start=0)

8

Cross sectional diagram of the LED illumination system

(Ghate et al. 2013. Int J Food Microbiol. 166:399-406)

Inactivation of the selected Gram-negative bacteria during the

illumination with 405 nm LED at 4°C (18 mW/cm2).

9

*

*

*

*

-2.5

-1.5

-0.5

0 1.5 3 4.5 6 7.5

Lo

g N

/N0

Exposure Time (h)

405 nm

Control

*

**

*

-2.5

-1.5

-0.5

0 1.5 3 4.5 6 7.5

Exposure Time (h)

-**

*

*

*

-2.5

-1.5

-0.5

0 1.5 3 4.5 6 7.5

Exposure Time (h)

E. coli O157:H7 S. sonnei S. Typhimurium

(1) (97) (194) (292) (389) (486)Dose (J/cm2)

Bacterial inactivation in PBS by LED illumination

(Kim et al. 2016. Food Control. 59:99-107)

Inactivation of the selected Gram-positive bacteria during the

illumination with 405 nm LED at 4°C.

10

*

*

*

-2.5

-1.5

-0.5

0 1.5 3 4.5 6 7.5

Exposure Time (h)

*

*

*

*

-2.5

-1.5

-0.5

0 1.5 3 4.5 6 7.5

Lo

g N

/N0

Exposure Time (h)

405 nmControl

*

*

*

-2.5

-1.5

-0.5

0 1.5 3 4.5 6 7.5

Exposure Time (h)

B. cereus L. monocytogenes S. aureus

(Kim et al. 2015. J Photochem Photobiol. 153:33-39)

Does 405 nm LED really work with real food matrix?

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Temperature profile

The surface temperature profile on fresh-cut papaya recorded during

405 nm LED illumination at set temperature of 20 °C

10

15

20

25

30

0 50 100 150 200 250 300Tem

pera

ture

(°C

)

Exposure time (min)

405 nm Incubator

12

(Kim et al. 2016. Food Microbiol. Accepted and in press)

S. Agona S. Newport

S. Saintpaul S. Typhimurium

Effect of of 405 nm LED D on n n Salmonella a on cut papaya

Inactivation of

Salmonella spp. on

the fresh-cut papaya

surface by 405 nm

LED at set

temperature of 4°C

(actual temp. 7.2°C). 13

(Kim et al. 2016. Food Microbiol. Accepted and in press)

Inactivation of

Salmonella spp. on

the fresh-cut papaya

surface by 405 nm

LED at set

temperature of 10°C

(actual temp. 13.2°C).

S. Agona S. Newport

S. Saintpaul S. Typhimurium

14

(Kim et al. 2016. Food Microbiol. Accepted and in press)

Inactivation of

Salmonella spp. on

the fresh-cut papaya

surface by 405 nm

LED at set

temperature of 20°C

(actual temp. 23.2°C).

S. Agona S. Newport

S. Saintpaul S. Typhimurium

15

(Kim et al. 2016. Food Microbiol. Accepted and in press)

Temperature

( C)

Time

(h) Sample

Color difference

(ΔE)

Firmness

(N)

10 0 Fresh 4.0 0.9a

36 Control 33.3 4.1a 1.7 0.1b

405 nm 36.9 8.9a 1.8 0.3b

4 0 Fresh 2.6 0.3a

48 Control 25.1 6.1a 1.2 0.4b

405 nm 30.8 8.2a 1.1 0.3b

Quality y changes of papaya during LED illumination

Color and texture changes in papaya by 405 nm LED illumination

Different letters within the same column at same storage temperature differ

significantly (n=6; P < 0.05).

16

(Kim et al. 2016. Food Microbiol. Accepted and in press)

( C)

Time

(h) Sample

Antioxidant capacity

(mg /100 g)

Flavonoids

(mg /100 g)

Ascorbic acid

(mg/100 g)

β-carotene

(mg/100 g)

Lycopene

(mg/100 g)

10 0 Fresh 39.08 5.97a 1.85 0.30a 16.85 2.77a 0.29 0.11a 0.34 0.22a

36 Control 36.95 4.75a 3.14 0.88b 17.20 1.22a 0.36 0.18a 0.64 0.09ab

405 nm 34.63 3.96a 3.36 0.53b 16.23 1.53a 0.30 0.13a 0.75 0.14b

4 0 Fresh 39.18 10.91a 1.85 0.30a 18.00 1.89a 0.29 0.11a 0.34 0.22a

48 Control 37.53 14.18a 1.85 0.08a 14.62 3.37ab 0.37 0.19a 0.52 0.11ab

405 nm 39.27 10.05a 2.84 0.59b 13.26 0.77b 0.38 0.15a 0.64 0.06b

Effect of 405 nm LED on antioxidant capacity and contents of ascorbic

acid, flavonoids, β-carotene, and lycopene in papaya

Different letters within the same column at same storage temperature differ significantly (n=6; P < 0.05).

Quality y changes of papaya during LED illumination

17

(Kim et al. 2016. Food Microbiol. Accepted and in press)

18

(Sharma et al. 2009. Toxicol. Lett. 185:211-218)

Antibacterial mechanism of 405 nm LED

19

**

0

1

2

3

4

SA ST

Lo

g r

ed

uc

tio

n (

CF

U/m

l)

(a)

Control 405 nm

0

2

4

6

8

SA ST

TB

AR

S(n

MM

DA

eq

uiv

ale

nts

/1

011

ce

lls

)

(b)

Control 405 nm

Log reduction (a) in S. Agona (SA) and S. Typhimurium (ST) and lipid

peroxidation (b) by 405±5 nm LED illumination at 4 °C for 7 h (a total

dose of 900 J/cm2) in phosphate buffered saline (PBS).

(Kim et al. 2016. Food Microbiol. Accepted and in press)

Epifluorescent micrographs of Live/Dead S. Typhimurium stained

with the BacLight nucleic acid stain.

20

(Kim et al. 2016. Food Control. 59:99-107)

§ 405 nm LED inactivated more than 90% of the population of all

six pathogens under the refrigeration condition.

§ Inactivation of Salmonella spp. on fresh-cut papaya was

observed during the illumination of 405 nm LED at chilling

conditions.

§ 405 nm LED could not significantly cause a negative effect on

fresh-cut fruit qualities.

21

Summary and conclusion

§ These findings confirmed genomic DNA oxidation and the loss of

membrane functions, preferentially in efflux pump and glucose

uptake activity due to LED illumination but only slight damages

to membrane potential and integrity.

§ This study suggests that a chiller equipped with 405 nm LEDs

could be used to preserve fresh-cut fruits at retail store without

deterioration, minimizing the risk of foodborne diseases.

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Summary and conclusion

§ This research was funded by the A*STAR grant (SERC 112-177-

0035) and MOE Tier 1 grant (R-143-000-624-112).

§ Kim Min-Jeong, Ph.D. student

§ Vinayak Ghate, Ph.D. student

§ Dr. Amit Kumar, Research Fellow

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§ This research was funded by

Acknowledgment

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