Effect of Benzoic acid and KMS on Shelf of Sinki (fermented radish) Bimala Shrestha, Ganga Prasad Kharel, PhD, Sushil Dhital

Institute of Science and TechnologyTribhuvan University, Nepal

Introduction Fermentation- One of the oldest forms of food preservation Sinki is a traditional Nepalese non-salted fermented food. Sinki – prepared only from radish and produced by a strict anaerobic lactic acid fermentation of radish tap roots (Karki, 1983) Sinki as being a product of Nepal defers significantly from Japanese blanched sunki Leuconostoc mesenteroides, Lactobacillus brevis and Lactobacillus plantarum are the major dominant lactic acid bacteria involving in fermentation of Sinki Leuconostoc mesenteroides and Lactobacillus plantarum are the initiator and the terminator of Sinki fermentation respectively (Sharma, 1992)

Objectives To prepare fermented radish (sinki) and compare its shelf life using Sodium benzoate and potassium metabisulphite (KMS)

Materials and Methods Freshly harvested radishes, washed, sun dried at DB= 33°C, WB= 24.87°C, RH= 97%. Dried sample had pH= 6.7, acidity=0.2%, MC= 64.5%. Dried sample salted with 0.75%, 1.5% and 2.5% (NaCl) and fermented for 10 days. Using1.5% NaCl – found to be optimum for fermentation based on sensory data (data not shown)

Resulted in pH= 3.64, acidity=2.52 and MC= 21.5%, one as control, and two samples placed in sodium benzoate and KMS

Fig 1. Effect of control and preservatives on the Sensory scores of sinki at 115 days storage.

Fig 2. Comparing days of storage for sensory evaluation

*Where 1 = dislike extremely and 9 = like extremely; n = 45

*Where 1 = dislike extremely and 9 = like extremely; n = 45

Texture Color Sourness Odor1

3

5

7

9 Blank KMS Na-benzoate

Mea

n S

enso

ry V

alue

*

Results

Texture Color Sourness Odor1

3

5

7M

ean

Sens

ory

Valu

e*

0d 15d 45d 75d 115d 145d1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

blank KMS Na-benzoate

Storage duration (days)

Mea

n sc

ore

Fig 3: Effect of preservatives and storage duration(days) on pH of fresh Sinki.

0d 15d 45d 75d 115d 145d1

1.5

2

2.5

3

3.5

4blank KMS Na-benzoate

Storage duration(days)

% A

cidi

ty

Fig 4: Effect of preservatives and storage duration(days) on acidity of fresh Sinki.

Discussion Fig.1 shows highest score in terms of color, taste, odor when stored at 115days while slightly lower score in terms of texture in comparison to storage days at 145 days In Fig.2, Na- benzoate showed best result up to 75 days than KMS. The acceptability of s Na-benzoate than KMS is due to its wide use as an antimicrobial agent as its acid is most active against yeasts and bacteria, and least active against moulds In Fig. 3, storing up to 145 days showed that blank had highest storage period, then Na-benzoate followed by KMS In Fig. 4, blank consistently declined indicating the least acidity while medium acidity about 2% developed by Na- benzoate may be due to least activity of it against moulds which destroys acid to some extent.

Conclusion Radish (sinki) at 1.5% salt well preserved at 135 days by sodium benzoate showed much acceptability. As the quality of the final product is judged on the basis of acidic taste and typical sinki flavor, hence we got the final product with acidity 2.5% and pH 4

AOAC (1990). “Official Methods of Analysis.” Association of Official Analytical Chemists, Washington DC. Karki, T.B, Iloh H., Nikkuni, S., Ohono M. (1983). Microorganisms associated with various pickles. Kharel, G.P and Hashinaga, F. (2004). Principles of food preservation. Printed by Shibundo Co. Ltd., Kagoshima, Japan. Pp. 178-198. Ranganna, S.(2003). Manual of analysis of fruits and vegetables products, Tata Mc Graw-Hill Publishing company ltd., New Delhi. Pp. Sharma L. (1992), Food Technologist, Ministry of forest and soil conservation, Babar Mahal, Kathmandu.

References

Pic. 1: Control Sample and Sample with preservatives