Antioxidative properties and Lactobacillus population in traditional Sri Lankan pickle during fermentation
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Date
2015
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Journal ISSN
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Publisher
Uva Wellassa University of Sri Lanka
Abstract
In recent years, probiotic products have become a primary choice for the consumers because of their
health attributes (Yen-Ping Tan, 2007). Pickle may be a suitable product of carrying probiotic
bacterial strains to the host. Pickling is a method of fermentation of vegetables to extend their shelf
life. That process consists with the basis of reducing the pH value due to conversion of sugar to acid
by lactic acid bacteria (LAB). LAB are greatly important for human health as they help balance human
intestinal flora, thereby boosting overall immunity (Amit et al., 2012). Antioxidant compounds in
fermented foods play an important role as a health protecting factor. Scientific evidence suggests that
antioxidants reduce the risk for chronic diseases including cancer and heart disease. There is no
reported study done on evaluating the nutritional properties of Sri Lankan vegetable pickles fermented
with coconut vinegar. The main objective of this study was to evaluate the population growth of
Lactobacillus, pH, total phenols and antioxidant activity during fermentation of Sinhala pickle.
Materials and Methods
Sample preparation, determination of pH and Lactobacillus population
The samples for the isolation of LAB included the fermented mixed vegetables which was prepared
by mixing thoroughly, cleaned and diced vegetables (carrot, red onion, raw papaya, green chili) in
coconut vinegar solution, and was allowed to ferment at ambient temperature (32 C±2). The microbial
spread plate method was used to isolation of LAB in the MRS media from the pickle sample. The pH
of the withdrawn aliquots at every 24h during the fermentation was monitored using a digital pH
meter (HI 2211, USA) at 32 C (Shori et al., 2011).
Determination of Antioxidant Activity and Total Phenolic Content
Antioxidant activity (AOA) was measured by DPPH radical scavenging activity method according to
the method developed by Adak et al. (2013) with little modifications. Total phenol content (TPC) was
measured by Folin-Ciocalteu method with some modifications (Kriengsak et al., 2006).
Results and Discussion
Population of Lactobacillus in pickle
Traditionally, the fermentation of Sinhala pickle is processed by the LAB. The results showed that
the bacteria population increased from an initial number of 8.0997 0.56 Log10 cfu/g after 24 hours
fermentation at 37 ⁰C. The maximum bacteria growth was observed after 48 hours fermentation which
had significant difference with other ratios of bacteria except 72 hours bacteria count. After three days
storage at 37 ⁰C, the bacteria population decreased but, no significant difference was observed among
other storage time. In contrast, the numbers of LAB were much reduced at the end of storage (Table
1).
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Keywords
Science and Technology, Technology, Food Science, Food Technology