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Selection of Lactic Acid Bacteria from Neeragaram, a South Indian fermented rice product, and evaluation of Swedish oats as a matrix for fermentation

Sivakumar, Pavithra LU (2020) KNLM01 20201
Food Technology and Nutrition (M.Sc.)
Abstract
Fermented foods are of great importance for their extended shelf life, nutritional value, safety, health benefits and additional sensory attributes. The Lactic Acid Bacteria plays a major role in most of the fermented foods. Thereby, an indigenous fermented rice product (Neeragaram) from southern part of India was studied along with the similarly fermented oats product. The products were earlier studied for the presence of LAB while the current study involves the identification of isolated and preserved LAB strains from the spontaneously fermented rice and oats. The genotypic technique, 16S rDNA sequencing, was employed for identifying the lactic acid bacterial species. The ten isolates were identified to be Weissella spp. The isolates... (More)
Fermented foods are of great importance for their extended shelf life, nutritional value, safety, health benefits and additional sensory attributes. The Lactic Acid Bacteria plays a major role in most of the fermented foods. Thereby, an indigenous fermented rice product (Neeragaram) from southern part of India was studied along with the similarly fermented oats product. The products were earlier studied for the presence of LAB while the current study involves the identification of isolated and preserved LAB strains from the spontaneously fermented rice and oats. The genotypic technique, 16S rDNA sequencing, was employed for identifying the lactic acid bacterial species. The ten isolates were identified to be Weissella spp. The isolates were further tested for their haemolytic activity and fermentation capability by assessing its biochemical response to selective sugar substrates. The isolates RE18 and OS21 were selected to primarily ferment the Indian based rice and Swedish rolled oats. The end products were evaluated for the LAB colonies when it was identified that the significant difference in the LAB colonies count resulted from the combined effect of difference in substrate and the strains employed. Also, the microbiological safety evaluation for the presence of Enterobacteriaceae was conducted which resulted in higher counts of approximately 4 log CFU/ml in oats samples while rice was comparatively safe. The metabolites were also quantified for the starter induced fermented samples and for the reference indigenous samples that were spontaneously fermented. The starter induced fermented samples possessed more SCFAs in comparison to the native samples. While the difference in substrate impacted the metabolites produced during fermentation.
Hypotheses: The bacteria isolated from the native fermented rice and oats sample is likely to possess probiotic properties, prebiotic producing capability, and fermentation capabilities.

Conclusions:
The isolates were recognized to be preliminarily safe if administered as probiotic, as they were non-haemolytic. Also, the fermentation capabilities of the strains existed but differed. Additionally, the identified species is renowned for the polysaccharide (prebiotic) production capability, but further studies are required to affirm the same in the isolated strains. The substrate difference impacted the LAB count in fermented samples. Besides, the SCFAs were produced by the selected strains as metabolites resulting from fermentation. Hence, the identified species is preliminarily safe and possess health improving potential as probiotic with regards to SCFAs production while more studies are essential to conclude as a potential probiotic. (Less)
Popular Abstract
Fermented foods have a long and renowned history across the globe. The fermentation of food was adapted as a process to preserve food and extend its shelf life. Thereby, food was made available during unforeseen circumstances. Also, wastage of food was prevented by adapting fermentation process. Such similarly developed and consumed food is Neeragaram, which is a water based sour rice. Rice being the staple food in the southern part of India, it retains its value and need till day. Hence, the excess cooked rice available in the South Indian household is generally left to soak in water overnight and consumed the next morning. It was widely spoken for its health benefits but there are least detailed studies on the same. Thereby, to... (More)
Fermented foods have a long and renowned history across the globe. The fermentation of food was adapted as a process to preserve food and extend its shelf life. Thereby, food was made available during unforeseen circumstances. Also, wastage of food was prevented by adapting fermentation process. Such similarly developed and consumed food is Neeragaram, which is a water based sour rice. Rice being the staple food in the southern part of India, it retains its value and need till day. Hence, the excess cooked rice available in the South Indian household is generally left to soak in water overnight and consumed the next morning. It was widely spoken for its health benefits but there are least detailed studies on the same. Thereby, to understand the value of the product scientifically and with the aim to contribute valuable inputs to the food industry from the traditional product, the project was initiated.
Bacteria grouped as Lactic Acid Bacteria are widely involved in the fermentation of food besides yeast. Therefore, the bacteria involved in the fermentation of neeragaram was the
matter of interest. Further, bacteria were isolated from the spontaneously fermented food, neeragaram, and similarly fermented oats, using microbiological techniques and further identified using its genetic material and characterized using its response to certain defined
chemical environment. Oats was included in the project in concern with the Swedish market and the sustainability views in Sweden. Further, identified isolated bacteria were selected based on their characteristic response to the exposed chemical environment. It was important to ensure the safety of the consumer on consumption of bacteria to be employed in the fermentation. Therefore, the bacteria were tested for their capability to destruct the red blood cells of human which is likely to affect the human health leading to anaemia. The isolates with no effect on red blood cells were considered for further studies. Also, the response of bacteria to the sugars on consuming the same and production of metabolites was studied. The bacterial isolates were employed in the fermentation of rice and oats and the resulting products were studied for the employed bacterial
load, safety with least unwanted bacterial growth and the metabolites produced by the bacteria.
The metabolites produced on consumption of the rice and oats as substrate by the bacteria, generally involves in increasing the acidity of the product thereby reducingthe activity of acid
intolerant harmful bacteria, impart health benefits to the consumers and improves the texture and flavour of product.
Though preliminary studies provide positive direction in utilising the bacterial isolates for developing fermented products, more studies in detail in required to employ the identified bacterial isolates as a probiotic (live bacterial strains which imparts health benefits similar to the bacteria naturally existing in the gut and more) or as a source of prebiotic (generally complex polysaccharides that are consumed by the gut bacteria in producing metabolites that aid in improving human health or maintaining the same) in food. The detailed examination on the safety of the isolates is to be performed along with the study on health benefits and characteristics of the metabolites produced by every bacterium isolated. The precision of the study could be improved by isolating more strains from the original spontaneously fermented product and conducting similar studies on the same. Besides, study on different substrates employing the isolated bacteria, is likely to pave path for the development of food product with health benefits. (Less)
Please use this url to cite or link to this publication:
author
Sivakumar, Pavithra LU
supervisor
organization
course
KNLM01 20201
year
type
H2 - Master's Degree (Two Years)
subject
keywords
applied nutrition, food chemistry, industriell näringslära, livsmedelskemi, Fermentation, Rice, Oats, Lactic Acid Bacteria, Genotypic identification, Biochemistry, Short Chain Fatty Acids
language
English
id
9018756
date added to LUP
2020-06-18 17:37:17
date last changed
2020-06-18 17:37:17
@misc{9018756,
  abstract     = {{Fermented foods are of great importance for their extended shelf life, nutritional value, safety, health benefits and additional sensory attributes. The Lactic Acid Bacteria plays a major role in most of the fermented foods. Thereby, an indigenous fermented rice product (Neeragaram) from southern part of India was studied along with the similarly fermented oats product. The products were earlier studied for the presence of LAB while the current study involves the identification of isolated and preserved LAB strains from the spontaneously fermented rice and oats. The genotypic technique, 16S rDNA sequencing, was employed for identifying the lactic acid bacterial species. The ten isolates were identified to be Weissella spp. The isolates were further tested for their haemolytic activity and fermentation capability by assessing its biochemical response to selective sugar substrates. The isolates RE18 and OS21 were selected to primarily ferment the Indian based rice and Swedish rolled oats. The end products were evaluated for the LAB colonies when it was identified that the significant difference in the LAB colonies count resulted from the combined effect of difference in substrate and the strains employed. Also, the microbiological safety evaluation for the presence of Enterobacteriaceae was conducted which resulted in higher counts of approximately 4 log CFU/ml in oats samples while rice was comparatively safe. The metabolites were also quantified for the starter induced fermented samples and for the reference indigenous samples that were spontaneously fermented. The starter induced fermented samples possessed more SCFAs in comparison to the native samples. While the difference in substrate impacted the metabolites produced during fermentation.
Hypotheses: The bacteria isolated from the native fermented rice and oats sample is likely to possess probiotic properties, prebiotic producing capability, and fermentation capabilities.

Conclusions: 
 The isolates were recognized to be preliminarily safe if administered as probiotic, as they were non-haemolytic. Also, the fermentation capabilities of the strains existed but differed. Additionally, the identified species is renowned for the polysaccharide (prebiotic) production capability, but further studies are required to affirm the same in the isolated strains. The substrate difference impacted the LAB count in fermented samples. Besides, the SCFAs were produced by the selected strains as metabolites resulting from fermentation. Hence, the identified species is preliminarily safe and possess health improving potential as probiotic with regards to SCFAs production while more studies are essential to conclude as a potential probiotic.}},
  author       = {{Sivakumar, Pavithra}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Selection of Lactic Acid Bacteria from Neeragaram, a South Indian fermented rice product, and evaluation of Swedish oats as a matrix for fermentation}},
  year         = {{2020}},
}