Production and Characterization of Exopolysaccharide extracted from bacteria isolated in homemade and packed Idli batter

Diverse exopolysaccharide (EPS)-producing isolates were isolated from an Indian acidic fermented food (Idli) based on the colony morphology. Lactic acid bacteria are non-pathogenic organism widely distributed in nature typically involved in a large number of spontaneous food fermentation. One of the EPS-producing micro flora was selected for further characterization using FT-IR, SEM, TGA and XRD analysis. The effect of pH, salt and temperature on the yellow pigment were studied and these parameters are gently influence the growth of bacterial isolates. In pH the maximum yield of biomass were obtained at pH (8) . In temperature maximum yield at 40 C and in salt concentration (Nacl) the maximum yield were obtained with 2%. Effect of total phenolic content, antioxidant activity and reducing power assay influence the growth biomass of the bacteria. In the structural characterization, the FT-IR spectroscopy revealed the α-d-glucose nature of the EPS. The SEM showed smooth surfaces and compact structure. TGA results showed higher degradation temperature of 272.01̊ C. XRD analysis proved the 33.4% crystalline nature of the EPS. All the above characteristics of the EPS produced by L. lactis showed that the EPS is of a good-quality polysaccharide with potential applications in the food industry.

Enumeration of Microflora from Ingredients and Idli Batter

Background: Microorganisms are responsible for characteristic changes in the fermented foods. They result in the sequential changes during fermentation of food, resulting in souring, leavening and changes in flavour, body and texture. The present study was aimed to enumerate the natural microflora present in raw ingredients used as well in fresh and fermented idli batter. Methods: Study was conducted during the period 2019-2020 to develop solid state fermented cultures for whey based idli batter at Department of Dairy Microbiology, Dairy Science College, Bangalore. The raw ingredients used for idli preparation were sourced from local market of Bangalore. Lactic counts such as leuconostoc, enterococci, pediococci and lactobacilli, as well as yeast counts were enumerated using different selective media by pour plate method. Result: The leuconostoc count of rice rava, black gram dhal and fresh idli batter on sucrose agar ranged from 2.0 to 3.78 log10 cfu/g; Lactobacilli count on MRS agar varied from 2.0 to 4.11 log10 cfu/g. Yeast count on potato dextrose agar ranged from 1.6 to 2.3 log10 cfu/g. Lactic counts (includes leuconostoc, lactobacillus, pediococci, enterococci) in fresh idli batter ranged from 3.63 log10 cfu/g to 4.77 log10 cfu/g, whereas in fermented idli batter varied from 2.56 log10 cfu/g to 8.74 log10 cfu/g. The yeast counts in fermented batter ranged from 9.23 to 9.56 log10 cfu/g.

Isolation of Lactic Acid Bacteria from Idli Batter and Screening of Characters as Potential Starter Cultures for Development of Functional Food Using Bacopa monnieri

Functional foods are whole, fortified, enriched, or enhanced foods that provide health benefits to humans regularly. Numerous plant foods or physiologically active ingredients derived from plants have been investigated for their role in disease prevention and health. Natural lactic acid fermentation of Idli batter by lactic acid bacteria and yeast makes Indian breakfast as a potential source of probiotic microorganisms. Briefly, the organism was isolated; the predominant isolate was considered on the basis of colony morphology, staining techniques, and biochemical tests. Growth conditions of the organism, such as pH, salt tolerance, bile salt tolerance, heat sensitivity, were studied. Bacopa monnieri (Brahmi juice) was extracted and fermented with predominant isolate as a starter culture. Organoleptic, antioxidant, and antibacterial properties of the fermented product were evaluated. On staining, the predominant isolate was identified as Gram-positive non-spore-forming, non-motile rod shape bacteria. The phenotypic characteristics were further resolved on the basis of growth patterns in pH, salt, bile salt, and heat sensitivity. In conclusion, the study of biological efficacies of fermented extracts of Bacopa monnieri reveals the potent activities in the field of science.

Effect of PP Nanocomposite Multi-layered Film on Physicochemical Properties of Ready-To-Cook (RTC) Idli Batter and Prepared Idli Cake

Aim: The current study focuses on the effect of PP nanocomposite multi-layered film on physicochemical properties of stored idli batter and prepared idli cakes. Place and Duration of Study: Department of Food Packaging and System Development at Indian Institute of Food Processing Technology, Thanjavur, Tamil Nadu, India, between Aug 2018 and Dec 2019. Methodology: The developed PP nanocomposite multi-layered film composed with depositing silicon dioxide (SiO2) on polypropylene (PP) film (0.010 mm) and attached with ethylene-vinyl alcohol (EVOH 32%) film (0.066 mm). The Physico-chemical properties of developed multi-layered and commercial PP film stored idli batter with different blend ratios of rice to black gram (3:1 and 4:1) were evaluated in terms of pH, percent titrable acidity (% TA), colour value (∆E), viscosity (cP) and volume measurement (ml). Idli cake prepared with batter stored in multi-layered film and evaluated in terms of colour, texture and percent pore characteristics. The percent pore presents in per square inches of prepared idli cake with different blend ratios and fermentation time were analysed using the grayscale image in MATLAB. Results and Discussion: The pH value of stored batter ranges from 6.7 to 4.5 or lower, to reach pH below 4.5 or lower commercially stored batter took 24 h and batter stored in the multi-layered film took 36 h at ambient temperature. The multi-layered stored batter showed better results of physicochemical properties in terms of fermentation time. Idli cake prepared with 3:1 blend ratio showed good results in terms of textural properties with compared to 4:1 blend ratio. Idli cake prepared with 3:1 blend ratio showed more pore percentage (21.88-36.80%) as compared to 4:1 blend ratio (18-32.98%) in per square inch. Due to higher barrier properties of the multi-layered film, the bacterial count increases at a slow rate and help to extend the shelf life of packaged batter more than 30 h at ambient temperature.

Development of High Oxygen Barrier Multi-layered Packaging Film for Shelf Life Extension of Ready-to-Cook (RTC) Idli Batter

Aim: The current study focuses on development of high oxygen barrier multi-layered packaging film for shelf life extension of Ready-to-Cook (RTC) idli batter. Place and Duration of Study: Department of Food Packaging and System Development at Indian Institute of Food Processing Technology, Thanjavur, Tamil Nadu, India, between Aug 2018 and Dec 2019. Methodology: The developed multi-layered film composed with polypropylene (PP) nanocomposite by depositing silicon dioxide (SiO2) on PP (0.010 mm) film and attached with different thickness of barrier layers were PP (0.010–0.053 mm) and ethylene-vinyl alcohol (EVOH 32%) film (0.066 mm) using layer-by-layer (LbL) process. The physical and chemical characteristics of commercial (A) and all developed multi-layered (B, C, D, E and F) films were tested for barrier and mechanical properties. Results and Discussion: The SEM analysis confirmed that the developed PP nanocomposite multi-layered films have a presence of SiO2 with quasi-spherical structure with diameter ranging from 200 to 500 nm. FTIR analysis also identified the presence of Si-O-Si group on all the developed PP nanocomposite films at wavenumber ranges from 1100-900 cm-1 and 467 cm-1. The film composed with PP++SiO2+EVOH (sample F) showed lower in oxygen transmission rate (OTR) of 452.46±33.94 cc/m2/24h and water vapour transmission rate (WVTR) of 1.07±0.16 g/m2 day. The batter stored in sample F film help to extend the shelf life upto 33 h at ambient temperature and commercially stored batter spoiled quickly (24 h) at ambient temperature.