Loading...
Kerala Veterinary and Animal Sciences University, Wayanad
Browse
6 results
Search Results
ThesisItem Open Access STUDY ON POST FERMENTATION ACIDIFICATION BY DAHI STARTER CULTURES(VERGHESE KURIEN INSTITUTE OF DAIRY AND FOOD TECHNOLOGY MANNUTHY, THRISSUR, KERALA VETERINARY AND ANIMAL SCIENCES UNIVERSITY, 2023-01-03) SILPA K RAJ; DR. Ligimol JamesOne of the main constraints being raised about dahi, a traditional Indian fermented dairy product prepared at households and industrial level is the increase in acidity that occurs during its storage even after ensuring proper cold chain maintenance. This continued development of acidity after the desired fermentation is referred to as post-fermentation acidification (PFA), which is not at all desirable. In the current study, twenty-two dahi cultures were screened for their post acidification potential and only three, namely L. acidophilus 307, L. casei and L. helveticus 53, were found to be low post acidifying i.e., elicited ΔpH48 of ≤0.3 units on extended storage for 48 h at fermentation temperature. Activity profiling of the three low post acidifying cultures and two high post acidifying cultures, namely L. casei 01 and L. rhamnosus 18 during refrigerated storage could distinctly classify the cultures into two different acidification pattern categories agreeing with the results of the post fermentation screening procedure adopted. Effect of thermization at 65oC as well as of microwave treatment at 600W for different periods on post acidification of dahi samples prepared using L. rhamnosus 18 or L. casei 01 upon refrigerated storage was assessed. Regardless of the treatments and the starter culture used, significant (p < 0.01) decrease in pH and increase (p < 0.01) in titratable acidity and lactobacilli count were observed in all of the dahi samples. In general, thermization at 65°C for 30 sec, 60 sec, 2 min and 5min had no inhibitory effect on post-fermentation acidification. However, microwave treatment was found to control PFA during refrigeration though in a culture specific manner. The microwave treatments adopted were found to be effective in controlling PFA during refrigerated storage. The study also explored the possibilities of using UV and mild heat stress exposures to develop low post acidifying cultures. Adopted UV treatments resulted in significant(p<0.01) reduction of ΔpH48 of both the UV treated high post acidifying cultures but could not generate low post acidifying cultures. On the other hand, mild heat stress (460C for 1 h) exposure did not elicit any noticeable impact on the postfermentation acidification potential of both the culture. Current study could establish strain wise differences in the post fermentation acidification pattern ofdahi cultures and scientifically assess the impact of different treatments on post fermentation acidification. Outcome of this study calls for further studies to understand the genetic and enzymatic background of the differential post acidification pattern exhibited by the tested isolates.ThesisItem Open Access BIOPRESERVATIVE POTENTIAL OF LACTIC ACID BACTERIAL METABOLITES ON PANEER(COLLEGE OF DAIRY SCIENCE AND TECHNOLOGY MANNUTHY, THRISSUR, 2021-12-03) FARZANA BEEGUM M A; Ligimol JamesPaneer, also called Indian cheese is a nutritious traditional dairy product. A well-identified constraint in its marketing is its short keeping quality. Considering the present consumer demand for naturally preserved foods, biopreservation could be an appropriate option to address this limitation. Lactic acid bacteria (LAB) and their metabolites are well recognized as potential biopresevative agents. In this study the biopreservative potential of LAB metabolites for biopreservation of paneer was assessed. LAB were isolated from three different sources; orange, tomato and curd. The three isolates obtained were subjected to phenotypic and genotypic identification techniques and all were identified as Lactobacillus fermentum. Their partial 16S rRNA sequences were deposited in NCBI with accession No MH782089, MK 743954 and MK743952. On assessing the antimicrobial activity of all the isolates against indicator organisms Staphylococcus aureus and Escherichia coli by well diffusion assay, the isolate from orange was found to exhibit maximum antimicrobial activity and was selected for further studies. Treatment of MRS broth- culture free supernatant (MRS broth – CFS) with the enzymes proteinase K, catalase and neutralisation revealed organic acids as major contributors towards its antimicrobial activity. As an attempt towards using more economic and food grade growth media for the production of antimicrobial metabolite, suitability of paneer whey was assessed. Though paneer whey supplemented (mPW) with 3% sucrose and 0.3% buffering agent served as better option than normal paneer whey it was not effective as that of MRS broth. So further studies were carried out using MRS broth as the growth medium. Cultivation of the isolate in MRS broth at 37℃ for a period of 72 hr was found to be the optimised condition for the production of antimicrobial metabolite. Dipping paneer in broth CFS for a period of 30 min was selected as the mode of application, as this combination elicited better result than other combinations tested. On performing the shelf life studies for a period of 12 days under refrigeration, treated paneer samples exhibited a significantly better microbial and chemical quality than the control samples. Based on the result it could be concluded that the antimicrobial metabolites of the isolate Lactobacillus fermentum MH782089 could be a potential candidate for biopreservation of paneer. The shelf life of paneer under refrigerated condition could be extended up to 12 days.ThesisItem Open Access CHARACTERIZATION OF PSYCHROTROPHS SURVIVING PASTEURIZATION(COLLEGE OF DAIRY SCIENCE AND TECHNOLOGY MANNUTHY, THRISSUR, 2022-08-18) VISHNU SURESH; LIGIMOL JAMESPasteurization is the major thermal preservation process the dairy industry adopts to address the safety hazards associated with milk and milk products. Microorganisms capable of surviving this process are called the thermodurics. Among these thermodurics, some might be capable of growing under refrigeration conditions. These pasteurization surviving psychrotrophs also termed thermoduric psychrotrophs are of high of high public health and economic significance as refrigerated storage is the most widely recommended storage environment for milk and milk products. In an attempt to understand the thermoduric psychrotrophic profile of local dairy environment with special emphasis to pasteurized milk, a total of 57 samples constituted by 42 samples of pasteurized milk, seven samples of milk products, two raw milk samples from BMC and six dairy equipment swabs were assessed in this study. Thermoduric psychrotrophic organisms were found only in 10.5 per cent of the total samples and 14.3 per cent of pasteurized milk samples tested yielding six thermoduric psychrotrophic isolates. From these isolates, four were selected and genotypically identified as Aeromonas caviae, Moraxella osloensis, and two different strains of Carnobacterium maltaromaticum. Their nucleotide sequences were deposited in the NCBI database under accession numbers MT071634, MT158663, MT158664 and MT158665 with strain numbers as DMV01, DMV03, DMV05 and DMV06 respectively. On assessing these isolates for motility, haemolytic activity, biofilm forming, defect causing abilities and antibiotic susceptibilities, wide variations were observed in between them. Out of the six isolates, two Gram negative isolates namely A. caviae and M. osloensis were assessed further for heat resistance at 63oC, resistances to boiling process, pH, ability to grow in milk under room and refrigerated storage. Though both of them could survive the normal LTLT pasteurization process, marked difference was evident in their resistance pattern. The D-value of A. caviae DMV01 at 63oC was found to be 4min 38s, much lower than that of M. osloensis DMV03 (25min 18s). Both these organisms could not survive boiling even for one second. Despite their high heat resistance both of them were found to be sensitive to exposure to low pH. On assessing the generation time, a clear demarcation was evident in the growth curve of A. caviae DMV01 and M. osloensis DMV03. Considering the higher growth rate and biofilm forming potential of A. caviae DMV01, it was further assessed for its ability to form biofilms on glass surface and stainless steel strips. On subjecting the A. caviae DMV01 biofilms formed on stainless steel strips to a laboratory level simulation of CIP regime, 17 per cent of the cells survived on using the CIP solutions at 0.5 per cent whereas none of the cells survived CIP with 1 per cent solutionsThesisItem Open Access STANDARDIZATION OF ENCAPSULATION TECHNIQUE FOR EFFECTIVE PROBIOTIC DELIVERY(COLLEGE OF DAIRY SCIENCE AND TECHNOLOGY MANNUTHY, 2022-02-11) JITHU RAPPAI; A.K. BEENAA potentially probiotic lactic acid bacterium was isolated from human breast milk. Based on biochemical characterization and 16SrRNA sequencing, the isolate was identified as Pediococcus pentosaceus DM101, the sequence of which is deposited in NCBI with accession number MK774704. Acid and bile tolerance studies indicated that Pediococcus pentosaceus DM101 can withstand pH 3.0 and 0.6 % (w/v) bile salt for four hours. The isolate exhibited an auto-aggregation value of 67.9±0.74% and a cell surface hydrophobicity values of 60.7±0.67% with xylene signifying the good adhesion potential for the isolate. Inability to cause haemolysis and liquefy gelatin suggests the possible absence of virulence factors. Antibiogram revealed the isolate to be resistant to Vancomycin, Methicillin, Bacitracin, and Cephalosporin group of antibiotics. Congo red assay confirmed the exopolysaccharide (EPS) producing nature of the isolate. DPPH(2,2-diphenyl picrylhydrazyl) assay of the cell pellet and cell-free supernatant revealed an IC 50 value of 61.57 and 20.78mg/ml, endorsing its radical scavenging potential. Based on survival per cent, encapsulation by extrusion was optimized with 2.0% sodium alginate as gelling agent, 0.1 M CaCl2 as hardening solution and gelling time 20 minutes. The alginate beads so obtained were characterized in terms of swelling ratio and dissolution behavior. The alkaline pH 8.0 facilitated the release of bioactive components by 4h, whereas acidic pH 2.0 did not release the contents even after 8h. When exposed to simulated gastrointestinal conditions, the survival rates for encapsulated and non-encapsulated cells were 86.11% and 15.86% respectively. On 60th day of storage, log reduction of viable cells in encapsulated form at 4°C and -18°C was 1.10 and 3.30 respectively. For the same time period, corresponding values were 9.17 and 9.30 for non-encapsulated cells. The observations endorse encapsulation as an effective tool for sustaining viability when exposed to challenging environment.ThesisItem Open Access BIOREMEDIATION POTENTIAL OF LACTIC ACID BACTERIA AGAINST CADMIUM AND LEAD(COLLEGE OF DAIRY SCIENCE AND TECHNOLOGY MANNUTHY, THRISSUR, 2021-12-31) MARIYA DIVANSHI A S; Aparna Sudhakaran VCadmium and lead tolerant lactic acid bacteria were isolated from dairy effluent, soil sample, chikoo fruit (Manilkara zapota), breast milk and neonatal fecal matter and optimised their bioremediation potential against cadmium and lead. 16srRNA sequencing confirmed the isolates as Lactobacillus plantarum, Lactobacillus fermentum, Fructobacillus tropaeoli, Pediococcus pentosaceus and Weissella confusa respectively. The nucleotide sequences so obtained were deposited in NCBI with accession numbers MT158675, MT158674, MT158673, MT158672 and MT158671. Minimum inhibitory concentrations (MIC) of the five isolates were evaluated and the highest MIC of 600 mg/L and 2500 mg/L had shown by Weissella confusa for both cadmium and lead respectively. Multiple antibiotic resistance index was also maximum for Weissella confusa. Evaluation of biosorption potential revealed that out of all the isolates, highest biosorption efficiency for cadmium was recorded by Weissella confusa (14.20%) and for lead by Lactobacillus plantarum (51.40%). Both of them were exopolysaccharide producers. Scanning electron microscopy also confirmed the adsorption of metal ions to the cell surface. Therefore, Weissella confusa and Lactobacillus plantarum were selected for optimization of different factors. Five factors namely pH, metal concentration, inoculum rate, temperature and contact time affected the lead biosorption significantly. However, in the case of cadmium biosorption, only inoculum rate, metal concentration and contact time had a significant effect. As suggested by the two factor interaction response surface model, the optimized condition for cadmium biosorption by Weissella confusa was one per cent inoculum rate, 50 mg/L concentration of cadmium and 30 h of contact time. The quadratic model fitted for lead biosorption recommended the optimum condition as pH 7, 30⁰C temperature of incubation, one per cent inoculam rate, 50 mg/L concentration of lead and 30 h of contact time were the optimum conditions for effective biosorption by Lactobacillus plantarum.ThesisItem Open Access EVALUATION OF FUNCTIONAL CHARACTERISTICS OF EXOPOLYSACCHARIDE PRODUCING LACTIC ACID BACTERIA(COLLEGE OF DAIRY SCIENCE AND TECHNOLOGY MANNUTHY, THRISSUR, 2020-11-01) AMRUTHA T A; A K BeenaEPS producing LAB were isolated from indigenous sources suchas goat milk, tender-coconut water, Vechur cow milk, passion fruit and potato. All the five isolates were biochemically characterised and 16SrRNA sequencing identified the isolates as Pediococcus pentosaceus, Weissella cibaria, Lactobacillus fermentum, Weissella cibaria and Lactococcus lactis respectively. Pediococcus pentosaceus, from goat milk, Weissella cibaria from tender coconut water, Weissella cibaria from passion fruit and Lactococcus lactis from potato are deposited in NCBI with accession no MK368400, MH782084,MK368397 and MK368420 respectively. As a part of assessing the probiotic potential, isolates were exposed to the harsh conditions of acid and bile. Only P.pentosaceus and W.cibaria (passion fruit) showed growth even after 3h of exposure to pH 2.0. All the isolates except L.lactis showed remarkable tolerance to 0.6% bile salts .To evaluate the adhesion potential cell surface hydrophobicity (CSH) and auto aggregation were determined. The maximum value for CSH(89.2%) and auto aggregation(90%) was exhibited by P.pentosaceus. The extent of increase in autoaggreagtion percentage on extended incubation was also maximum for this isolate. The observation of this isolate as non-haemolytic and negative for gelatin liquefaction indicates the possible absence of virulence factors.DPPH scavenging activity of P.pentosaceus was found to be 35.48%.P.pentosaceus produced EPS maximally when grown in nutrient broth that was supplemented with two percent maltose at pH 7.0. The optimum rate of inoculation was two percent.EPS recovery .was maximum after incubation at37 0C for 24h .DPPH assay showed that, 0.03mg of EPS exhibited antioxidant activity of 38.71%. Technological properties of the isolate were evaluated by looking into rate of acid productionand the physicochemical characteristics of the products prepared using the isolate.Syneresis value reduced remarkably when P. pentosaceous was included as starter. The observations in this study endorses the use of P. pentosaceus as an adjunct culture for the preparation of fermented milk products with better textural properties.
