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Subject: Dairy Microbiology × End date: 2023 × Start date: 2020 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    DEVELOPMENT OF REGION-SPECIFIC PHAGE RESISTANT DAIRY STARTER COMBINATIONS FOR THE STATE OF KERALA
    (VERGHESE KURIEN INSTITUTE OF DAIRY AND FOOD TECHNOLOGY MANNUTHY, THRISSUR, KERALA VETERINARY AND ANIMAL SCIENCES UNIVERSITY, 2022-12-08) ARCHANA CHANDRAN; Dr. A.K Beena
    A total of 200 curd samples were collected from the two agroecological zones of Kerala covering the districts of Idukki, Ernakulam, Thrissur, Palakkad and Wayanad. Consumer preference for medium low acid curd was significantly higher than high acid curd in both zones. Average acidity of curd samples in per cent lactic acid was1.65 ± 0.06 in high range and1.49± 0.04 in central mid land. The average counts of coliforms, S.aureus (coagulase positive) and yeast and mold in the samples were higher than the permissible limits prescribed by FSSAI in both zones. The predominant lactic acid bacteria isolated from curd samples were L.plantarum (26 per cent) followed by L.fermentum (22 per cent). The presence of E.faecaliswas detected at 31 per cent level in central midland. Detection of virulence genes gel E and asa 1 in E.faecalis isolates from curd samples is a safety concern. Study on the yeast microflora of curd suggested the synergistic association of yeast and LAB to be decisive of technotextural properties of curd. Lactose fermenting yeasts like Kluyveromyces marxianus, Kluyveromyces lactis and Pichia kudriavzveii were also isolated from the curd samples. Bacteriophages attacking Lactobacillus sp were detected in effluent samples at a level of 105-107 PFU/ml. The four Lactobacillus phages belonged to Siphoviridae family. Seventy three per cent of LAB strains in the study were found to be phage resistant. L.fermentum (ADMH 12) and Pichia kudriavzveii (Y01) were combined in 1:1 ratio for developing phageresistant starters. Overall acceptability of curd (7.58 ± 0.21) was significantly higher for the product prepared using starter combination than those prepared using single starters. Skim milk lactose combination (1:1) was found to be the ideal cryoprotectant for ADMH12 and skim milk-trehalose combination (1:1) for Y01