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Anand Agricultural University, Anand

Anand Agricultural University (AAU) was established in 2004 at Anand with the support of the Government of Gujarat, Act No.(Guj 5 of 2004) dated April 29, 2004. Caved out of the erstwhile Gujarat Agricultural University (GAU), the dream institution of Sardar Vallabhbhai Patel and Dr. K. M. Munshi, the AAU was set up to provide support to the farming community in three facets namely education, research and extension activities in Agriculture, Horticulture Engineering, product Processing and Home Science. At present there seven Colleges, seventeen Research Centers and six Extension Education Institute working in nine districts of Gujarat namely Ahmedabad, Anand, Dahod, Kheda, Panchmahal, Vadodara, Mahisagar, Botad and Chhotaudepur AAU's activities have expanded to span newer commodity sectors such as soil health card, bio-diesel, medicinal plants apart from the mandatory ones like rice, maize, tobacco, vegetable crops, fruit crops, forage crops, animal breeding, nutrition and dairy products etc. the core of AAU's operating philosophy however, continues to create the partnership between the rural people and committed academic as the basic for sustainable rural development. In pursuing its various programmes AAU's overall mission is to promote sustainable growth and economic independence in rural society. AAU aims to do this through education, research and extension education. Thus, AAU works towards the empowerment of the farmers.

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Subject: Dairy Microbiology × Author: BAXI, NISHITH J. × End date: 2009 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    PERFORMANCE EVALUATION OF DAHI MADE WITH LEAST OVERACIDIFYING STREPTOCOCCOS THERMOPHILUS STRAINS INDIVIDUALLY AND IN ASSOCIATION WITH LACTOBACILLUS ACIDOPHILUS LBKI4
    (AAU, Anand, 1996) BAXI, NISHITH J.; SANNABHADTI, S. S.
    This investigation was planned and carried out to evaluate the performance of two promising strains of Streptococcus thermophilus viz., MD5 (C1) and NDI6 (C3) singly or in combination with Lactobacillus acidophilus LBKI4 strain (LBKI4 + MD5 (C2) and LBKI4 + NDI6 (C4)) to assess their feasibility for commercial manufacture of least overacidifying dahi from available cow milk, buflalo milk and mixed milk having equal proportion of cow and buffalo milk. The prepared dahi was subjected to sensory analysis to evaluate its acceptability as least overacidifying dahi by a panel of seven expects. For studying different attributes, dahi was manufactured from cow milk, buffalo milk and mixed milk adjusted to their minimum required total solids. After standardization, the milk was subjected to homogenization (single stage, 100 kg/cm2) after pre-heating to 60°C . Then the homogenized milk was heated to 90°C for 5 min and cooled to 40°C. The heat treated milk was further divided into four equal parts. To each of these four lots (MD5 (C1), NDI6(C3), strains were added as inoculum individually at the rate of three per cent, MD5 + LBKI4 (C2), NDI6 + I4 (C4) strains were added as inoculuvw in combination at the rate of three per cent (2:1 proportion). The inoculated milk samples were filled in the sanitized polystyrene cups having lid and then incubated at 39°C ±1°C till it reached the acidity of 0.75 per cent lactic acid. To study the physico-chemical, microbiological and organoleptic changes taking place along with the keeping quality of dahi under room temperature, the samples were stored at 37 ± TC and analysed at the interval of 0 h, 36 h, and 60 h. Similarly for study under refrigerated condition samples were stored at 7 ± 1°C and analysed at the interval of 0, 10,20 and 30 days of storage. The treatment under study were evaluated by monitoring the change in pH, level of lactic acid produced, change in free fetty acids, total protein and equivalent soluble protein, total solids, change in counts of contaminants like coliform, yeasts and molds, proteolytic and lipolytic coimt along with the starter population and sensory evaluation. In the fresh product the pH ranged from 5.24 (C3M2) to 4.59 (C2M1) and the level of acidity ranged 0.60 (C3M1) to 0.85 (C2M2) (per cent lactic acid). The increase in free fatty acids content varied from 1.62 (C4M3) to 2.64 (C4M1) μ eq./g and total solids (percentage) content varied from milk to milk 15.32 (C3M2) to 12.21 (C3M1). The total nitrogen calculated as protein equivalent varied from 3.1319 (C1M1) to 3.8937 (C3M2) and soluble nitrogen as protein equivalent varied from 0.78 (ClMl) to 0.89 (C1M2, C2M2, C3M3,). The coliform and Yeasts and Molds count expressed as c.fu. per ml ranged from 2.4025 (C4M2) to 13.987 (C3M3) and 1.00 (C2M2) to 36.56 (ClMl)respectively. Same way the starter population expressed in log colony forming units (c.fu.) per ml varied from 9.83 (C3M3) to 10.41 (C3M1) and 8.74 (C2M1) and 9.00 (C2M3) for Sc. thermophilus and Lb. acidophilus respectively. The parameters under study did not show much variation in total protein, total solids. There had been increase in acidity, free fatty acids, starter population during the dahi preparation. The shelf-life of all combinations of dahi were assessed through monitoring pH, acidity, free fetty acids, equivalent soluble protein, total solids, starter population, coimt of contaminating organisms and sensory evaluation. During storage at ambient (37±1°C ) temperature the change in pH varied from 3.93 (C2M1, C3M1) to 4.31 (C3M3), titratable acidity (expressed as per cent lactic acid) varied from 0.94 (C3M1) to 1.68 tC4M2), free fatty acids varied (μ eq./g) from 2.09 (C2M3, C1M3) to 4.59 (C4M2), per cent total solids varied from 12.34 (C3M1) to 15.28 (C1M2), equivalent soluble protem per cent varied from 0.78 (ClMl) to 0.99 (C1M2, C2M2), coliform count(c.f.u./ml) varied from 5.11 (ClMl, C3M1) to 13.987 (C1M3), yeasts and molds count (c.f.u./m]) varied from 37.577 (C2M1) to 155.75 (C2M3), Proteolytic count (c.f.u./ml) varied from 0.0 (ClMl, C1M2, C1M3, C2M3, C4M3) to 33 (C3M3), Upolytic count (c.£u./ml) varied from 0.00 (C3M2, C4M2) to 10.0 (C1M2, C2M2, C2M3) at 60 h of storage. The starter population (log c.f.u./ml) varied from 6.72 (C1M3) to 11.42 (C2M2) and 8.89 (C2M1) to 9.20 (C4M3) for Sc. thermophilus and Lb. acidophilus respectively at 60 h of ambient temperature storage. During refrigerated storage the change in pH varied from 4.45 (C2M3) to 5.40 (C3M2), titratable acidity (expressed as per cent lactic acid) varied from 0.73 (ClMl) to 1.09 (C4M2), free fetty acids (n eq./g) varied from 2.01 (C2M3) to 2.87 (C2M2), per cent total solids varied from 12.29 (C3M1) to 15.39 (C2M2), equivalent soluble protein per cent varied from 0.49 (C4M1) to 0.86 (C2M3), coliform counts (c.fu./ml) varied from 3.20 (C3M1) to 9.01 (C2M2, C4M2), yeasts and molds count (c.fu./ml) varied from 4.00 to 144.0, proteolytic count (c.fu./ml) varied from 0.00 to 20.00, lipolytic count (c.fu./ml) varied from 0.00 (C1M3) to 6.70 (C2M1, C2M2, C3M1, C3M2, C4M2) at 30 days of storage period. The starter population (log c.f.u./ml) varied from 9.37 (C1M3) to 10.14 (C2M2) and 8.48 (C4M3) to 8.81 (C2M1) for Sc. thermophilus and Lb. acidophilus respectively after 30 days of refrigerated storage. Total sensory score out of 30 declined from 25.20 (0 h) to 20.30 (60 h) at ambient temperature storage whereas at refrigerated storage it declined from 25.20 (0 day) to 20.68 (30 day) due to decrease in the scores of flavour, body and texture and colour and appearance. The buflfelo milk inoculated with mixed culture C2 (MD5 +LBKI4) gave the product with least overacidifying property, which we can keep for 60 h at ambient temperature storage. The single culture C1(MD5 strain of 5c. thermophilus) proved one of the best single starter culture with respect to least overacidifying property. Based on the above observations cultures oi Sc. thermophilus (MD5) singly and its combination with Lb. acidophilus (LBKI4) can be recommended as least overacidifying cultures for preparation of dahi.