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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 Chemistry × End date: 2014 × Start date: 2014 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    COMPARATIVE APPRAISAL OF PHYSICAL, CHEMICAL, INSTRUMENTAL AND SENSORY EVALUATION METHODS FOR MONITORING OXIDATIVE DETERIORATION OF GHEE
    (AAU, Anand, 2014) MEHTA, BHAVBHUTI MANOJBHAI; Aparnathi, K. D.
    Ghee is the most famous traditional dairy product in India, now also gaining popularity in Asian countries as well as other continents like Australia, Europe and America. This fat rich dairy product is highly regarded for typical pleasing flavor. Ghee, being a lipid, prone to oxidation. Lipid oxidation is a degradation process considered to be a major cause of deterioration in the quality of fat products. It imparts rancid and unpleasant flavors to the products and thus decreases their organoleptic value. The reaction of fat oxidation is autocatalytic and occurs in two stages. In primary stage of the fat oxidation reaction between the unsaturated fatty acid and oxygen leads to formation of hydroperoxides and during secondary stage of the reaction the hydroperoxides decomposed into off smelling volatile compounds. This is very complex process that resuh in the formation of several different compounds. Therefore, there is no single method to measure all these compounds, consequently, the use of more than one testing method is recommended to monitor oxidative changes taking place in lipid. Numerous physical, chemical and instrumental methods have been reported to measure oxidative deterioration of oils and fats. The selection of appropriate analytical method is very essential to obtain correct information about oxidative deterioration of product like ghee. Analytical methods most widely reported are weight gain, conjugated dienes, Kreis number, iodine value, free fatty acids content, peroxide value, TBA value, p- Anisidine value, TOTOX value, Carbonyl value and Rancimat. However, no systematic work has been carried out so far for selection of the most appropriate methods to monitor oxidative deterioration of ghee. Therefore, this study was undertaken with a goal to compare performance of selected physical, chemical and instrumental methods to evaluate oxidative deterioration of ghee and to establish correlation between results obtained by these methods with results obtained by sensory evaluation of the ghee for flavor score. The entire work of study was divided as (1) selection of methods used for determination of peroxide value of ghee, (2) evaluation of methods used for monitoring oxidation of ghee on the bases of changes taking place during primary stage of lipid oxidation, (3) examination of methods used for monitoring oxidation of ghee on the bases of changes taking place during secondary stage of lipid oxidation, (4) testing of Rancimat for suitability to study oxidation of ghee, (5) comparison between performance of the method selected from stage of primary oxidation, method selected from secondary stage of oxidation and Rancimat to study oxidative deterioration of ghee and (6) work out the correlation between the results obtained by accelerated storage study and the results obtained from sensory evaluation of ghee for flavor score on storage at normal temperature. In selection of methods for determination of chemical changes taking place during primary stage as well as secondary stage of oxidation in ghee, accelerated storage study was employed. The samples of ghee were prepared by creamy butter method stored at 80°±2°C and monitor for chemical changes using selected methods at regular interval of every 48 hours. The samples of ghee were simultaneously analyzed for changes in flavor score by sensory evaluation using 9 point hedonic scale. For testing the suitability of Rancimat to study the oxidative deterioration of ghee, oxidation curves for the ghee were obtained at 90°C, 100°C, 110°C and 120°C and Arrhenius plots were obtained to predict the shelf life of ghee. Simultaneously ghee samples were also stored at 35°±2°C and monitor for changes in flavor score by sensory evaluation using 9 point hedonic scale at an interval of 10 days. Amongst the BIS, AOAC, AOCS/IUPAC, FOX and IDF methods used to monitor the peroxide formation in ghee, the FOX method was found most consistent. Moreover, the best correlation between changes in flavor score of ghee and peroxide formation was given by FOX method. Amongst the weight gain. Conjugated dienes, Kreis number. Iodine value, free fatty acids content and Peroxide value by FOX method based on chemical changes in the primary stage of the oxidation of ghee, except the FOX method no other method gave significant correlation with changes in flavor score of ghee during storage. Amongst the TBA value, p-Anisidine value, TOTOX value and Carbonyl value based on chemical changes in the secondary stage of the oxidation of ghee, the carbonyl value was found consistent. In addition it gave the highest correlation with changes in flavor score of ghee during storage. The changes in temperatures of Rancimat were highly correlated with induction period of ghee samples and changes in its flavor scores on storage at 80°±2°C. The predicted shelf life of ghee at 80°±2°C obtained from the prediction models prepared using the results of peroxide value by FOX method and carbonyl value of the ghee stored at 80°±2°C and that obtained from Rancimat was almost in corroboration with the actual shelf life of ghee stored at 80°±2°C. The predicted shelf life of ghee at 35°±2°C obtained from the prediction models prepared using the results of peroxide value by FOX method, carbonyl value and flavor score of the ghee stored at 80°±2°C was almost in corroboration with the actual shelf life of ghee stored at 35°±2°C. However, the predicted shelf life of ghee at 35°±2°C obtained from Rancimat was 2.47 times higher than the actual shelf life of ghee stored at 35°±2°C. Therefore, it appeared from the results that use of peroxide value by FOX method, carbonyl value and flavor score of ghee on storage at 80°±2°C are promising for predicting shelf life of ghee at normal temperature, but use of Rancimat does not appear promising to predict the shelf life of ghee on storage at normal temperature.
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    ThesisItemOpen Access