Er. K. LAVANYAEEDA GOWTHAMI, Er2017-10-122017-10-122015http://krishikosh.egranth.ac.in/handle/1/5810032999D5206Orange (Citrus sinensis), belonging to Rutaceae family evolved in the South East Asia and has excellent nutritive, medicinal and food values, may prevent and reduce the risk of degenerative and chronic diseases due to antioxidant activity. Readyto-eat/use and/or minimally processed food products have become popular due to their convenience, high value, unique sensory characteristics and health benefits. The change in food consumption patterns from ensuring an adequate supply of calories and nutrients with an increased emphasis on quality and consumer demand are required. Extending the shelf life of orange segments is important for domestic and export market. A study was undertaken to establish the most effective gas composition and packaging material for modified atmospheric packaging to extend the shelf life of orange segments. Fresh and sorted orange fruits were sanitized, dried, peeled and segmented. The citric acid treated and untreated orange segments (150 g) were packed under three different gas compositions i.e., 8% O2 + 15% CO2 + 77% N2 (G1), 5% O2 + 10% CO2 + 85% N2 (G2), 3% O2 + 5% CO2 + 92% N2 (G3) in different packaging materials like low density poly ethylene (LDPE, 60 µm), polypropylene (PP, 32 µm) and poly vinyl chloride (PVC, 20 µm). Physico-chemical, microbial and sensory characteristics were monitored at 50C for 25 days. The results showed that oxygen concentration gradually decreased but the carbon dioxide concentration gradually increased and reached a steady state concentration for both treated and untreated orange segments. The untreated orange segments could reach the steady state concentration at an early storage period compared to treated orange segments. The physiological loss in weight of treated orange segments packed in LDPE covers under G2 gas composition stored at 50C was less. The firmness and pH of treated orange segments packed in LDPE covers under G2 gas composition slightly increased and then decreased. The TSS and titratable acidity of treated orange Name of the Author : E. GOWTHAMI Title of the thesis : “READY-TO-EAT ORANGE SEGMENTS BY MODIFIED ATMOSPHERE PACKAGING UNDER REFRIGERATED STORAGE” Degree to which it is submitted : Master of Technology Faculty : Agricultural Engineering Major field of study : PROCESSING AND FOOD ENGINEERING Major Advisor : Er. K. LAVANYA University : Acharya N.G Ranga Agricultural University Year of Submission : 2015 segments packed in LDPE covers under G2 gas composition was decreased during storage period. The highest retention (reduction in ascorbic acid content was low) of ascorbic acid content was observed in treated orange segments packed in LDPE covers under G2 gas composition. The microbial count was less in treated orange segments packed with LDPE covers under G2 gas composition stored at 50C compared to PP, PVC covers and G1 & G3 gas compositions and control. In sensory evaluation, the LDPE packed, citric acid treated orange segments stored at 50C scored highest rating on hedonic scale by panelists in terms of visual appearance (4.45), aroma (4.47), texture (4.38), sweetness (4.3) and product acceptability (4.58). The shelf life of citric acid treated and untreated orange segments packed with LDPE covers under G2 gas composition can be enhanced up to 25 & 20 days respectively in comparison to only 4 days shelf life of control. However, the quality of LDPE packed treated orange segments under G2 gas composition stored at 50C is more acceptable. Keywords: Orange segments, Pretreatment, Modified atmosphere packaging, Packaging materials, Storage.en-USnullThesis