Geethu M creator Saji Gomez (Guide) text Vellanikkara Department of Post Harvest Technology, College of Agriculture 2022 monographic 163p. Avocado is a subtropical fruit crop, belonging to the family Lauraceae, and is rich in proteins, vitamins, minerals and monounsaturated fatty acids such as oleic acid, contributing to its high nutritive and therapeutic value. Even though there are a large number of genotypes with widely varying characteristics, inadequate characterisation and identification result in the lack of awareness, improper utilisation and insufficient post harvest management of avocado. Hence, the present study titled, „Post harvest characterisation and management of avocado (Persea americana Mill.)‟ was carried out in the Department of Post Harvest Technology, College of Agriculture, Vellanikkara during 2018-2021. The main objectives of the study were to characterise avocado accessions collected from different parts of Kerala and to evaluate the effect of post harvest management practices to extend the shelf life of avocado fruits and to study the effect of food additives on the quality of frozen slices, fruit pulp, freeze dried fruit powder and subsequently to standardise an instant avocado fruit shake. For the characterisation of avocado genotypes, 27 accessions were collected, among which 14 accessions were from RARS, Ambalavayal in Wayanad and 12 from Kanthaloor in Idukki and one accession was collected from Thanniyam in Thrissur. Characterisation of avocado genotypes based on the horticultural and biochemical traits, accession 25 from Idukki had comparatively higher TSS, vitamin C, total carbohydrates, total flavonoids, oleic acid, calcium, potassium, iron, total ash and crude fibre content. Hence, accession 25 was selected for subsequent post harvest management studies. Antioxidant activity of the methanolic extract of fresh fruit of accession 25 was evaluated by DPPH, FRAP and ABTS assays. Greatest free radical scavenging activity was observed in ABTS assay with lowest IC50 value of 0.10 μg/mL. Fresh and mature avocado fruits, surface sanitised with 2 ppm ozone and pretreated with 2 % calcium chloride, followed by shrink packaging with 25 μ polyolefin film and subsequently stored in refrigeration (T8) as well as cool chamber (T9) were found to be the ideal storage conditions with longest shelf life of 27 days. Calcium chloride pre-treated fruits with shrink packaging, stored under refrigeration had lowest physiological lossin weight, respiration rate, ethylene evolution rate and decay per cent, with better retention of firmness. Fruits of this treatment retained significantly higher total carbohydrates, total protein and total phenols during storage. Avocado slices pre-treated with 40 % sucrose, ascorbic acid (0.5 %) and potassium metabisulphite (0.1 %), quick frozen to -20 ºCin 30 minutes followed by packing in 200 gauge LDPE pouches and held under frozen temperature (-18 0C) was the most ideal pre-treatment for storage. This treatment recorded significantly higher TSS, vitamin C, total carbohydrates, total protein and organoleptic acceptability throughout storage and lowest water activity, peroxide value and microbial population. For preparation and storage of avocado pulp, pre-treatments with ascorbic acid (0.5%) and KMS (0.1%) followed by vacuum packaging LDPE bags (T10) as well as in glass jars (T12), stored under refrigeration resulted in longest shelf life and better quality. Total protein, total phenols, total carbohydrate, total fat, viscosity and organoleptic scores were highest in these treatments with lowest water activity, polyphenol oxidase activity and microbial population during storage. For preparation of avocado fruit powder, addition of 5% maltodextrin, ascorbic acid (1%), tricalcium phosphate (0.15%), EDTA (0.05%) and potassium sorbate (0.05%) followed by freeze drying at -70 ºCand 100 mtorr vacuum for 36 hours followed by packing in LDPE laminated aluminium pouches (T14) and glass jars (T16) stored under refrigeration were the ideal methods with longest shelf life and quality. Significantly higher bulk density, solubility, colour value L*, TSS, vitamin C, total carbohydrates, total fat and organoleptic scores were recorded in these treatments during storage along with lowest hygroscopicity, colour value a* and b*, peroxide value, water activity and microbial population. An instant avocado shake was standardised by combining avocado fruit powder with skimmed milk powder, sucrose and water in the proportion of 1:2:1:2 with appealing appearance, light yellowish colour, unique blend of taste and flavour of avocado fruit and skimmed milk powder. PhD Post Harvest Technology Avocado Persea americana Mill 631.56 GEE/PO PhD https://krishikosh.egranth.ac.in/handle/1/5810194740 https://krishikosh.egranth.ac.in/handle/1/5810194740