FDSC 310 Lecture 2: Postharvest technology lecture 2
10 Oct 2017
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Need to maintain it at minimal level to sustain life but keep rate of metabolic activities low. Aerobic (presence of oxygen) yields higher energy, anaerobic (limited oxygen, leads to fermentation) results in off-flavour. Respiration rate is expressed in oxygen consumed, carbon dioxide released or heat liberated per unit weight of the produce at a given time. O2 basis:mg or ml of o2 consumed / kg produce/ h. Co2 basis: mg or ml co2 produced/ kg produce / h. Heat basis: kcal or kj / ton (produce) / day. Aerobic oxidation of glucose requires oxygen, inorganic phosphate gr, catalyst/promoters (enzymes, coenzymes, metal ions) Step 1 : glycolysis (emp pathway) conversion of glucose to pyruvate forms atp (does not require oxygen) yields 8 atp. Step 2: tca cycle or krebs cycle or citric acid cycle (yields 38 atp) Pyruvate converted to carbon dioxide and water. involves transfer of electrons in mitochondria through etc electron transport chain.
