All flavor components in plants and animal tissues are as a result of cellular metabolism. Since cell structures in plants and animals are different, there exist some similarities and differences of flavor development in these tissues to a certain degree.
A striking similarity is in the production of metabolites by enzymic reactions. Plants and animal tissues undergo physiological reactions at the cellular level which is manifested in food metabolic pathways. The substrates and products of these pathways are compounds that may contribute to the flavor of the tissues. E.g. The production of acetaldehyde in grapes, acyl-amyl acetate in bananas, lactic acid production in meat muscles.
Furthermore, the disruption of cell structure in plant tissues has a profound effect on flavor development that is similar to the effect of membrane disintegration in animal tissues. When cell wall membranes of biological tissues are disrupted, cellular components are released which contribute to the flavor of the tissues. Also during cell disintegration (grinding, milling, macerating, chewing), various compounds which were formerly contained within separate compartments in the cell are liberated. These compounds react with each other and with compounds in the external environment like oxygen, water, saliva, and enzymes, to form a lot of new compounds contributing to the flavor of the food. E.g. The reaction of amylase in saliva with starchy components in tissues during chewing to form sugars which contribute to the sweet taste of cereals and grains.
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4 comments:
I would like to add that:
Plants and animal tissues contain flavorless compounds that act as substrates for enzymic reactions, leading to flavor compound production. These substrates are regarded as flavor precursors. Although these precursors are present in plant and animal tissues, they react in different ways to release different flavors.
Some flavor precursors in plant tissues are bound as glycosides which when hydrolyzed, contributes to flavor (e.g. Terpenyl glycosides in grapes). In contrast, the flavor precursors in animal tissues contribute to flavor as a result of thermal degradation (e.g. meat flavor released during cooking).
Respiration and senescence are post-harvest changes of live plant tissues that contribute significantly to flavor production and a resultant sweet taste. Some plant tissues ripen during respiration to concentrate sugars (e.g. oranges, pineapples), while sugar concentration in other plants occur during senescence (e.g. bananas, tomatoes, papaya).
Animal tissues on the other hand develop characteristic flavors postmortem, leading to their conversion to meat. This involves a decrease in pH of the tissue, depletion of ATP and contraction of muscle tissues during ageing. This ageing process then leads to the the development of desired flavor compounds in the meat.
I thought I should add something to what had already been said.
Flavor development in plant tissues is affected by factors that occur both prior to and after harvest. Factors occurring before harvest such as sunlight exposure, water level, fertilizer usage, pruning, and row-spacing affect flavor quality of plant tissues. The level of maturity and fertilization of the plant at the time of harvest, as well as physiological reactions occurring after harvest, affects the the favor of the plant tissue.
Unlike plants, the factors that affect the flavor development of animal tissues include diet, age, and health of the live animal prior to slaughter. The flavor of meat muscles can be affected by method of preparation, degree of processing, and duration of storage of the meat.
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