Fruit tissues

Fruit tissue was homogenized in four volumes of ethanol and refluxed for 30 min in a boiling water bath. The homogenate was passed through a glass filter and the residue washed sequentially with 500 ml of 80% of ethanol and 500 ml of ethanol. The powder (AIS) was dried over P2O5 in vacuo. 

Barat, J.M., Fito, P., and Chiralt, A. 2001. Modelling of simultaneous mass transfer and structural changes in fruit tissues. J. Food Engineer. 49, 77-85. 

Gekas, V., Oliveira, F.A.R., and Crapiste, G.H. 2002. Non-Fickian mass transfer in fruit tissue. In Engineering and Food for the 21st Century (J. Welti-Chanes, G.V. Barbosa-Canovas, and J.M. Aguilera, eds), pp. 193-215. CRC Press, Boca Raton, FL. 

The possibility that many organic compounds could potentially be precursors of ethylene was raised, but direct evidence that in apple fruit tissue ethylene derives only from carbons of methionine was provided by Lieberman and was confirmed for other plant species. The pathway of ethylene biosynthesis has been well characterized during the last three decades. The major breakthrough came from the work of Yang and Hoffman, who established 5-adenosyl-L-methionine (SAM) as the precursor of ethylene in higher plants. The key enzyme in ethylene biosynthesis 1-aminocyclopropane-l-carboxylate synthase (S-adenosyl-L-methionine methylthioadenosine lyase, EC 4.4.1.14 ACS) catalyzes the conversion of SAM to 1-aminocyclopropane-l-carboxylic acid (ACC) and then ACC is converted to ethylene by 1-aminocyclopropane-l-carboxylate oxidase (ACO) (Scheme 1). 

Citrus paradisi fruit tissue chalcone cyclase protein — - Y[64]... 

Thorpe TA, Maier VP, Hasegawa S (1971) Phenylalanine ammonia-lyase activity in citrus fruit tissue cultured in vitro. Phytochemistry 10 711-718... 

ACC 71 synthase, i. e. (S)-adenosylmethionine methylthioadenosine lyase (EC 4.4.1.14), has been purified from several plant tissues [116]. Recently, ACC synthase cDNA clones have been isolated and sequenced from wounded fruit tissues of tomato, winter squash, zucchini, ripening apple and tomato fruit. Using the polymerase chain reaction (PCR), four different ACC synthase gene fragments were obtained by amplification of cDNA derived from mRNA of tomato... 

Ethylphenoxy)triethylamine and 2-(3,4-dimethoxyphenoxy)triethylamine markedly reduce the biosynthesis of limonoids in citrus leaves, presumably by inhibition of cyclase activity. Radio-tracer studies have revealed that limonoids are synthesized in the leaves of citrus and transported to the fruit. The fruit tissue does not appear to be capable of the de novo synthesis of limonoids from acetate or mevalonate. 

The balance of the evidence available suggests that the activity of endogenous cellulase in degrading, primary-wall microfibrils does not contribute significantly to fruit tissue-softening accompanying ripening. 

The literature contains considerable data on inorganic constituents in fruit tissues. However, most of the data pertain to apples and grapes, and relatively little information is available on other fruits. A summary of typical averages of mineral contents of some common fruits is presented in Table VI. 

The production of ethylene in fruit tissue and in small amounts in leaves may justify its consideration as a hormone, functioning in the gaseous state, Cherimoyas and some varieties of pear produce 1000 times the effective physiological concentration. Ethylene formation is closely linked to oxidation and may be centered in the mitochondria. Its effects are to promote cell-wall softening, starch hydrolysis, and organic add disappearance in fruits—the syndrome known as ripening. Ethylene also decreases the geotiopic responses of stems and petioles. 

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