Fruit heating

Hot water treatment was reported to delay carotenoid synthesis and thus yellowing of broccoli florets (at 40°C for 60 min) and kale (at 45°C for 30 min), but did not affect Brussels sprouts (Wang 2000). Hot air treatment (38°C and 95% RH for 24 hr) slightly decreased lycopene and (3-carotene content in tomato fruit (Yahia and others 2007) however, fruit heated at 34°C for 24 hr and stored 20°C developed higher lycopene and (3-carotene than nonheated fruit (Soto-Zamora and others 2005). Moist (100% RH) hot air (48.5 or 50°C) for 4 hr caused injury to papaya and losses in lycopene and (3-carotene, but similar treatment with dry air (50% RH), alone or in combination with thiabendazole, had no effect on lycopene and (3-carotene (Perez-Carrillo and Yahia 2004). High-temperature treatment also suppressed 1-aminocyclopropane-l-carboxylic acid oxidase activity and thus indirectly prevented carotenoid synthesis (Suzuki and others 2005). 

The cautions and concerns stated here are for raw, unprocessed melia fruit. Heat treated melia fruit is the primary article in trade, however, and processing by dry-frying is... 

Canned Fruits and Vegetables. The use of citric acid to bring the pH below 4.6 can reduce heat treatment requirements in caimed fmits and vegetables. In addition, citric acid chelates trace metals to prevent enzymatic oxidation and color degradation, and enhances the flavor, especially of caimed fmits. 

A fruitful approach for velocity computation in the first three zones of jets supplied from outlets with finite size was developed based on the hypothesis that momentum diffuses with distance from the source in the same manner as heat energy." 40 approach, developed by Elrod,Shepelev and Gelman, - and Regenscheit, utilizes the method of superposition of jet momentum from the multiple-jet system. These jets originate from the points with supply air veloc-... 

When o-aminobenzophenone is heated with formamide in the presence of formic acid at 150°C for 20 min, a quantitative yield of 4-phenylquinazoline is obtained. In the absence of formic acid longer heating is necessary. Although this reaction does not proceed with o-acylamidobenzophenones, its extension to other o-acylanilines with aliphatic amides may prove fruitful. 

The important commercial feature of these juices, especially significant with blackcurrant and tomato juices, is their ascorbic acid (or vitamin C) content, of which loss by oxidation is known to be accelerated both by heat and by metal (particularly copper) contamination. The effect of copper has been carefully investigated for pure ascorbic acid", and more recently ascorbic acid in blackcurrant juice and model systems. There are, however, oxidation inhibitors of different kinds (which may themselves be heat-sensitive) present in various fruits, which give differing results. The presence of metals will also affect flavours", may cause discoloration, and may give rise to clouding effects, as in apple juice. ... 

Fruits and vegetables which give off heat of respiration need to have perforated cases so that air may pass through the product. 

Ascorbic acid is photosensitive and unstable in aqueous solution at room temperature. During storage of foods, vitamin C is inactivated by oxygen. This process is accelerated by heat and the presence of catalysts. Ascorbic acid concentration in human organs is highest in adrenal and pituitary glands, eye lens, liver, spleen, and brain. Potatoes, citrus fruits, blade currants, sea buckthorns, acerola, rose hips, and red paprika peppers are among the most valuable vitamin C sources [1,2]. 

The several polymeric metal carbonyls studied have led to some surprisingly high yields [e.g., Fe3(CO),2 and Ruj(CO)j2 in Table IV] but to no substantiated mechanisms. The 17% yield of Fe3(CO),2 in neutron-irradiated Fe(CO)j was interpreted as a reaction of Fe(CO)4 with the Fe(CO)5, but no further evidence is available. The study of Mn2(CO),o has been fruitful (44, 46). The insensitivity of the parent yield MnMn(CO),o to heat indicates that the molecule is formed by a reaction quite early in the sequence, perhaps epithermal. The discovery (46) of a species which reacts rapidly with I2 and exchanges with IMn(CO)5 led to the conclusion that the Mn(CO)5 radical is produced prominently (4.5%) by nuclear reactions in the solid decacarbonyl. The availability of this labeled Mn(CO)5 has made possible several interesting observations about the exchange properties of this radical in the solid (45) and in solution (42). 

Lycopene is a bright red pigment that colors several ripe fruits, vegetables, and flowers. Tomato and tomato products are the main dietary sources of this carotenoid, although it is also found in watermelons, guavas, pink grapefruits, and in small quantities in at least 40 plants. - The absorption of lycopene in the human gut is increased by heat treatment, probably because the breakdown of the plant cells makes the pigment more accessible. ... 

The psubunit has been purified from PGl by ourselves and others and is a heat stable, acidic, heavily glycosylated protein with an apparent molecular mass of 37-39 kD (19, 26). No enzymatic activity has been identified for the protein. The psubunit can be extracted from the cell walls of both green and ripe tomato fruit by high salt buffers (13, 14, 18, 19, 20), and in the latter case is associated with PG2 polypeptide(s) in the form of PGl. Purified psubunit can also associate with and convert PG2 in vitro into an isoenzyme that closely resembles PGl (13, 14, 24). Biochemical studies have shown that in vivo and in vitro formation of PGl by the association of PG2 with the p-subunit alters the biochemical and enzymic properties of the associated catalytic PG2 polypeptide including its pH optima, response to cations and thermal stability (summarized in Table 1). This later property provides a convenient assay for the levels of PGl and PG2 in total cell wall protein extracts. 

---