Effect of thermal processing on the stereoisomerisation of major carotenoids and vitamin A value of carrots

Occurrence of cis-Isomers of Provitamin A in Brazilian Fruits

“…However, in 52 samples of processed tomato products, varying amounts of 13-cis-and 9-cis-@-carotene were found, reaching high levels in some samples. Formation of cisisomers as a consequence of heat treatment has been reported by several authors (Gortner and Singleton, 1961; Panalaks and Murray, 1970; Sweeney and Marsh, 1971; Lee and Ammerman, 1974; Ogunlesi and Lee, 1979;Khachik et al, 1986;Quackenbush, 1987; Schwartz, 1987, 1988; Lawrence et al, 1988). Thus, contrary to fresh fruits, significant amounts of cisprovitamins may be present in processed fruits, making their separation and quantitation in provitamin A determination important.…”

Effects of various traditional processing methods on the all-trans-β-carotene content of orange-fleshed sweet potato

“…Retention is defined as the proportion of carotenoids remaining in the processed sweet potato root in relation to the amount of carotenoids originally present in the sweet potato. Loss of solids during processing may lead to an overestimation of the retention values during processing if not accounted for (Ogunlesi and Lee, 1979;Rodriguez-Amaya, 1997). In the present study, the retention of all-trans-b-carotene in processed and dried OFSP was calculated based on dry weights of the sweet potato samples, and corrected for changes in DM due to loss of soluble solids, loss or uptake of water, and uptake of fat in the deep-fried samples.…”

Vitamin losses: Retention during heat treatment and continual changes expressed by mathematical models

“…Olunlesi and Lee (1979) measured a 65% decrease in the original b-carotene content during canning of carrots and a 56% decrease for carrots pureed for baby food. A similar observation was also made by Kim and Gerber later.…”