Consumption of tomato products has been associated with decreased risk of some cancer types, and the tomato antioxidant, lycopene, is thought to play an important role in the observed health effects. In this study, four carotenoids, trans-lycopene, phytofluene, phytoene, and zeta-carotene, were quantified in tomato products. Samples of raw tomatoes, tomato juice after hot break scalder, and final paste were obtained from two different processing plants over two years. Comparison of carotenoid levels throughout processing indicated that lycopene losses during processing of tomatoes into final paste (25-30 degrees Brix) ranged from 9 to 28%. The initial Brix level of the raw tomatoes appeared to influence the amount of lycopene loss that occurred, possibly due to the differences in processing time required to achieve the final desired Brix level of the paste. In general, no consistent changes in the other carotenoids were observed as a function of processing. The antioxidant activity of fresh tomatoes, tomato paste, and three fractions obtained from these products (i.e., aqueous, methanol, and hexane fractions) was also determined. In both a free radical quenching assay and a singlet oxygen quenching assay, significant antioxidant activity was found in both the hexane fraction (containing lycopene) and the methanol fraction, which contained the phenolic antioxidants caffeic and chlorogenic acid. The results suggest that in addition to lycopene, polyphenols in tomatoes may also be important in conferring protective antioxidative effects.

As part of a program to control the biosynthesis of Solanum glycoalkaloids in potatoes, we used a modified extraction-HPLC assay to measure the -chaconine and -solanine content of commercial and new potato varieties, different parts of the potato plant, and commercial potato products. The improved assay was accomplished by extracting, precipitating, and filtering the hot methanol extract through a 0.45-µ membrane before HPLC analysis. Recoveries of spiked samples ranged from 89 to 95%. The combined -chaconine and -solanine contents of different parts of the new NDA 1725 potato cultivar (in milligrams per 100 g of fresh weight) were as follows: tubers, 14.7; main stems, 32.0; small stems, 45.6; roots, 86; leaves, 145; and sprouts, 997. The -chaconine content of several other potato cultivare ranged from 1.17 to 13.5 mg/100 g of fresh weight and the corresponding a-solanine content from 0.58 to 5.9 mg/100 g of fresh weight. The corresponding values for potato berries were 22.1 and 15.9 mg/100 g of fresh weight, respectively. The total glycoalkaloid content determined by titration with bromophenol blue was 12-30% greater than the sum of -chaconine and a-solanine determined by HPLC. The extraction-HPLC method was adapted to measure the glycoalkaloids in freeze-dried french fries (0.08-0.84 mg/100 g of product), skins (3.1-20.3 mg/100 g of product), potato chips (2.4-10.9 mg/100 g of product), and potato pancake powders (4.S-6.5 mg/100 g of product). The presence of the two glycoalkaloids in commercial foods was also confirmed by thin-layer chromatography. The possible significance of these findings to food safety and plant physiology is discussed.

Three anthocyanins were isolated from the acidified methanol extracts of UI 911 black beans (Phaseolus vulgaris L.) using solid phase extraction and preparative high-performance liquid chromatography . The anthocyanins were characterized using chromatographic and spectroscopic methods as delphinidin 3-glucoside (56%), petunidin 3-glucoside (26%), and malvidin 3-glucoside (18%). The monomeric anthocyanin content was 213 ± 2 mg/100 g of black beans (moisture content was 10.04 ± 0.02%). Keywords: Black beans; antioxidants; pigments; anthocyanins; electrospray ionization mass spectrometry

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Seven commonly used frying oils and fats (beef tallow, canola oil, partially hydrogenated canola oil, corn oil, cottonseed oil, soybean oil, and partially hydrogenated soybean oil) were heated at two different temperatures (190 and 204 °C) for 8 h/day until they reached a critical level of polar constituents. Iodine value, color index, and the levels of polar compounds and of dimeric and polymeric triglycerides were monitored daily using AOCS official methods. In general, oils with higher levels of unsaturated fatty acids produced more polar compounds compared to the more saturated oils. Cottonseed oil had the fastest rate of formation of polar material and of polymeric triglycerides of oils heated at 204 °C while corn oil had the greatest yield of polar material and polymeric triglycerides at 190 °C. For all seven oils and fats, total polar material was highly (r ≥ 0.99) and significantly (P < 0.001) correlated with the dimeric and polymeric triglyceride content and also highly (r > 0.94 and r ≤ −0.97) and significantly (P < 0.001 for the majority of cases; P < 0.05 for the poorest correlation) with the color index and iodine value, respectively. Despite its significant correlations with total polar material, color index was not a reliable indicator of oil quality. Keywords: Frying oils; total polar material; polymeric triglycerides; iodine value; oil quality