Penelope Perkins-Veazie

A rapid spectrophotometric method for analyzing lycopene content in tomato and tomato products

Abstract Lycopene is a carotenoid that has antioxidant properties and imparts the red pigment in some fruits and vegetables. Tomato ( Lycopersicon esculentum Mill.) is one of the predominant lycopene sources in a typical North American diet. Current methods to assay lycopene content in fruit are time consuming, expensive, and use hazardous organic solvents. Here, we report a method by which light absorbance measured with a scanning xenon flash colorimeter/spectrophotometer is used to quantify lycopene content in pureed translucent fruit samples. We evaluated 13 tomatoes (four different cultivars) and 38 tomato products. Our puree absorbance method (PAM) had linear correlation coefficients with lycopene content determined by hexane extraction/spectrophotometry of R 2 =0.97 for fresh tomato, and 0.88 for tomato products. These linear correlations between methods show that this rapid method will likely work for quantitating lycopene content in purees of fresh tomatoes and some prepared foods. Since pureeing is the only processing required and no chemicals are needed, the method is rapid, inexpensive and requires no hazardous chemicals. Since lycopene has health benefits and food colorant potential, lycopene content in fruits is of interest to the food industry. This simple method for measuring lycopene content in a wide variety of foods and food products promises widespread use for lycopene quantitation.

Effects of Deoxynivalenol on Content of Chloroplast Pigments in Barley Leaf Tissues

To understand further the role of deoxynivalenol (DON) in development of Fusarium head blight (FHB), we investigated effects of the toxin on uninfected barley tissues. Leaf segments, 1 to 1.2 cm long, partially stripped of epidermis were floated with exposed mesophyll in contact with DON solutions. In initial experiments with the leaf segments incubated in light, DON at 30 to 90 ppm turned portions of stripped tissues white after 48 to 96 h. The bleaching effect was greatly enhanced by addition of 1 to 10 mM Ca(2+), so that DON at 10 to 30 ppm turned virtually all stripped tissues white within 48 h. Content of chlorophylls a and b and of total carotenoid pigment was reduced. Loss of electrolytes and uptake of Evans blue indicated that DON had a toxic effect, damaging plasmalemmas in treated tissues before chloroplasts began to lose pigment. When incubated in the dark, leaf segments also lost electrolytes, indicating DON was toxic although the tissues remained green. Thus, loss of chlorophyll in light was due to photobleaching and was a secondary effect of DON, not required for toxicity. In contrast to bleaching effects, some DON treatments that were not toxic kept tissues green without bleaching or other signs of injury, indicating senescence was delayed compared with slow yellowing of untreated leaf segments. Cycloheximide, which like DON, inhibits protein synthesis, also bleached some tissues and delayed senescence of others. Thus, the effects of DON probably relate to its ability to inhibit protein synthesis. With respect to FHB, the results suggest DON may have multiple roles in host cells of infected head tissues, including delayed senescence in early stages of infection and contributing to bleaching and death of cells in later stages.

Impact of cultivar and production practices on yield and phytonutrient content of organically grown watermelon

Abstract Cultural practices can affect quality and phytonutrient content of watermelon [Citrullus lanatus var. lanatus (Thunb.) Matsum. & Nakai]. Knowing which cultivars perform well under various production systems, and how these systems affect quality, yield, and phytonutrient content is imperative to ensure high quality and yield. There is limited information on how watermelon cultivars perform when grown with organic practices. Production characteristics of six watermelon cultivars from certified organic seed sources were compared under high (black plastic and mechanical cultivation for weed control) and low input (no-till) organic culture. The high input production method almost doubled the number of fruit produced for all cultivars; producing greater yields and heavier average fruit weights, but fruit had decreased quality (lower Brix and lycopene content) compared with the low-input production. ‘Triple Star’ was the most productive seedless cultivar in terms of number of fruit in both organic fields and had the highest marketable yield in the low-input field. ‘Early Moonbeam’ produced the largest number of fruit and the smallest fruit of the seeded cultivars. ‘Allsweet’, a seeded cultivar, had the highest marketable yield due to its larger size. ‘Triple Star’ had the highest quality (high lycopene and Brix content) in the low input field, but all triploid cultivars had similar quality aspects in the high input field. Among seeded cultivars, ‘Allsweet’ had the best quality at both locations; however, average lycopene content/fruit under low-input production was not significantly different when compared with ‘Sugar Baby’.