2011 Annual Report
1a.Objectives (from AD-416)
(1) Establish which specialty crops respond best to UV-B treatment for the enhancement of their health-promoting properties (e.g. phenolics, antioxidants) and determine dose-response. (2) Establish the localized and distal effects of UV-B treatment on plant tissues (e.g. skin vs. interior). (3) Determine the effect of postharvest conditions on the synthesis of phenolic compounds with and without UV-B treatment and analyze the stability of these compounds during normal storage. Determine the effects of these treatments on sensory quality and nutritional value. (4) Verify enhanced bioavailability of phenolic compounds following UV-B treatment using in-vitro and in-vivo methods.
1b.Approach (from AD-416)
Recently harvested produce, including whole and precut fruits and vegetables such as whole grapes, whole berries, cherry tomatoes, baby carrots, broccoli florets, and apples will be exposed to UV-B treatments at different doses. Effectiveness of the treatments will be evaluated and subsequently optimized based on increased phenolic compound concentrations, antioxidant capacity, and PAL activity. Increases in specific compounds, such as trans-resveratrol, anthocyanins, quercetin glycosides, tocopherols, and carotenoids will be determined through HPLC analysis. The potential impact or improvement resulting from UV-treatment on quality factors (color, firmness, acidity/sweetness ratio, ascorbic acid, etc.), sensory attributes, respiration rate (under controlled atmosphere, temperature, and %RH) and shelf-life will also be evaluated for the most promising samples. Changes in the bioavailability of phenolic compounds from UV-B treated fruits and vegetables will be verified using both in-vitro and in-vivo methods.
AFRI funding supported studies on effects of UV on other specialty crops to enhance their nutritional value. Increased antioxidant levels in carrots were observed and various forms of carrots were compared in terms of these benefits. Further studies were recently begun to investigate sensory properties of treated carrots. Screening studies of a wide range of specialty crops indicated little enhancement in antioxidants in any specialty crop other than carrots.