Optimization of the processing conditions for producing osmo-dehydrated arazá (Eugenia stipitata, McVaugh) and evaluation of its antioxidant content and activity

BACKGROUND: Arazá, a tropical berry rich in thermolabile antioxidants (ascorbic-acid/phenolics/flavonoids/carotenoids), is a potential ingredient for preparing functional foods; however, its high perishability hinders its industrial application. Osmotic-dehydration (OD), a processing method that operates at low temperature ranges, may be adequate for improving arazá's shelf-life without reducing its palatability/nutritional quality. Physicochemical and nutritional properties depend on the time/temperature/osmotic-solution concentration applied; therefore, parameters optimization is required. Processing selection must also consider treatment effect on antioxidants composition/activity/bioaccessibility in the gastro-intestinal (GI) tract, key factors in bioactives health benefits. OBJECTIVES: a) Optimize OD duration/temperature/sucrose concentration to maximize process efficiency/total-polyphenol content/overall-acceptability using principal component analysis and Response-Surface-Methodology/Desirability-Function b) Determine OD effect on antioxidant content/activity/bioaccessibilities before and after gastro-intestinal digestion. RESULTS AND CONCLUSIONS: Processing conditions have opposite effects on sensory and chemical properties; reaching antioxidant content/activity highest levels in the osmo-dehydrated fruit required 60 min/20°Bx; whereas, the best organoleptic scores demanded 180 min/60°Bx. Although osmotic-drying reduced the fruit's antioxidant content/activity 39–76%, the process improved antioxidants bioaccessibilities, since these values were: 63–85% (untreated fruit) and 72–90% (osmodehydrated arazá (ODA)), whereas the activity retention levels were 67–76% (untreated fruit/ODA).