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United States Department of Agriculture

Agricultural Research Service

Research Project: New Sustainable Processing Technologies to Produce Healthy, Value-Added Foods from Specialty Crops and their Co-Products

Location: Healthy Processed Foods Research

Title: Antioxidant characterization and sensory evaluation during storage of ultraviolet-B light exposed baby carrots (abstract)

Authors
item Du, Wen-Xian
item Breksa, Andrew
item Avena Bustillos, Roberto
item McHugh, Tara

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 12, 2013
Publication Date: N/A

Technical Abstract: Baby carrot processing induces wounding stress activation of phenylalanine ammonia-lyase (PAL), enhancing its nutrient content by increasing synthesis of secondary metabolites. Ultraviolet-B (UV-B) exposure further promotes the formation of soluble phenolic compounds, significantly increasing antioxidant content. This study evaluated the effect of UV-B exposure on storage stability and sensory characteristics of baby carrots. Baby carrots were exposed to UV-B energy dose of 60 mJ/cm2 with bimodal peak irradiance of 20 mW/cm2. After incubation at 10°C for 72 h to allow enzyme activation, carrots were stored at 2°C for 18 days, evaluating responses at five storage periods in terms of chlorogenic (CA), caffeic, coumaric, ferulic,and ascorbic acids, total soluble phenolics (TSP), antioxidant capacity (AC), PAL activity, quality and sensory attributes. CA was the predominant phenolic compound. UV-B treated samples exhibited a rapid CA increase until day 7 and then, modest increase. Final CA concentration in treated samples was approximately 3-fold higher than control. Caffeic acid followed similar trend, but at much lower concentrations, with a plateau reached by day 14. Final caffeic acid in treated samples was only 2-fold higher than control. Ferulic acid increased in both samples, being higher in UV-B treated samples. Coumaric acid was not detected in control samples. Coumaric acid was also undetectable in treated samples at day 0, but rapidly increased by day 3. By day 7, it had decreased significantly, and continued decreasing during storage.TSP and AC increased 1.7-fold in UV-B treated samples after storage, as result of increased PAL activity. There were no changes in ascorbic acid, pH, °Brix, color, hardness, or sensory preference determined by flavor, texture, appearance and acceptability comparisons between control and treated samples. UV-B light exposure, as an additional processing step, enhances the antioxidant content of baby carrots. This enhancement persists over extended storage, without affecting quality and acceptability.

Last Modified: 8/27/2014
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