Impact of ultraviolet radiation treatments on the physicochemical properties, antioxidants, enzyme activity and microbial load in freshly prepared hand pressed strawberry juice

Abstract

Freshly prepared, hand-pressed strawberry fruit juice was exposed to ultraviolet radiation (254 nm) at room temperature (25 ℃ ± 1 ℃) for 15, 30 and 60 min with 0 min serving as control. Results revealed decrease in pH, total soluble solids and titratable acidity, while colour parameters (L*, a* and b* values) and clarity of juice (% transmittance) increased significantly. All the results corresponded to exposure time to ultraviolet radiation. Bioactive compounds (total phenolics, ascorbic acid and anthocyanins) decreased along with a recorded reduction in polyphenol oxidase enzyme and 1,1-diphenyl-2-picryl hydrazyl radical scavenging activities, which were again dependent on exposure time. Results on the microbial studies showed significant reduction by 2-log cycles in aerobic plate count as well as in total yeast and mould counts. Though negative results were observed for certain parameters, this is the first time it was endeavoured to demonstrate the impact of ultraviolet radiation radiation on freshly prepared, hand-pressed strawberries juice.

Impact of Combination Treatments of Modified Atmosphere Packaging and Refrigeration on the Status of Antioxidants in Highly Perishable Strawberries

“…Polyphenolic compounds, a cluster of plant secondary metabolites (such as phenolic acid, tannin, flavonoids, flavonols), exhibit rich biological effects including those of anti-aging, anticancer, anti-inflammatory and antioxidant activities (Bhat et al 2011;Bhat and Stamminger 2014). In this study, control samples showed high levels of TPC (1,919 g/100 g GAE), supporting the notion that strawberries possess high antioxidant capacity.…”

“…In addition to these, usually, antioxidant activity, which is measured as percentage inhibition of DPPH radical, can be correlated with TPC (Gorinstein et al 2004;Bhat and Stamminger 2014). However, in this study, a positive correlation was recorded only in selected strawberry samples maintained at room temperature (25C) without MAP, 0C MAP, 5C (MAP and without MAP) and 10C MAP.…”

“…Evaluating the antioxidant activity in a given sample by DPPH• assay is considered to be one of the most reliable, sensitive and rapid methods (Sánchez-Moreno 2002; Bhat and Stamminger 2014;Shin et al 2014). In the present study, strawberry samples used as control (freeze-dried) showed higher inhibition of DPPH• radical (95.96%), and this can be attributed to the presence of elevated amounts of antioxidant compounds in strawberries (Hannum 2004;Bhat and Stamminger 2014).…”

“…However, owing to the smooth texture and elevated sensitivity to attack by molds, they are considered as one of the fastest perishable fruits (Blanda et al . ; Bhat and Stamminger , ). Strawberries are metabolically active after harvest and can rapidly deteriorate even in the absence of any spoilage microorganisms.…”

Red Fruits: Extraction of Antioxidants, Phenolic Content, and Radical Scavenging Determination: A Review

“…The addition of some substances, such as BTH (benzo-thiadiazole-7-carbothioic acid S-methylester) [37], or the radiation of the berries with different light treatments, like ultraviolet [38] or blue light [39] could enhance the amount of antioxidant compounds and antioxidant capacity.…”