Inhibition of Melanosis in Whiteleg Shrimp (Litopenaeus vannamei) during Refrigerated Storage Using Extracts of Different Avocado (Persea americana Mill.) By-Products

Abstract

Melanosis in shrimp usually leads to reduction in its shelf life and quality, which causes a significant loss in economic value of shrimp products. This study reports potential applications of nine ethanolic extracts of by-products, i.e., peel and/or seed from three Vietnamese avocado varieties as effective inhibitors of melanosis in whiteleg shrimp. Six out of nine shrimp samples treated with the prepared extracts (0.025%, w/v) reduced melanosis and lipid oxidation more significantly as compared to those treated with sodium metabisulfite (SMS, 1.25%, w/v) and control groups (treated with water) during 8-day storage at 4 o C (P<0.05). These six extracts had mean gray values ranging from 47.0±0.7 to 57.3± 0.4% were lower than those treated with SMS (mean gray of 39.8±0.4%). The inhibition of melanosis and lipid oxidation in shrimp for these extracts could be attributed to their high content of polyphenols [total phenolic content (TPC) from 44.5±1.1 to 144.7±1.9 mg gallic acid equivalents/g dried weight] and strong antioxidant activities [including 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP), and tyrosinase enzyme inhibition]. Pearson statistical analysis showed strong correlation for melanosis inhibition to TPC and DPPH scavenging (r> 0.80) followed by tyrosinase inhibition and FRAP (r>0.50). The findings obtained from this study suggest potential utilization of avocado by-product extracts as safe and cheap natural alternatives to traditional sulfites for anti-melanosis and shelf life extension of whiteleg shrimp.

Astaxanthin Complex as an Antioxidant in Preventing Prawn Blackening or Melanosis

“…Treatment regarded as "natural" is often seen by consumers as more desirable than any "chemical" treatment nowadays. Therefore, various studies have been investigated to prevent prawn melanosis using natural compounds such as commercial proteases ficin and papain [39], enokitake mushroom extract [15,40]; grape seed extract [41]; moringa extract [42]; lemon and orange peel extracts [43,44]; lemon and pomelo peel extracts combined with copper sulphide nanoparticles [45]; green tea-and amla extracts [46]; plant polyphenols [47]; catechin [48,49]; Annona muricata leaves extract [50]; kojic acid [22,[51][52][53][54]; chitosan [55]; fully deacetylated chitosan coating incorporated with kojic acid and clove oil [56]; chamuang leaf extract [57]; avocado by-product extracts [58]; curry and moringa leaves extracts [59]; lead seed extract [60]; olive phenolic compounds extracted from olive oil by-product [61]; rosemary and green tea extracts [62]; edible brown algae extract [63]; mango seed kernel extract [64]; plant polyphenolic compounds [65] and so on.…”