Evaluation of Green Tea Extract as a Glazing Material for Shrimp Frozen by Cryogenic Freezing

Abstract

Solutions of green tea (Camellia sinensis) extract (GTE) in distilled water were evaluated as a glazing material for shrimp frozen by cryogenic freezing. Total of 2%, 3%, and/or 5% GTE solutions (2GTE, 3GTE, 5GTE) were used for glazing. Distilled water glazed (GDW) and nonglazed shrimp (NG) served as controls. The GTE was characterized by measuring color, pH, (o) Brix, total phenols, and % antiradical activity. Individual catechins were identified by HPLC. The freezing time, freezing rate, and energy removal rate for freezing shrimp by cryogenic freezing process were estimated. The frozen shrimp samples were stored in a freezer at -21 °C for 180 d. Samples were analyzed for pH, moisture content, glazing yield, thaw yield, color, cutting force, and thiobarbituric acid reactive substances (TBARS) after 1, 30, 90, and 180 d. The HPLC analysis of GTE revealed the presence of catechins and their isomers and the total polyphenol content was 148.10 ± 2.49 g/L. The freezing time (min) and energy removal rate (J/s) were 48.67 ± 2.3 and 836.67 ± 78.95, respectively. Glazed samples had higher moisture content compared to NG shrimp after 180 d storage. GTE was effective in controlling the lipid oxidation in shrimp. Glazing with GTE affected a* and b* color values, but had no significant effect on the L* values of shrimp.

Comparison of the Cryoprotective Effects of Trehalose, Alginate, and Its Oligosaccharides on Peeled Shrimp (Litopenaeus Vannamei) During Frozen Storage

“…In addition, the freezing‐induced denaturation of shrimp proteins (Lopkulkiaert and others ) is caused by the formation of larger ice crystals during frozen storage. Subsequently, the decreases L* values might be attributed to the degradation of astaxanthin and lipid oxidation (Sundararajan and others ). Nevertheless, the inhibitory effect of treatment with 0.5% and 1.0% sodium pyrophosphate, trehalose, and alginate oligosaccharide on the changes in L* values were significant compared with water‐treated samples ( p < 0.05).…”

“…Significantly, the functional properties of the proteins (such as myofibrillar, sarcoplasmic, and connective tissue proteins) in shrimp affect the quality and deterioration of muscles during processing and storage. These proteins affect the quality of the shrimp directly, including factors, such as tenderness, water retention capacity, juiciness, and flavor (Sundararajan and others ). Frozen storage is the most common method for the long‐term preservation of shrimp products, which can inhibit microbial growth, slow enzymatic activity, and also preserve taste and nutritional value.…”

Cryoprotective Effects of Trehalose, Alginate, and its Oligosaccharide on Quality of Cooked-Shrimp (Litopenaeus vannamei) During Frozen Storage

“…Subsequently, the decreases L * values might be due to the degradation of astaxanthin and lipid oxidation (Sundararajan et al . ). Nevertheless, the inhibitory effects of treatment with 1.0% (w/v) Na 4 P 2 O 7 , trehalose, alginate, and alginate oligosaccharide on the changes in L * values were significantly greater than that of water‐treated samples ( P < 0.05).…”

Trout‐Skin Gelatin‐Based Edible Films Containing Phenolic Antioxidants: Effect on Physical Properties and Oxidative Stability of Cod‐Liver Oil Model Food

“…The significant drop ( P < 0.05) in activity of films with EGCG is possibly because EGCG is a cis ‐configured catechin and oxidizes following first‐order kinetics (Li and others 2011). Films with GTP retained activity most likely due to multiple antioxidants present in green tea including a mixture of cis ‐ and trans ‐configured catechins (Sundararajan and others 2011). Trans ‐configured catechins have a complex degradation mechanism often involving epimerization and degradation (Li and others 2011).…”