Antioxidant and cytotoxic properties of protein hydrolysates obtained from enzymatic hydrolysis of Klunzinger's mullet (Liza klunzingeri) muscle

Today, consumers are looking for functional foods that promote health and prevent certain diseases in addition to provide nutritional requirements. This study aimed to evaluate the antioxidant and cytotoxic properties of Liza klunzingeri protein hydrolysates. Fish protein hydrolysates (FPHs) were prepared from L. klunzingeri muscle using enzymatic hydrolysis with papain at enzyme/substrate ratios of 1:25 and 1:50 for 45, 90 and 180 min. The antioxidant activities of the FPHs were investigated through five antioxidant assays. The cytotoxic effects on 4T1 carcinoma cell line were also evaluated. The amino acid composition and molecular weight distribution of the hydrolysate with the highest antioxidant activity were determined by HPLC. All six FPHs exhibited good scavenging activity on ABTS (IC50=0.60-0.12 mg/mL), DPPH (IC50= 3.18-2.08 mg/mL), and hydroxyl (IC50=4.13-2.07 mg/mL) radicals. They also showed moderate Fe+2 chelating capacity (IC50=2.12-12.60 mg/mL) and relatively poor ferric reducing activity (absorbance at 70 nm= 0.01-0.15, 5 mg/mL). In addition, all hydrolysates showed cytotoxic activities against the 4T1 cells (IC50=1.62-2.61 mg/mL). 94.6% of peptide in hydrolysate with the highest antioxidant activity had molecular weight less than 1,000 Da. L. klunzingeri protein hydrolysates show significant antioxidant and anticancer activities in vitro and are suggested to be used in animal studies.

Influence of frying oil type and chill storage on the nutritional quality of farmed great sturgeon (Huso huso) / Influência do tipo de óleo de fritura e armazenamento a frio na qualidade nutricional do esturjão branco (Huso huso) de cativeiro

OBJECTIVE: The objective of this study was to investigate the effect of frying oils (canola, hydrogenated sunflower and soybean oils) available commercially and chill storage on the proximate and fatty acid composition of fried slices of farmed great sturgeon (Huso huso). METHODS: Slices of farmed great sturgeon were fried for four minutes at 160ºC in a deep-fryer using different frying oils (canola, hydrogenated sunflower and soybean oils). The oil-to-slice ratio was 2:1. After frying, the slices were allowed to be air cooled for two minutes prior to analysis. For performing the analysis, each of the abovementioned batches was divided into two groups: one group was analysed immediately after frying and the second group was chill-stored at 4ºC for three days and then analysed. RESULTS: After frying, the moisture content decreased while that of fat increased. Fatty acid composition of the slices is affected by type of frying oil. Frying increased the omega-6-to-omega-3 (n-6:n-3) fatty acid ratio while decreased Eicosapentaenoic Acid (C20:5 n-3) and Docosahexaenoic Acid (C22:6 n-3) contents. Proximate and fatty acid composition of raw slices did not change after chill storage. However, in fried- and chill-stored slices, Eicosapentaenoic Acid and Docosahexaenoic Acid contents decreased, while linoleic acid content increased. CONCLUSION: The fatty acid composition of the fried slices tended to resemble that of the frying oils, indicating fatty-acid equilibrium between oils and slices and, during chill storage, it is influenced by the type of frying oil. Slices fried with canola oil had omega-6-to-omega-3 ratios in the ranges recommended for human health.

OBJETIVO: O objetivo deste estudo foi investigar o efeito de óleos de fritura (canola, girassol hidrogenado e soja) disponíveis comercialmente e do armazenamento a frio em postas fritas de beluga (Huso huso), e na composição centesimal e lipídica. MÉTODOS: Postas de beluga de cativeiro foram fritas por imersão durante quatro minutos a 160ºC utilizando-se óleos de fritura diferentes (canola, girassol hidrogenado e soja). A razão entre óleo e postas foi de 2:1. Após a fritura, permitiu-se que as postas esfriassem a temperatura ambiente por dois minutos antes da análise. Para a análise, cada um dos grupos acima foi dividido em dois subgrupos: um subgrupo foi analisado imediatamente após a fritura e o segundo subgrupo foi armazenado resfriado a uma temperatura de 4ºC por três dias e então analisado. RESULTADOS: Após a fritura, o conteúdo da umidade diminuiu enquanto que da gordura aumentou. A composição dos ácidos graxos das postas foi afetada pelo tipo de óleo utilizado na fritura. A fritura aumentou a razão omega-6 para omega-3 e diminuiu os conteúdos dos Ácidos Eicosapentaenoico (C20:5 n-3) e Docosahexaenoico (C22:6 n-3). As composições centesimal e lipídica das postas cruas não se alteraram após o armazenamento a frio. Porém, os conteúdos de Ácidos Eicosapentaenoico e Docosahexaenoico nas postas fritas e resfriadas diminuíram, enquanto que de ácido linoleico aumentou. CONCLUSÃO: A composição lipídica das postas fritas tendeu à semelhança do óleo utilizado para a fritura, indicando um equilíbrio de ácidos graxos entre os óleos e as postas. A composição lipídica das postas durante o armazenamento a frio é influenciada pelo tipo de óleo de fritura. Postas fritas com óleo de canola continham uma razão de ômega-6 para ômega-3 dentro do intervalo recomendado para a saúde humana.