Research on characteristics of raw oysters (Crassostrea gigas) collecting from two culturing areas in the North of Khanh Hoa province

Abstract

Pacific oysters are increasing market demand owing to their nutritional value. There are many areas in Khanh Hoa province cultivating these species but few results on the chemical composition have been published. This study aimed to evaluate the nutritional composition including moisture, total protein, ash, total fat, amino acids and minerals of Crassostrea gigas from Van Ninh (VN) and Ninh Hoa (NH) of Khanh Hoa province over 2 seasons (dry and rainy season). The results showed the size of oysters was dominated by 10 - 13 oysters/kg (N2), following by size of 14 - 16 oysters/kg (N3) and 8 - 10/kg (N1). The meat recovery rate decreased in the order N3 > N2 > N1 when sampling at the same time. The nutritional values of oyster meat harvested in the dry season was mostly higher than that in the rainy season. Protein was particularly the main nutritional component in meat, 12% ± 1.1 (dry season) and 7% ± 1.5 (rainy season) respectively and there was no significant difference (P >0.05) between NH and VN samples. Total lipid content did not significantly difference (P > 0.05) between samples taken in the two farming areas. The zinc and selen content of oysters from both NH and VN were quite high. Zinc was fluctuating ~90.6 mg/kg in oyster meat collected in the dry season and ~70 mg/kg in oyster meat collected in the rainy season. Selen was ~0.2 mg/kg and ~0.3 mg/kg in sample collected in rainy and dry season, recpectively. In addition, oysters were rich in essential amino acids and the amino acid composition was higher in the samples collected in dry season than in the rainy season. Glutamate was the dominant component in oyster meat collected in the rainy season (~ 0.55 g/100 g) and Cystine is the main component when analyzing samples in dry season (~1 g/100 g).