The proximate composition and nutritional content of oysters define their quality and commercial value. Cultivation site and harvest date may impact these characteristics. We assessed moisture, ash, protein, fat, and glycogen concentrations, mineral and free amino acid content, and free fatty acid composition in oysters Crassostrea gigas from three coastal regions of the Seto Inland Sea, Hiroshima, Okayama, and Hyogo, collected throughout the 2013–2014 harvest in Japan. The protein, fat, and ash content of oysters harvested during the same month was similar in all three regions. Moisture content decreased throughout the season, whereas glycogen content increased significantly during the same period and oysters from Okayama and Hyogo regions during March contained glycogen significantly higher than those from Hiroshima. Oysters cultured in Hiroshima had the highest zinc levels during December, January, February, and April. The abundant fatty acids in the oysters cultivated in these areas were eicosapentaenoic acid (EPA) and palmitic acid, and EPA was increased in oysters of Okayama and Hiroshima from November to April. Based on our data, we propose that oyster bed location and harvest date significantly impact the proximate composition and nutrients of oysters.

中文翻译：

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濑户内海长牡蛎主要成分的季节变化

牡蛎的大致成分和营养成分决定了它们的质量和商业价值。栽培地点和收获日期可能会影响这些特征。我们评估了来自濑户内海、广岛、冈山和兵库三个沿海地区的牡蛎的水分、灰分、蛋白质、脂肪和糖原浓度、矿物质和游离氨基酸含量以及游离脂肪酸组成2013-2014 年在日本收获。三个地区同月收获的牡蛎的蛋白质、脂肪和灰分含量相似。水分含量在整个季节下降，而糖原含量在同一时期显着增加，3 月份冈山和兵库地区的牡蛎所含的糖原显着高于广岛的。在广岛养殖的牡蛎在 12 月、1 月、2 月和 4 月的锌含量最高。这些地区养殖的牡蛎中富含的脂肪酸为二十碳五烯酸（EPA）和棕榈酸，11月至4月冈山和广岛的牡蛎中​​EPA含量增加。根据我们的数据，我们认为牡蛎床的位置和收获日期会显着影响牡蛎的大致成分和营养成分。