HZ University of Applied Sciences, P.O. Box 364, 4380 AJ Vlissingen, The Netherlands; Wageningen University, Department of Agrotechnology and Food Sciences, Food Quality and Design, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
Instituto de Investigaciones Marinas del CSIC, Eduardo Cabello 6, E-36208 Vigo, Spain.
Food Res Int. 2017 Oct;100(Pt 1):151-160. doi: 10.1016/j.foodres.2017.06.041. Epub 2017 Jun 20.
Oyster refinement, a common practice in France, is aimed at increasing the weight of oyster tissue and influencing the taste properties of the refined oysters. Refinement usually takes place in land-based systems where the oysters are fed with relatively high concentrations of microalgae. In this study the impact of feeding Skeletonema costatum and Rhodomonas baltica on the biochemical composition and sensory characteristics of Pacific cupped oysters (Crassostrea gigas) from the Eastern Scheldt during land-based refinement was studied. After a feeding period of four and seven weeks market-sized oysters were sampled for the analysis of fatty acids, free amino acids and volatile organic compounds and for a sensory evaluation by consumers and an expert panel. The algae Skeletonema costatum showed a lower ∑PUFA, ∑n-3, ∑n-6, C18:2n6, C18:3n3, C18:4n3, C22:6n3 content as compared with Rhodomonas baltica. These differences were also reflected in the fatty acid profile of the oysters fed with the corresponding algae diets. Furthermore, general linear model and principal component analysis showed marked differences in free amino acids and volatile organic compound content between Skeletonema, Rhodomonas fed oysters and reference oysters. For example, threonine, glutamine, leucine, histidine, (E)-2-hexenal, (E)-2octenal, (E)-2-octen-1-ol, (E,E)-2,4-octadien-1-ol, (E,Z)-3,6-nonadien-1-ol and (Z,E)-2,6-nonadienal contents were higher in Skeletonema fed oysters compared to Rhodomonas fed oysters. Sensory differences between the experimental oyster groups were shown. Skeletonema fed Pacific cupped oysters were characterized by a stronger seaweed flavor, higher perceived sweetness and a firmer texture in comparison with Rhodomonas fed oysters. Naïve consumers were only able to differentiate between Rhodomonas fed oysters and reference oysters.
牡蛎的精炼在法国是一种常见的做法，目的是增加牡蛎组织的重量并影响精炼牡蛎的口感特性。精炼通常在陆基系统中进行，在该系统中，牡蛎以相对较高浓度的微藻为食。在这项研究中，研究了在陆基精炼过程中投喂 Skele tonema costatum 和 Rhodomonas baltica 对来自东斯海尔德的太平洋杯形牡蛎（Crassostrea gigas）的生化组成和感官特性的影响。经过四周和七周的投喂期后，从市场上采集了大小合适的牡蛎进行脂肪酸、游离氨基酸和挥发性有机化合物的分析，并由消费者和专家小组进行感官评价。与 Rhodomonas baltica 相比，藻类 Skele tonema costatum 的∑PUFA、∑n-3、∑n-6、C18:2n6、C18:3n3、C18:4n3、C22:6n3 含量较低。这些差异也反映在投喂相应藻类饲料的牡蛎的脂肪酸谱中。此外，一般线性模型和主成分分析表明，Skele tonema、Rhodomonas 投喂牡蛎与参考牡蛎之间的游离氨基酸和挥发性有机化合物含量存在明显差异。例如，苏氨酸、谷氨酰胺、亮氨酸、组氨酸、（E）-2-己烯醛、（E）-2-辛烯醛、（E）-2-辛烯-1-醇、（E，E）-2,4-辛二烯-1-醇、（E，Z）-3,6-壬二烯-1-醇和（Z，E）-2,6-壬二烯醛的含量在投喂 Skele tonema 的牡蛎中较高，而在投喂 Rhodomonas 的牡蛎中较低。实验牡蛎组之间表现出感官差异。与投喂 Rhodomonas 的牡蛎相比，投喂 Skele tonema 的太平洋杯形牡蛎具有更强的海藻味、更高的感知甜度和更坚实的质地。未受过训练的消费者只能区分投喂 Rhodomonas 的牡蛎和参考牡蛎。
