Growth,nutritional quality and safety of oysters (Crassostrea gigas) cultured in the lagoon of Venice (Italy)

Quality aspects of oysters (Crassostrea gigas) from a suspended culture in the lagoon of Venice (Valle Dogà) were examined in different seasons over a 1‐year period. Ecophysiological and commercial quality indicators (condition index, content of meat, shell and intervalvar fluid), nutritional quality parameters (proximate and mineral composition, glycogen content, fatty acid profile, cholesterol, plant sterols, fat‐soluble vitamins content) and levels of organic pollutants (polychlorinated biphenyls and organochlorine pesticides) were determined at different times of the year. Seasonal variations were observed in the nutrient content, with particular regard to moisture (ranging from 866.8 g kg^?1 in June to 938.8 g kg^?1 in September), protein (23.9 g kg^?1 in September to 76.6 g kg^?1 in June), ash (22.5 g kg^?1 in February to 29.5 g kg^?1 in July), lipid (3.0 g kg^?1 in September to 8.8 g kg^?1 in June) and glycogen (0.7 g kg^?1 in September to 11.5 g kg^?1 in February). In spite of this variability, the nutritional quality of the oysters was generally good, especially just before gamete release when the concentration of nutrients was at its maximum. Low levels of organochlorine chemicals were detected in the edible meat of oysters but, because only a limited number of samples were analysed, no general conclusion can be drawn on the safety of seafood from this area. Copyright © 2004 Society of Chemical Industry     

阿特拉津在太平洋牡蛎体内的蓄积、分布与消除

采用半静态水质接触染毒法,将太平洋牡蛎分别暴露在阿特拉津质量浓度为10μg/L和100μg/L的海水中,研究阿特拉津在太平洋牡蛎体内的蓄积特征、组织分布和消除规律。结果表明,不同暴露质量浓度下,各组织中阿特拉津含量在3～7 d达到平衡,半衰期为0.20～0.32 d,生物富集系数为1.68～3.46 mL/g,鳃和内脏团是太平洋牡蛎的主要蓄积靶组织,而闭壳肌中阿特拉津含量最低。太平洋牡蛎对阿特拉津的消除能力随暴露质量浓度的增大而增强,各组织中阿特拉津的含量随净化时间呈指数下降,净化1 d后的消除率为90.1%～97.1%,其主要代谢途径推测为鳃的作用。     

植物基人造肉产品购买意愿及影响因素——基于武汉市消费者的实证分析

为深入了解植物基人造肉市场快速发展背景下国内消费者对人造肉产品购买的意愿及影响因素,以武汉市202位消费者调研数据为样本,构建了消费者人造肉食品购买意愿研究模型.研究发现,消费者的感知体验和感知信任对购买意愿的影响显著,但感知有用性并未对消费者购买意愿产生显著影响.价格制定、技术风险和口感风味等因素通过影响消费者感知特...     

姜汁对太平洋牡蛎（Crassostrea gigas）酶解液风味改善的研究

通过感官评价、顶空固相微萃取与气相色谱-质谱联用技术（solid phase micro-extraction gas chromatographmassspectrometer,SPME-GC/MS）以及计算相对气味活度值（ralative odour active value,ROAV）的方法分析太平洋牡蛎（Crassostrea gigas）酶解前后挥发性成分的变化情况,探讨姜汁对牡蛎脂质氧化的抑制作用和改善牡蛎酶解产物风味的效果。结果表明：与新鲜牡蛎相比,酶解液中脂质氧化产物,如异戊醛、壬醛、2-壬烯醛和3,5-辛二烯酮含量分别增加至5.09%、1.6%、1.3%、0.5%,使牡蛎酶解液呈现出较重的腥味与哈喇味,说明牡蛎风味的劣变与酶解过程中发生的脂质氧化有关。牡蛎酶解过程中添加姜汁,脂肪氧化产生的不愉快成分如（E）-2-戊烯醛、（Z）-4-庚烯醛、壬醛、2,3-辛二酮等未被检测到;异戊醛、己醛、（E）-2-己烯醛等物质的相对含量分别减少了81.02%、33.28%、54.39%。姜汁中挥发性成分如香叶醇、香茅醇、对伞花烃和芳樟醇等成为其新的主体呈味成分,并贡献出花香、柠檬香等愉快气味。因此,姜汁对改善牡蛎酶解液的风味有显著效果。     

复合酶水解牡蛎蛋白的动力学研究

对太平洋牡蛎蛋白进行复合酶(风味蛋白酶、胰蛋白酶的酶活力比为2.3:1)水解特性研究,探讨了底物浓度和酶浓度对水解度(DH)的影响。建立了复合酶水解牡蛎蛋白的动力学模型,确定了模型常数,并分析了多肽的平均链长、相对分子质量与酶解时间的关系。验证实验证实模型预测结果与实际测得的结果一致,表明该动力学模型具有一定的实用价值。     

Reductions of Vibrio parahaemolyticus in Pacific oysters (Crassostrea gigas) by depuration at various temperatures

Consumption of raw oysters has been linked to several outbreaks of Vibrio parahaemolyticus infection in the United States. This study investigated effects of ice storage and UV-sterilized seawater depuration at various temperatures on reducing V. parahaemolyticus in oysters. Raw Pacific oysters (Crassostrea gigas) were inoculated with a mixed culture of five clinical strains of V. parahaemolyticus (10290, 10292, 10293, BE 98-2029 and 027-1c1) at levels of 10⁴⁻⁶ MPN/g. Inoculated oysters were either stored in ice or depurated in recirculating artificial seawater at 2, 3, 7, 10, 12.5, and 15 °C for 4–6 days. Holding oysters in ice or depuration of oysters in recirculating seawater at 2 or 3 °C for 4 days did not result in significant reductions (P > 0.05) of V. parahaemolyticus in the oysters. However, depuration at temperatures between 7 and 15 °C reduced V. parahaemolyticus populations in oysters by >3.0 log MPN/g after 5 days with no loss of oysters. Depuration at refrigerated temperatures (7–15 °C) can be applied as a post-harvest treatment for reducing V. parahaemolyticus in Pacific oysters.     

Seasonal variation in the chemical composition and fatty acid profile of Pacific oysters (Crassostrea gigas)

The chemical composition and fatty acid profile of the tray-cultured Pacific oyster (Crassostrea gigas) were measured and compared over a 13 month period. Oysters (120–150 g) were cultured in Cork Harbour and samples taken for analysis at monthly intervals. The moisture, fat, protein, glycogen and ash contents of the flesh were analysed. The fatty acid profile of the flesh was analysed by gas chromatography. The condition indices of the oysters were determined. The chemical composition of the oysters grown in Cork Harbour was similar to literature values for the same species grown in Pacific waters. Ranges for the chemical composition (dry flesh weight basis) were: fat (7.8–8.7%), protein (39.1–53.1%), glycogen (21.6–38.9%) and ash (4.0–12.1%).     

云南省影响消费者购买猪肉、大米和西红柿的因素分析

选取影响消费者购买猪肉、大米和西红柿的四个因素(包装、销售地点、产品认证和品牌),每个因素设2或3的水平,采用联合分析法进行评价。结果显示:产品的包装、销售地点、产品认证、品牌四个因素中对消费者购买大米、猪肉和西红柿起主要作用的是销售地点,尤其是超市的作用十分明显,流动商贩在云南省仍然有一定的市场需求。      

Combined effect of ozonated water and chitosan on the shelf-life of Pacific oyster (Crassostrea gigas)

Effects of ozonated water and chitosan treatment on the shelf-life extension of Pacific oysters (Crassostrea gigas) stored at 5 ± 1 °C were studied. Results indicated that ozonated water treatment reduced the total microbial load of fresh oysters by about 10-fold (from 3.2 × 10³ CFU/g to 1.8 × 10² CFU/g) before storage and the microbial flora was different with that of raw samples. The wide-spectrum antibacterial property of chitosan against bacteria isolated from oysters was confirmed, and chitosan concentration of 5.0 g/l was eventually determined for application in oyster preservation. Based on microbiological analysis, biochemical indices determination and sensory evaluation, shelf-lives of 8–9 days for control, 10–12 days for ozonated water treated samples, 14–15 days for chitosan treated samples and 20–21 days for samples with combined treatment were observed, indicating that ozonated water and chitosan have a great potential for oyster preservation.Industrial relevanceAs seafood, Pacific oysters have a short shelf-life. Improvements in the shelf-life of oysters can have an important economic impact by reducing losses and by allowing the products to reach distant and new markets.In this work, Shelf-life of oysters with combined treatment of ozonated water and chitosan doubled, which has great practical meaning, and the process could be fully adopted by the food industry.We also did some research about the changes in microbial flora after ozonated water treatment. This work could help in preservation of oysters when ozone or ozonated water concerned.We discovered Wide-spectrum antibacterial property of chitosan against the strains isolated from raw oysters. The potential for using chitosan as a natural preservative in oysters was approved.     

The effects of carrier,benefit, and perceived trust in information channel on functional food purchase intention among Chinese consumers

The importance of consumers’ perceptions and adoption behavior has been recognized in the development of functional food innovation, but the issues have not been widely explored in China. This study aimed to examine the effects of carrier, benefit, and trust in information channel about functional foods on purchase intention as well as the demographic differences of these effects. A survey with 1144 respondents from Mainland China revealed that carriers were more important factors than benefits for perceived attractiveness and purchase intention. Benefits were more positively evaluated when attached to a more attractive carrier. Benefits of improving the body’s natural defense system were most favored by all groups; benefits about specific diseases were suitable to tailor for certain groups. Consumers with low educational level were reluctant to functional foods. The improvement of consumer education level does not necessarily increase the consumers’ purchase intention. Given the Chinese acquaintance society and the jeopardized public trust in food safety, the interpersonal channel was the most trusted information channel. However, perceived trust in mass media had more remarkable effects in predicting purchase intention toward functional foods, the typical products with credence attributes. Trust in mass media negatively interacted with friends’ recommendation in affecting purchase intention. These findings extend our understanding of how to tailor products for different groups and the effects of information channels on purchase intention.     

Influence of packaging strategy on microbiological and biochemical changes in high‐pressure‐treated oysters (Crassostrea gigas)

BACKGROUND: High‐pressure (HP) treatment is being increasingly employed for commercial processing of oysters, but there is relatively limited information on the microbiological quality and enzymatic activity of HP‐treated in‐shell oysters. The objective of this research was to study the influence of packaging strategy on microbiological and biochemical changes in oysters HP treated at 260 MPa for 3 min or 400 MPa for 5 min at 20 °C and stored at 0 °C either aerobically on ice, in vacuum packaging (VP) or under modified atmosphere packaging (MAP; 40% CO₂, 60% N₂), compared with changes in untreated oysters. RESULTS: Both HP treatments reduced the microbiological load to below the detection limit (<100 colony‐forming units g^?1). MAP and VP also delayed subsequent microbial growth compared with aerobically stored samples. After 21 days of storage, total volatile base levels remained lower than the proposed acceptability limits for all samples; however, after 28 days, only oysters HP treated at 400 MPa, irrespective of the packaging system used, did not exceed this limit. HP increased the thiobarbituric acid‐reactive substance (TBARS) values of oysters, indicating increased lipid oxidation. During storage, TBARS values of all MAP and VP oysters remained lower than those of aerobically stored oysters. CONCLUSION: HP treatment, in combination with adequate chilled storage and MAP, can extend the shelf‐life and safety of oysters. Copyright © 2008 Society of Chemical Industry     

Accumulation of paralytic shellfish poison (PSP) and biotransformation of its components in oysters, Crassostrea gigas, fed with the toxic dinoflagellate Alexandrium tamarense

As a part of our studies on the mechanism of uptake of paralytic shellfish poison (PSP) and the kinetics of its accumulation in bivalves, oysters Crassostrea gigas were experimentally contaminated with PSP by being fed with the toxic dinoflagellate Alexandrium tamarense for 2, 4, 6, 8 and 10 days. Temporal variations in the PSP contents and their profiles in oysters during the feeding experiment were monitored by high-performance liquid chromatography (HPLC) and the toxin profile of the oysters was compared with that of A. tamarense. Toxins excreted from the infested oysters into the seawater for 2 and 10 days were recovered and analyzed by HPLC. PSP toxicity rapidly appeared in the tissues of oysters and their toxicity levels reached 0.6 (0.3), 2.2 (1.1), 1.0 (0.5), 3.4 (1.6) and 1.1 (0.5) MU/g (nmol/g) shucked meat at 2, 4, 6, 8 and 10 days, respectively. The accumulation rates of toxin, calculated from the total amount (nmol) of toxins expressed by the total cell number fed during the exposure period and the toxicity of the oysters, were 14.1, 18.7, 5.1, 14.9 and 3.2% for 2, 4, 6, 8 and 10 days. During feeding experiments, the toxin profile of oysters changed substantially, showing marked differences from the proportions found in the toxigenic dinoflagellate used as food. The toxin components in this strain existed almost exclusively as beta-epimers, which accounted for 66.3 mol% of the total. This contrasts with the case of the oysters, where the beta-epimers represented 24.8, 29.8, 25.1, 27.3 and 25.2 mol% of the total at 2, 4, 6, 8 and 10 days, respectively. The amount of gonyautoxin-1 (GTX1) accumulated in oysters increased linearly and slowly for 8 days and the maximum content of GTX1 reached 51.3 mol%. The composition of GTX group compounds recovered from the seawater in which the oysters had been reared was a little different from that within the oyster tissues.     

中华绒螯蟹鲜活及死后品质变化规律初探

为了探究中华绒螯蟹新鲜、垂死及死亡初期品质变化规律,选取鲜活、垂死、死后0、2、5、10、15和24 h共8个状态下的中华绒螯蟹进行研究,对此八种状态下的中华绒螯蟹进行感官评价,并测定失重率以及可食部位得率,结合滋味指标游离氨基酸(FAA)、非蛋白氮(NPN)、鲜度指标K值、p H、腐败指标挥发性盐基氮(TVBN)、生物胺进行品质研究。结果表明:中华绒螯蟹的感官评分随死后时间的延长而下降,中华绒螯蟹在死后10 h出现明显的腐败臭味,死后24 h打开蟹壳,里面的气味达到可接受极限;新鲜和垂死两个状态下,蟹的品质指标几乎无显著性差异(p<0.05);中华绒螯蟹在死亡10 h检测出生物胺,且直到15 h其体内有毒生物胺的含量较低,不足以引起中毒。多数指标均在D5和D10时发生较大改变,表明此时中华绒螯蟹品质有较大变化,中华绒螯蟹在死后10 h进入腐败阶段。      

Consumer perception,health information,and instrumental parameters of cupuassu (Theobroma grandiflorum) goat milk yogurts

Although the demand for goat milk products has been growing, they have lower consumer acceptability than products derived from cow milk. However, the addition of cupuassu pulp can be used to improve the formulation of these products. For this reason, the aim of this study was to investigate the influence of new goat milk yogurt manufactured with cupuassu pulp on physicochemical properties, consumers’ perceptions, and overall consumer acceptance. In addition, the effect of antioxidant health information on consumer acceptance and purchase intention of cupuassu goat milk yogurts was evaluated. The results demonstrated a positive expectation regarding linking and familiarity to goat milk products and products with cupuassu pulp. The pH, total phenolic content, lightness, redness, yellowness, and apparent viscosity were potentially affected by the addition of cupuassu, with the highest concentration of cupuassu (10%) exhibiting the greatest changes in parameters. Based on principal component analysis, partial least squares regression, and just-about-right and penalty analysis, the addition of cupuassu pulp improved some sensory attributes of goat milk yogurt, such as cupuassu aroma, cupuassu flavor, yellow color, consistency, and viscosity, which positively influenced product acceptance. In addition, antioxidant health information increased the acceptance and purchase intention of cupuassu goat milk yogurts. Taking into account the parameters investigated in this study, the best scoring formulation was goat milk yogurt with 10% cupuassu pulp. Our results suggest that cupuassu pulp can be considered a potential ingredient to improve the sensory and texture properties of goat milk yogurt. Furthermore, the antioxidant health information could be a sensory strategy to increase the acceptance of cupuassu goat milk yogurts.     

Effect of laver powder on textual,rheological properties and water distribution of squid (Dosidicus gigas) surimi gel

In order to ameliorate the gel quality of Dosidicus gigas surimi, the effects of laver powder on gel properties, rheological properties, and water-holding capacity (WHC) were investigated. Results indicated that the addition of laver powder could significantly increase the hardness, chewiness, and breaking force of surimi gels. However, the texture indexes and gel strength began to decline when additional amount exceeded 0.6%. Rheological results demonstrated that the addition of laver powder increased the storage modulus (G′) and viscosity of surimi, prolonged protein denaturation temperature in surimi gels. Moreover, the WHC of surimi gel was improved with the increase of laver powder. Further analyses in low-field nuclear magnetic resonance revealed that laver powder could shorten the transverse relaxation time, enhanced the combination with water, and altered the distribution of different water categories. The proportion of bound water and immobilized water reached its maximum and minimum at 0.6% of laver powder, respectively. Correlation analyses showed that WHC of surimi gel was negatively correlated well with the proportion of loose-bound water, but positively correlated with the strong-bound water and free water. In conclusion, the results supported that 0.6% was the optimal additional amount of laver powder for the squid-based surimi production based on the current ingredients of surimi products.     

Heat treatments of peptides from oyster (Crassostrea gigas) and the impact on their digestibility and angiotensin I converting enzyme inhibitory activity

Food Science and Biotechnology - The changes of protein digestibility, the peptides in the digestive juice and angiotensin I converting enzyme (ACE) inhibitory activity after heating of oysters...     

Temperature Effects on the Depuration of Vibrio parahaemolyticus and Vibrio vulnificus from the American Oyster (Crassostrea virginica)

ABSTRACT:  This study investigated temperature effects on depuration for reducing Vibrio parahaemolyticus and Vibrio vulnificus in American oyster ( Crassostrea virginica ). Raw oysters were inoculated with 5-strain cocktail of V. parahaemolyticus or V. vulnificus to levels of 10⁴ to 10⁵ MPN (most probable number)/g and depurated in artificial seawater (ASW) at 22, 15, 10, and 5 °C. Depuration of oysters at 22 °C had limited effects on reducing V. parahaemolyticus or V. vulnificus in the oysters. Populations of V. parahaemolyticus and V. vulnificus were reduced by 1.2 and 2.0 log MPN/g, respectively, after 48 h of depuration at 22 °C. Decreasing water temperature to 15 °C increased the efficacy of depuration in reducing V. parahaemolyticus and V. vulnificus in oysters. Reductions of V. parahaemolyticus and V. vulnificus in oysters increased to 2.1 and 2.9 log MPN/g, respectively, after 48 h of depuration at 15 °C. However, depurations at 10 and 5 °C were less effective than at 15 °C in reducing the Vibrio spp. in oysters. Extended depuration at 15 °C for 96 h increased reductions of V. parahaemolyticus and V. vulnificus in oysters to 2.6 and 3.3 log MPN/g, respectively.     

Effects of the perception of traceable fresh food safety and nutrition on perceived health benefits,affective commitment,and repurchase intention

Because numerous food safety problems have gained public attention, consumers are now focused on food safety and nutrition as well as health benefits. While traceability is considered the most effective intervention to ensure food safety, understanding how to encourage consumers to purchase traceable fresh food (TFF) is crucial in developing the safe food market. A questionnaire survey was conducted in Taiwan to explore the effects of the perception of TFF safety and nutrition on perceived health benefits, affective commitment, and repurchase intention. TFF consumers, defined as those who had purchased TFF in the past three months, were asked to participate in the study; in total, 393 valid questionnaires were collected. Results of structural equation modeling analysis indicated that consumers’ TFF safety and nutrition perception affected their health benefit perceptions, which consequently influenced their affective commitment to TFF and repurchase intentions. These findings explain how TFF repurchase intentions are influenced by TFF safety and nutrition perception and health benefit perceptions. This paper provides some practical suggestions for TFF marketers to increase TFF consumption.     

Consumer perception of boar meat as affected by labelling information,malodorous compounds and sensitivity to androstenone

This study aimed to assess the influence of two label conditions on the acceptance of boar meat. A central location test was conducted with 145 consumers each assessing 4 pieces of pork loin.     

基于仿生智能算法的高水分玉米收购定等系统研究（网络首发、推荐阅读）

人工智能技术在解决传统农业难题方面表现出了无可比拟的优势。目前,粮食收购中对高水分玉米的水分含量和等级判定仍然以人工感官检测为主,存在工作量大、效率低、重复性差、主观性强等问题,影响企业效益和农民利益。针对玉米高水分快速检测的技术难题,采用机器视觉技术在挖掘玉米图像丰富信息的基础上,以互信息熵为耦合程度作为评价指标,研究了高水分玉米图像快速无损检测新方法及智能收购定等系统,并对系统进行了测试。结果表明,在实现“机器看水”仿生智能算法的基础上,进行高水分玉米收购定等是一条值得探索的技术路径。