Sensory characteristics and storage quality indicators of surimi franks nutritionally enhanced with omega‐3 rich flaxseed oil and salmon oil

Surimi franks were fortified with flaxseed or salmon oil at 2 g/100 g sample, franks without added oil served as a control. Thiobarbituric acid reactive substances values were highest (P < 0.001) in salmon oil franks; however, these values did not change over the 21‐day storage period regardless of frank type (P > 0.05). Frank pH decreased over time (P = 0.011) for all frank types. There were differences in textural properties between frank types (P < 0.05), with the flaxseed franks being softer and less gummy, cohesive and chewy than the control franks. Participants (n = 79; age 18–35) evaluated visual appeal, colour, aroma, texture, flavour and acceptability on a hedonic scale; there were no differences (P > 0.05) between franks. Fifty‐four panellists reported consuming sausage on a weekly to monthly basis, and most (50/79) indicated interest in purchasing this type product. The surimi franks were accepted by young adult consumers, which may indicate market potential of these types of products.     

Preparation and characterization of high‐quality rice bran proteins

Rice bran contains 120–200 g kg^?1 protein in addition to a large amount of fat, carbohydrate, and phytic acid. Rice bran protein (RBP) fractions were refined by a two‐step preparation to eliminate residual carbohydrate. The first step involved the sequential extraction of defatted rice bran into RBP fractions using their distinct solubility to give 37 g kg^?1 of albumin, 31 g kg^?1 of globulin, 27 g kg^?1 of glutelin, and 2 g kg^?1 of prolamin. In the second step, carried out by dissolving in respective solvent and isoelectric precipitation, the protein content of each fraction increased from 69% to 97% for albumin, from 71% to 90% for globulin, from 74% to 83% for glutelin, and from 18% to 20% for prolamin. The low protein content in the prolamin fraction might be due to its low solubility in the protein assay. Emulsifying stability index and surface hydrophobicity increased in the second‐step preparation of albumin and globulin, but not of glutelin. Emulsifying properties of RBPs were lower than that of a soybean protein isolate. Denaturation temperatures and enthalpy values of denaturation for albumin, globulin, glutelin, and prolamin were 50.1 °C/1.2 J g^?1, 79.0 °C/1.8 J g^?1, 74.5 °C/3.0 J g^?1, and 78.5 °C/8.1 J g^?1, respectively. No significant differences in the denaturation temperatures and enthalpy values of denaturation of RBP fractions were obtained with these two‐step preparations (P < 0.05). Copyright © 2007 Society of Chemical Industry     

食用植物油加工质量的影响因素及控制

食用植物油生产加工过程中,存在诸多因素影响油脂的质量,如:原料,采购中质量验证不到位,原料储存条件不符合要求,质量检验措施不足;生产加工环节,油料的清理程度不够,油脂的精炼方案不够完善以及相关参数缺乏准确性,关键控制点的确定不准确或不够,生产作业指导书的制定缺乏完整性;车间布局和设施,车间布局欠合理,没有按要求对灌装区域和其他作业区分隔,工作人员净化方面不足;企业管理方面,管理体系不完善,缺乏现代管理理念和措施等。针对以上方面存在的问题,结合生产实际进行了分析探讨,并提出了解决措施以保证食用植物油质量。     

Effects of high‐pressure processing and enzymatic dephosphorylation on phosvitin properties

BACKGROUND: Egg phosvitin could be a good source of functional peptides. Enzymatic dephosphorylation and high‐pressure processing combined with thermal treatment applied before proteolysis could produce phosvitin hydrolysates with different properties compared to its native form. RESULTS: Phosvitin structure was maintained overall during high‐pressure treatment of 600 MPa applied at an initial temperature of 65 °C regardless of the pH and duration of treatment, confirming the high structural stability of this phosphoprotein. Treatment of phosvitin with phosphatase increased the degree of dephosphorylation from 24% to 63%, after 2 and 18 h, respectively. Moderate dephosphorylation of phosvitin prior to proteolytic digestion improved its hydrolysis, allowing formation of peptides with a molecular weight lower than 17,000 kDa as determined by size exclusion chromatography. Angiotensin‐converting enzyme (ACE) inhibition and antioxidant activity of dephosphorylated and protease‐treated phosvitin was increased by 52% and 39%, respectively, as compared to protease‐digested native phosvitin. CONCLUSION: Enzymatic dephosphorylation before proteolysis mimicking in vivo gut conditions improved ACE inhibition and antioxidant activity of phosvitin hydrolysates. Copyright © 2012 Society of Chemical Industry     

Effects of high-pressure processing on proteolytic enzymes and proteins in cold-smoked salmon during refrigerated storage

The present paper describes the effects of high-pressure processing on the activity of proteolytic enzymes in cold-smoked salmon and enzyme extracts for pressures up to 300 MPa. The activities of the three enzymes, cathepsin B-like, cathepsin B + L-like and calpains were reduced at all pressure levels of up to 300 MPa (at ca. 9 °C for 20 min) in crude enzyme extracts prepared from cold-smoked salmon. Calpain almost completely inactivated at 300 MPa. High-pressure did not influence general proteolytic activity but activated the enzymes in muscles at higher pressure levels studied until 18 days of storage. An increase in the activity of cathepsin B + L-like and calpain was seen after 12 days of refrigerated storage. Myosin heavy chain was less affected at higher pressure levels (300 MPa) only as shown by Sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE) of proteins and further refrigerated storage had no obvious effects on proteins.     

Influence of the malaxation time and olive ripening stage on oil quality and phenolic compounds of virgin olive oils

The main objective of this study was to evaluate the influence of the malaxation time (Mt) and ripening stage on oil quality and phenolic compounds of Hojiblanca and Picual virgin olive oils. In both varieties of oil, phenolic content and oxidative stability decreased as ripening progressed. The total level of tocopherols diminished by up to 40% as fruit ripened. The compositions of palmitic, stearic, lignoceric, oleic, linoleic and linolenic acids were significantly influenced by the ripening process. The present work shows that an increased Mt promoted the increase of free acidity (up to 13.3%) and tocopherols (up to 11.6%) and negatively affected the oxidative stability and the concentration of phenols. Further research is required to determine ripening stages and malaxation conditions for all olive oil varieties to achieve a satisfactory balance between the improvement of both oil yield and oil quality and composition.     

Gelation enhancement of soy protein isolate by sequential low‐ and ultrahigh‐temperature two‐stage preheating treatments

The effects of combined two heating steps with low (LT, 60 °C for 1 h) and ultrahigh (UHT, 130 or 140 °C for 4 s) temperatures on the thermal gelation of soy protein isolate (SPI) were studied. UHT pretreatments significantly increased protein solubility and enhanced the gelling potential of SPI. Yet, the two‐stage preheating treatment with LT and then UHT‐130 °C had a most remarkable effect: the gel strength of the SPI₆₀₊₁₃₀ sample was, respectively, 1.45‐, 1.64‐ and 3.19‐fold as strong as those of SPI₆₀, SPI₂₅₊₁₃₀, and SPI₂₅. In comparison with single LT or UHT treatments, this two‐stage heating also produced greater amounts of soluble protein aggregates stabilised predominantly by disulphide bonds and hydrophobic forces, contributing to the improved gel network structure.     

Possibility of improving the quality characteristics of olive‐pomace oil and enhancing its differentiation from refined olive‐pomace oil

An investigation was carried out to evaluate the oxidative and hydrolytic degradation of 37 olive‐pomace oils marketed in southern Italy and to compare the results with those obtained from 10 deodorised olive‐pomace oils representative of large stocks of oil obtained after the final step of refining. One aim of the research was to ascertain the quality characteristics of commercial olive‐pomace oils; another was to verify whether the legally prescribed addition of virgin olive oil to refined pomace oil, so that the final product may be classified commercially as olive‐pomace oil, was actually sufficient to justify upgrading. The analytical methods used were silica gel column chromatography and high‐performance size exclusion chromatography. The data obtained showed that the final retail olive‐pomace oils had a lower degree of oxidative degradation than the refined oils, as indicated by the lower values obtained when summing the proportions of triglyceride oligopolymers and oxidised triglycerides. Conversely, hydrolytic degradation, which was evaluated by determining diglycerides, proved to be the same in the two categories of oil. The proportions of virgin olive oil added are small, as indicated by the statistically indistinguishable values of triglyceride oligopolymers and free fatty acids obtained. The possibility of setting a limit to the amount of triglyceride oligopolymers present in the commercial category of olive‐pomace oil has been considered. This limit would ensure standardisation of the level of oxidation and, consequently, of the quality of marketed oils and would enhance differentiation between olive‐pomace oil and refined olive‐pomace oil. © 2000 Society of Chemical Industry     

胶原/壳聚糖抗菌海绵衬垫对三文鱼品质变化的影响

将生鲜三文鱼肉进行抗菌海绵衬垫覆PE膜包装、PP衬垫覆PE膜包装以及空白组覆PE膜包装,在4℃条件下贮藏,以感官评定、失重率、pH值、色差值、质构值、挥发性盐基氮(TVB-N)以及菌落总数为评价指标,研究抗菌海绵衬垫对冷藏三文鱼的保鲜效果。结果显示:在贮藏期间,各组三文鱼肉的感官评分值呈下降趋势;失重率、色差值、挥发性盐基氮及菌落总数呈上升趋势;pH值呈先降低后上升的趋势。除失重率外抗菌海绵衬垫组包装的三文鱼片各项评价指标均优于PP衬垫组与空白组,抗菌海绵衬垫可延长三文鱼肉的冷藏货架期2～4d。     

加工部位及提取工艺对沙棘油品质特性及主要脂质伴随物油相迁移的影响

比较分析了不同加工部位及提取工艺对沙棘油得率、品质特性及主要脂质伴随物的影响规律。结果表明:与果肉油和全果油相比,沙棘籽油具有较低的酸价、过氧化值、p-茴香胺值、K232值和K270值,且具有较高的得率、α-亚麻酸和植物甾醇含量;沙棘果肉油和全果油则具有较高的生育酚、类胡萝卜素和总酚含量。与传统溶剂提取(SE)和超声波辅助溶剂提取(UAE)相比,微波预处理+溶剂提取(MPE)和加速溶剂萃取(ASE)均能够显著增加沙棘油得率,但ASE同时增加了沙棘油尤其是果肉油的脂质过氧化水平; MPE能够增加沙棘油中植物甾醇和类胡萝卜素的油相迁移,而ASE则更有利于生育酚和酚类化合物的释放和油相迁移。总之,从沙棘油得率、营养品质的角度考虑,微波预处理作为一种有效的前处理方法,与短时加速溶剂萃取的联合将能够实现沙棘油的提质制取。     

水酶法提取大豆油与其他不同种大豆油品质差异研究

通过对大豆油的感官指标、理化指标及部分功能性成分的比较,研究不同种大豆油(水酶法提取大豆油、一级大豆油、三级大豆油、压榨大豆油、溶剂浸提大豆油)的品质差异。结果表明,水酶法大豆油的外观品质介于一级油与三级油之间;色泽处于二级油与三级油之间,折光率最高,密度处于一级油和三级油之间;水分及挥发物的含量和p-茴香值最高,碘价最低,酸价、过氧化值介于一级油和二级油之间;水酶法大豆油的亚麻酸未检出,其饱和脂肪酸含量最低,总不饱和脂肪酸含量最高,磷脂含量介于一级大豆油和三级大豆油之间。