超高压处理对冷藏鲍鱼保鲜效果与品质变化的影响

本文以鲍鱼为材料,研究了超高压处理对鲍鱼体内微生物的消减作用和不同压力超高压处理后的鲍鱼在冷藏过程中挥发性盐基氮值、p H、脂肪氧化值、肌肉组织与硬度的变化情况,对比了热加工和超高压处理对鲍鱼品质变化的影响。研究结果显示,超高压具有良好的杀菌效果,鲍鱼经400 MPa和500 MPa处理10 min,体内菌落总数达到未检出状态,贮藏20 d后,仍符合生食标准。超高压处理能有效抑制鲍鱼挥发性盐基氮的产生,在4℃条件下保存30 d后TVB-N值仍小于35 mg/100 g。经超高压处理后的鲍鱼p H显著高于未加工鲍鱼,但4℃贮藏30 d后,超高压处理后的鲍鱼p H反而显著低于未加工鲍鱼;相比热加工和未加工的对照条件,超高压处理能延迟TBA值的升高,抑制脂肪氧化;组织切片和质构实验发现经超高压处理的鲍鱼肌肉纤维凝聚,肉质硬度升高,但随着贮藏时间的延长,硬度逐渐下降。结果表明,鲍鱼经400 MPa压力处理10 min,冷藏20 d后仍可生食,同时品质得到良好的提升。      

超高压-限制性酶解法降低豆乳粉致敏性工艺优化

以传统湿法工艺技术制备豆乳粉为基础,对浆渣分离后的豆乳进行超高压-限制性酶解处理,降低豆乳粉致敏性。在单因素试验基础上,采用响应面分析法对超高压-限制性酶解制备低致敏性豆乳粉工艺进行优化,确定最优超高压-限制性酶解的工艺参数为超高压处理压强320.00?MPa、超高压处理时间15?min、酶解时间60?min、酶添加量0.3?U/g,此条件下致敏性降低率为88.09%,但制备的豆乳粉具有微苦味,需要进一步调配以改善口感。超高压处理与酶解具有协同效应,可显著提高豆乳粉蛋白质体外消化率、显著降低豆乳粉致敏性,对不同加工工艺豆乳粉进行蛋白质体外消化率、蛋白质分散指数、过敏原含量及蛋白电泳分析,进一步证明超高压与酶解的协同效应。     

超高压及超高温瞬时灭菌对西瓜饮料品质的影响

研究400 MPa不同加压时间与超高温瞬时（ultra high-temperature,UHT）灭菌对调配西瓜饮料品质的影响。以未经灭菌的调配西瓜饮料为对照,运用流变仪、电子鼻等设备研究不同处理西瓜饮料菌落总数、内源酶、流体类型、黏度及风味的变化。结果表明：加压时间越长,对菌落总数抑制、多酚氧化酶及果胶甲酯酶钝化作用越强;西瓜汁假塑性越明显;且风味与对照组差异越明显;400 MPa、20 min超高压处理与UHT处理对调配西瓜饮料部分品质影响相似,但在保持西瓜饮料风味及色泽等方面优于UHT处理。     

超高压处理对低磷酸盐鸡胸肉盐溶蛋白凝胶的影响

采用混料回归试验设计方法,对300MPa、25℃、10min超高压处理鸡胸肉盐溶蛋白所添加的低含量复合磷酸盐的配比情况进行研究。结果表明:为达到良好的保水性能,未经超高压处理样品的最佳复合磷酸盐配比为m(焦磷酸钠(DSPP)):m(三聚磷酸钠(STPP)):m(六偏磷酸钠(HMP))=41:42.3:16.7,高压处理样品的最佳复合磷酸盐配比为m(DSPP):m(STPP):m(HMP)=38.9:44.4:16.7。超高压处理过的鸡胸肉盐溶蛋白凝胶的保水性比未经高压处理组样品显著提高。对照组DSPP、STPP以及DSPP、HMP的协同作用对保水性的影响较大,高压组则为DSPP、HMP以及STPP、HMP的协同作用对保水性影响比较大。在100MPa时,质量分数0.15%复合磷酸盐添加的鸡肉糜制品可以达到与质量分数0.30%复合磷酸盐添加的鸡肉糜制品的保水性相似的效果,初步说明可以在生产中使用超高压处理以达到减少复合磷酸盐的添加量而不显著影响制品保水性的效果。     

Enzyme Activity and Nutritional Quality of Peach (Prunus persica) Juice: Effect of High Hydrostatic Pressure

The inactivation of polyphenol oxidase and pectin methylesterase in peach juice was investigated after high hydrostatic pressure processing at 400–600 MPa and 25°C for 5–25 min, respectively. At 400 MPa, polyphenol oxidase and pectin methylesterase were activated by 7.3 and 2.6%. At 500 and 600 MPa, polyphenol oxidase and pectin methylesterase were inactivated significantly with increasing the pressure and time, and the inactivation kinetics was fitted by the first order model. Moreover, some physio-chemical properties were studied. The results revealed that high hydrostatic pressure treatment preserved more L-ascorbic acid and maintained the color and sensory quality better than thermal treatment.     

Effect of High Pressure Processing on Rheological Properties,Pectinmethylesterase Activity and Microbiological Characteristics of Aloe Vera (Aloe barbadensis Miller) Juice

Effect of pressure level (60–740 MPa), process dwell time (3–40 min), and pH (2.32–5.68) on rheological properties, pectinmethylesterase (PME) enzyme activity and microbiological characteristics of aloe vera juice was studied. A quadratic model was developed for rheological parameters and it was found that pressure level had the most significant effect on all the responses (p < 0.05) followed by pH and dwell time. Pectinmethylesterase activity was evaluated and a maximum of up to 30% inactivation was obtained. Microbial analysis of high pressure treated samples revealed that samples treated at 400 MPa for 20 min at pH 4 reduced microbial counts to <10 cfu mL^?1 achieving up to 5.66 log cycle reduction.