超高压处理对卤制鹅胗灭菌保鲜与品质的影响

为了揭示超高压处理对卤制鹅胗灭菌保鲜与品质的影响,以100、200、300、400、500、600 MPa的压力对卤制鹅胗进行处理,保压15 min,以未经高压处理的样品为对照,室温(20±5)℃存放至第1、5、9 天测定样品的菌落总数、大肠杆菌及沙门氏菌等微生物指标,同时对样品的pH值、嫩度、色差等理化指标以及感官指标进行分析。结果表明：400 MPa以上压力保压15 min可以有效抑制大肠杆菌和沙门氏菌的生长;200～500 MPa处理对pH值的影响不显著（P＞0.05）,在9 d存放期中,pH值整体呈下降趋势,鹅胗样品中心点pH值高于边缘部位;超高压处理对嫩度没有显著影响（P＞0.05）;超高压处理对表面色差有显著影响（P＜0.05）。从感官上分析,高压处理对卤制鹅胗的口感、气味及质地等感官品质影响不显著。超高压处理不仅具有较好的杀菌效果,而且最大限度地保证了卤制鹅胗的品质。     

超高压处理对烟熏切片火腿保质期的影响

为揭示超高压处理后烟熏切片火腿中微生物、理化及感官指标的变化情况,探寻超高压杀菌应用在肉制品保鲜中的可行性,该研究以400 MPa和600 MPa的压力在12℃时对切片包装后的烟熏火腿进行10 min超高压处理,与未经高压处理作对照,4℃贮藏条件下,于0、2、4、6、8、10、12、14周测定处理后样品中的菌落总数、乳酸菌、肠杆菌及耐冷菌,同时对处理后样品的脂肪氧化值、色差值、水分活度等理化指标以及部分感官指标的变化进行了评定。试验结果表明：超高压处理对烟熏切片火腿腐败微生物具有较强的抑制作用,并随压力的升高,抑制效应增强。由于乳酸菌的繁殖,对照组2周后发生腐败变质,而经400 MPa和600 MPa高压处理组产品保质期分别延长至第8和10周。压力处理能够抑制烟熏切片火腿中的乳酸菌,使其处于相当长的低水平期（＜104 cfu/g）,促使耐冷菌和肠杆菌失去原有竞争能力,致使整个贮藏期内肠杆菌数低于102 cfu/g。超高压处理能够导致样品pH值的显著上升,感官评定认为处理后的样品硬度稍有降低,其他感官指标没有显著变化。包装后采用超高压处理能够有效抑制烟熏切片火腿中的腐败微生物,进一步延长该类肉制品的保质期。     

高压处理对牛肉感官特性与食用品质的影响

通过对宰后牛肉施加250 MPa的压力处理，分析测定处理后牛肉在贮藏期间理化指标的变化，研究了高压处理对牛肉感官品质的影响。试验结果表明高压处理能明显降低牛肉的剪切力和改善牛肉的嫩度(P<0.01)，高压嫩化的效果与肌肉的部位密切相关，压力处理对背最长肌和里脊的嫩化作用最明显。压力处理后牛肉的可溶性物质含量有所增加,但在贮藏后期差异不显著(P>0.05)，压力处理对牛肉中的游离氨基酸的影响不明显(P>0.05)，这也表明压力处理对牛肉风味的贡献与自然成熟的作用相近。通过研究可以得出结论，在室温下用250 MPa的压力处理宰后热剔骨(6小时以内)真空包装的牛肉10 min，0～4℃冷藏条件下贮存2～3 d，可获得嫩度好、其它感官指标不明显低于低温吊挂成熟7～10 d的产品。     

超高压处理对荔枝果汁品质的影响

为了探讨超高压处理对荔枝果汁品质的影响，将荔枝(“淮枝”品种)原果汁在100～500 MPa压力、10℃温度条件下处理30 min后，测定果汁的细菌总数、过氧化物酶(POD)活性及营养成分(还原糖、蛋白质、氨基酸、维生素C)等几项指标的变化。结果表明：随着压力值的上升细菌总数逐渐减少，400 MPa压力下达到商业无菌；POD的活性随压力值上升逐渐下降，在最高压力500 MPa下活性下降约55%；100～500 MPa的压力范围内还原糖含量没有显著变化，氨基酸和蛋白质的含量均随压力上升有所下降，维生素C含量在400 MPa以上的压力下出现下降趋势，500 MPa压力下约下降20%，远远小于热处理的损失。超高压处理对于荔枝果汁有很好的杀菌效果，能一定程度地钝化其中的食品品质酶，同时能较好地保持荔枝果汁中的天然营养成分，因此对荔枝加工来说是一种很有前景的冷加工技术。     

热辅助超高压对复合甜面酱品质特性的影响

该文分别从流变、色差、风味及脂肪酸组成等方面展开试验,旨在研究热辅助超高压技术对甜面酱感官品质等品质特性的影响。结果表明,复合甜面酱经热辅助超高压处理后,黏度降低,并随着压力增加,黏度逐渐下降。经300 MPa和400 MPa处理后的样品的黏度变化小于500 MPa处理的样品。经过加压处理后,甜面酱的色差值(ΔE)发生显著变化,棕色指数(browning index,BI)下降,但亮度(L*)和红绿色度值(a*)无显著变化(P0.05)。复合甜面酱中的挥发性风味物质以醛类、酯类为主,酯类含量在高压处理后减少。此外,400 MPa的热辅助超高压处理并没有对脂肪酸的组成和含量造成较大的影响。由此得知,400 MPa、45℃、10 min的热辅助超高压处理可以较好地保护复合甜面酱质地、色泽、风味等方面的品质。为热辅助超高压技术对复合调味酱的进一步研究及工业化生产提供了理论依据。     

超高压辅助脱壳处理对泥蚶肉品质的影响

为研究超高压对泥蚶脱壳率及其肌肉品质的影响,以鲜活泥蚶为材料,初步确定合适的辅助泥蚶脱壳的超高压处理参数,并在这些参数条件下,考察超高压对泥蚶肌肉色差、质构、菌落总数和氨基酸组成及其营养评价的影响。结果表明,泥蚶经300 MPa保压5 min(300/5),350 MPa分别保压3、5 min(350/3、350/5),或400 MPa保压1 min(400/1)处理,其脱壳率均达到100%,同时具有较高感官质量。在上述4组优化参数下,超高压组泥蚶肉的白度较对照组显著提高,但超高压组间的总色差值无显著差异;其硬度值提高,黏附性、弹性、内聚性和恢复度值均有所减少;泥蚶的菌落总数从5.3×10⁴ CFU·g^-1 降至10~100 CFU·g^-1;泥蚶肉氨基酸总量随压力增加而逐渐降低,其中400/1组色氨酸未检出,氨基酸总量比新鲜泥蚶肉下降7.58%,且除400/1组外,其余组泥蚶肉的蛋白均为优质蛋白。传统漂烫、超高压处理均不改变泥蚶肉第一、第二限制性氨基酸种类,分别为甲硫氨酸和色氨酸。综合超高压处理对泥蚶脱壳及泥蚶肉品质的影响,合适的工艺参数为300 MPa保压5 min以及350 MPa保压3~5 min。本研究结果为超高压脱壳技术在泥蚶加工中的应用提供了一定的理论指导。     

超高压对含有琼脂猪肉凝胶特性影响的试验

多糖作为脂肪替代物可用于开发低脂肉制品,而超高压可对低脂肌肉凝胶产生改性作用。该研究将超高压引入含琼脂0.4%猪肉糜凝胶(PMGA)的加工,在压力100～600 MPa、保压时间10～40 min、加压介质温度10～40℃范围内,单因素试验考察各因素对PMGA持水性、色泽与硬度的影响。研究结果表明:与未受压的对照组相比,200～400 MPa压力导致PMGA的蒸煮损失率显著降低(p<0.05);100～600 MPa压力可不同程度地提高PMGA的保水性,并显著降低彩度指数b*值(p<0.05);400～600 MPa压力引起PMGA亮度L*值显著增加和彩度指数a*值明显下降(p<0.05);100～400 MPa压力可显著提高PMGA的硬度,而500～600 MPa压力则显著降低其硬度(p<0.05);保压时间与介质温度对PMGA持水性、色泽与硬度的影响相对有限。因此,200～400 MPa的超高压处理可获得较高的产品出品率;且改变工作压力可调控受压PMGA的硬度。     

超高压处理对南美白对虾在冷藏过程中贮藏特性的影响

该文以不同的超高压条件(200,400,600,700MPa)对南美白对虾进行处理,通过考察与比较不同压力处理组冷藏过程中感官、微生物以及各化学指标的变化情况,揭示超高压技术对南美白对虾冷藏特性的影响。结果表明:超高压处理可以有效地杀灭南美白对虾中绝大多数微生物,抑制贮藏过程中挥发性盐基氮的积累,延缓pH值的变化,从而延长南美白对虾的货架期,且处理压力越高延长效果越显著;超高压处理会给鲜虾带来不同程度上的煮熟虾的风味;400MPa和600MPa处理使虾在冷藏过程的黑变提前,而700MPa处理可以完全抑制南美白对虾黑变现象的发生;超高压能够改变腺苷三磷酸(ATP)及其代谢产物的代谢情况,但不影响腺苷酸(AMP)的代谢途径。因此超高压处理可以改善南美白对虾在冷藏过程中的品质,对南美白对虾冷藏具有潜在的应用价值。     

超高压处理对砀山梨汁中过氧化物酶活性的影响

该文研究了超高压处理对砀山梨汁中过氧化物酶活性的影响。试验压力为0.1～500 MPa，温度为20～60℃。此外，考察了不同pH值(3～7)和保压时间(2～34 min)超高压处理对酶活性的影响。试验结果表明：在处理温度为50℃、保压时间为10 min和梨汁pH 5的条件下，300 MPa以下压力范围内高压处理酶被激活，其活性增加；大于300 MPa时酶的活性随压力增大而下降。高压处理时，温度低于40℃对酶的活性影响不大；有效影响高压处理的最小温度为40℃。保压时间超过10 min后时间延长对酶的活性影响     

超高压和热灭菌对鲜榨菠萝汁品质影响的比较

对比分析了超高压（UHP,ultra-high pressure）及热处理在达到商业杀菌要求的基础上对菠萝原汁感官品质、营养成分及理化性质的影响。试验结果表明,随着压力值（300～500 MPa）的上升菌落总数逐渐减少,超高压处理（400 MPa,26℃,10 min）及热处理（85℃,5 min）条件下均可达商业无菌;上述2种处理条件处理后菠萝原汁pH值、总酸、总糖、可溶性固形物含量与对照样差异不显著（P＞0.05）;超高压处理样品能较好地保持体系的均匀稳定性;超高压处理样品与热处理样品的L*、a*、b*值与对照样相比变化均显著（P＜0.05）,但超高压处理样品更好地保持了原有色泽;超高压处理样品的还原型维生素C保留率达94.92%,远高于热处理;感官分析通过定量描述分析法对不同处理方式处理后的样品进行分析评定,结果表明,超高压处理样品在色、香、味等方面都接近对照样。因此,超高压技术不仅具有较好的杀菌效果,而且最大限度地保证了菠萝汁的品质。     

Structural rearrangement of ethanol-denatured soy proteins by high hydrostatic pressure treatment

The effects of high hydrostatic pressure (HHP) treatment (100-500 MPa) on solubility and structural properties of ethanol (EtOH)-denatured soy β-conglycinin and glycinin were investigated using differential scanning calorimetry, Fourier transform infrared and ultraviolet spectroscopy. HHP treatment above 200 MPa, especially at neutral and alkaline pH as well as low ionic strength, significantly improved the solubility of denatured soy proteins. Structural rearrangements of denatured β-conglycinin subjected to high pressure were confirmed, as evidenced by the increase in enthalpy value (ΔH) and the formation of the ordered supramolecular structure with stronger intramolecular hydrogen bond. HHP treatment (200-400 MPa) caused an increase in surface hydrophobicity (F(max)) of β-conglycinin, partially attributable to the exposure of the Tyr and Phe residues, whereas higher pressure (500 MPa) induced the decrease in F(max) due to hydrophobic rearrangements. The Trp residues in β-conglycinin gradually transferred into a hydrophobic environment, which might further support the finding of structural rearrangements. In contrast, increasing pressure induced the progressive unfolding of denatured glycinin, accompanied by the movement of the Tyr and Phe residues to the molecular surface of protein. These results suggested that EtOH-denatured β-conglycinin and glycinin were involved in different pathways of structural changes during HHP treatment.     

高压和氯化钙结合处理对牛肉嫩度的影响

为探明高压和氯化钙（CaCl2）注射结合处理对僵直后期牛肉嫩度的影响,首先分别对CaCl2浓度、高压强度及保压时间对宰后36?h的牛背最长肌嫩度的影响进行分析,在3个单因素试验的基础上,采用Box-Behnken响应曲面中心组合设计法,对高压和CaCl2结合处理嫩化牛肉的工艺参数进行优化,并通过透射电镜对肌纤维的超微结构进行分析。结果表明：以CaCl2浓度、高压强度和保压时间为自变量,剪切力值为响应值,得到的二次多项式回归模型拟合度高（决定系数R2=0.9742）;高压强度、保压时间、CaCl2浓度、高压强度和保压时间的交互作用对牛肉嫩化效果极显著（P＜0.01）,高压强度和CaCl2浓度的交互作用对牛肉嫩化效果显著（P＜0.05）。高压和CaCl2结合处理嫩化牛肉最佳工艺为：高压强度241?MPa,CaCl2浓度0.24?mol/L（样品质量5%的注射量）,保压时间14?min。应用此工艺嫩化牛肉,和对照相比牛背最长肌剪切力值下降了52.98%,肌纤维间隙增大,肌节完整性遭受破坏,牛肉嫩度明显改善。     

高静压处理改善白果蛋白致敏性和功能特性

为了研究高静压处理对白果蛋白结构、抗原性及功能特性的影响,分别采用100,200,300,400,500,600和700 MPa的压力对白果蛋白进行处理,采用酶联免疫吸附检测法测定蛋白的致敏性,分别采用聚丙烯酰胺凝胶电泳,圆二色谱,荧光光谱和紫外吸收光谱检测白果蛋白分子量和构象的改变,功能特性的检测包括热稳定性和乳化特性。结果表明,高静压处理在300~700 MPa范围内可显著降低白果蛋白的致敏性(P0.05),同时高压处理后,白果蛋白能被分解为分子量为4~30 k Da范围内的小分子蛋白,此外,其二级结构中的α-螺旋和β-折叠结构被大量破坏形成无规则卷曲结构,其紫外吸收强度,表面疏水性和游离巯基含量明显提高(P0.05),高压对白果蛋白的致敏性影响与其结构变化密切相关,另外高压处理(300~700 MPa)可明显改善白果蛋白的热稳定性和乳化性能(P0.05)。因此,高静压技术可以作为一种降低白果蛋白致敏性和改善其功能特性的有效手段。     

Effect of high-pressure treatment on lipoxygenase activity

Solutions of commercial soybean lipoxygenase (100 microgram/ML in 0.2 M citrate-phosphate and 0.2 M Tris buffer were subjected to pressures of 0.1, 200, 400, and 600 MPa for 20 mm. The enzyme was stable at atmospheric pressure (0.1 MPa) over a wide pH range (5-9). In citrate phosphate buffer, the enzyme had maximum stability over the pH range 58 in untreated samples and after treatment at 200 MPa, but with increasing pressure, the pH stability range become narrower and centered around pH 78. The enzyme was more sensitive to acid than alkali, and at pH 9, it lost virtually all activity after pressurization at 600 MPa for 20 mm in both buffers. The activity of the crude enzyme extracted from tomatoes treated at 200 and 300 MPa for 10 mm was not significantly different from that of the untreated tomatoes, while a pressure of 400 MPa for 10 mm caused a significant decrease in activity and treatment at 600 MPa led to complete and irreversible activity loss. Compared to unpressurized tomatoes, treatment at 600 MPa gave significantly reduced levels of hexanal, cis-3-hexenal, and trans-2-hexenal, which are important contributors to "fresh" tomato flavor, and this was attributed to the inactivation of lipoxygenase.     

基于可见-近红外光谱的滩羊肉多品质指标无损检测

针对近红外光谱技术在生鲜肉品质检测中预测模型适用范围窄、检测指标单一、模型稳定性差、难以有效应用于生产检测等问题,本研究采集不同月龄宁夏滩羊宰后3个时期4个部位肉的可见-近红外光谱信息,测定色泽、pH值、蒸煮损失、剪切力以及蛋白质、粗脂肪和水分含量,利用2个波段(370~1 050 nm、900~1 700 nm)的光谱数据分别构建各个指标的偏最小二乘回归(PLSR)预测模型以实现滩羊肉多品质指标同步无损检测。结果表明,两波段中各品质指标的PLSR预测模型相关系数(R)均大于0.80,第二波段中水分含量PLSR模型预测集R可达0.941;两波段中各品质指标预测模型的性能较好,其中370~1 050 nm波段的光谱数据对样品色泽参数预测效果更好。综上所述,可见-近红外光谱技术可实现滩羊肉7个品质指标的快速无损检测。本研究结果为滩羊肉品质控制和滩羊屠宰加工企业优质特色产品的生产提供了技术支撑。     

Effects of high hydrostatic pressure on some functional and nutritional properties of soy protein isolate for infant formula

The effects and mechanism of high hydrostatic pressure (HHP) on some functional and nutritional properties of soy protein isolate (SPI) for infant formula were investigated. Results indicated that solubility, water holding capacity, emulsification activity index, and foaming capacity were improved at lower pressure and time levels, whereas these properties declined at higher levels. However, the emulsification stability index dropped when the pressure increased and the foaming stability decreased with pressure and time levels rising. HHP-treated SPI gave better swallowing properties and in vitro digestibility than control. The hardness, adhesive force, and springiness of SPI gels increased with increaded pressure and elongated time, being lower than those of the control. Near UV circular dichroism spectra confirmed the alteration of tertiary and/or quaternary conformations caused by HHP. Sodiumdoecyl sulfate polyacrylamide gel electrophoresis results indicated that β-conglycinin was more pressure labile than glycinin, and high molecular weight subunits formed via disulfide linkage at higher treatment levels.     

高静压加工对黄桃罐头品质的影响（英）

为拓展非热加工技术在水果罐头加工中应用,以黄桃罐头为试材,研究了高静压加工对黄桃罐头品质的影响。分析了黄桃罐头果肉或汤汁的质地、显微结构、色泽、pH值、可滴定酸和可溶性固形物在加工前后变化,并与传统热加工产品进行比较。结果表明：高静压加工（600 MPa, >5 min）能有效地保持产品质地、显微结构、色泽、pH值、可滴定酸和可溶性固形物,而热加工（90±2°C, 20 min）导致果肉质地软化、显微结构破坏及可溶性固形物增加,严重影响产品品质。同时感官分析表明,与对照相比,高静压加工黄桃罐头除新鲜度及滋味稍差外,其他方面均无明显差别,而热处理黄桃罐头除保持较好色泽与香气外,其他方面均产生劣质的影响。所得研究结果将为高静压技术在水果罐头中工业化应用提供理论依据。     

年龄对牦牛平滑肌胶原蛋白含量和质构特性的影响

为研究年龄对牦牛平滑肌胶原蛋白含量和质构特性的影响。研究了1～6岁牦牛瘤胃平滑肌中的胶原蛋白含量、溶解性和交联度以及剪切力和质构变化。结果表明:随年龄的增加,牦牛平滑肌中总胶原蛋白、不可溶性胶原蛋白、吡啶诺林含量显著增加(P0.05),增幅分别为7.61%、33.86%和196.46%;可溶性胶原蛋白含量和溶解性显著下降(P0.05),降幅分别为30.80%和35.72%;表明随着年龄增加平滑肌中胶原蛋白的交联度增加、溶解性降低。牦牛平滑肌的剪切力、硬度和咀嚼性随年龄增加而显著增加(P0.05),增幅分别为96.48%、91%和102%;内聚性、弹性和胶着性随年龄增加而显著降低(P0.05),降幅分别为25%、32%和39%;表明平滑肌的质构随年龄增加而呈现劣变趋势。相关性分析表明年龄与牦牛平滑肌总胶原蛋白含量、不可溶性胶原蛋白含量、交联度、剪切力、硬度和咀嚼性呈极显著正相关(P0.01);与可溶性胶原蛋白含量、胶原蛋白溶解性、内聚性、弹性和胶着性呈极显著负相关(P0.01);牦牛平滑肌胶原蛋白的溶解性和交联度均与剪切力和质构指标呈极显著相关(P0.01)。综合来看,年龄对平滑肌的胶原蛋白含量、溶解性、交联度和质构有显著影响;年龄越大平滑肌胶原蛋白交联度越大、溶解性越小、质构品质越差,3岁是牦牛平滑肌加工利用的适宜年龄。研究结果明确了不同年龄平滑肌的胶原蛋白特性和质构品质的变化规律,以及胶原蛋白特性对其质构品质的影响,将为平滑肌及含平滑肌内脏的产品开发和品质控制提供理论依据和数据支持。     

Effect of ultrahigh hydrostatic pressure on the activity and structure of mushroom (Agaricus bisporus) polyphenoloxidase

High hydrostatic pressure (HHP, treatment pressure ≤700 MPa) is approved to be the most successful commercial nonthermal processing due to its minimal modifications in nutritional and sensory quality. However, for some pressure stable enzymes such as PPO, this unique technology can hardly inactivate them at treatment pressure below of 700 MPa. This study investigated the effects of ultrahigh hydrostatic pressure (UHHP, treatment pressure >700 MPa) on the activity of Agaricus bisporus mushroom polyphenoloxidase (PPO) both in the phosphate buffer and in the mushroom puree, and on the structure of the enzyme by means of circular dichroism (CD), fluorescence emission spectra, and sulphydryl group detection. The results showed that UHHP treatment at pressure from 800 to 1600 MPa caused significant inactivation on the PPO both in the phosphate buffer and in the mushroom puree. UHHP treatment at 1400 and 1600 MPa for 1 min reduced the enzyme activity by 90.4% and 99.2% in the buffer;, however, higher enzyme activity remained in the puree after UHHP treatment at the same condition. CD and fluorescence spectra analysis showed that the secondary and tertiary structures of UHHP treated mushroom PPO were changed. The sulphydryl group (SH) detection revealed that the SH content on the surface of UHHP treated mushroom PPO was increased. It has been suggested that the inactivation of mushroom PPO by UHHP treatment at pressure higher than 1000 MPa was due to the synergistic effect of the pressure and the heat arising from pressurization, in which heat plays a major role.     

Hydrophobic probe binding of beta-lactoglobulin in the native and molten globule state induced by high pressure as affected by pH,KIO(3) and N-ethylmaleimide

High hydrostatic pressure (HHP) at 500 MPa and 50 degrees C induces beta-LG into the molten globule state. Retinol, cis-parinaric acid (CPA), and 1-anilino-naphthalene-8-sulfonate (ANS) fluorescence from pH 2.5 to 10.5 in the presence of the native and molten globule states of beta-LG indicate that retinol binds to beta-LG in the calyx, CPA at the surface hydrophobic site, and ANS in multiple hydrophobic sites. HHP treatment results in a decrease of beta-LG affinity for retinol and CPA, suggesting conformational changes in the calyx and surface hydrophobic site of beta-LG during HHP treatment. beta-LG treated by HHP in the presence of N-ethylmaleimide (NEM) retains retinol affinity, suggesting that NEM protects the calyx conformation of beta-LG during HHP treatment. HHP treatment of beta-LG in the presence of KIO(3) exhibits a great decrease of CPA affinity compared to HHP-treated beta-LG in the absence of KIO(3), suggesting the formation of non-native disulfide bonding at the CPA binding site.