超高压处理对再制奶油干酪质构、流变学特性及微观结构的影响

以低饱和脂肪酸的再制奶油干酪为研究对象,探究不同条件超高压处理(压力:150、300、450MPa;保压时间:10 min;保压温度:25℃)对再制奶油干酪质构、流变学特性及微观结构的影响.通过SPSS软件分析压力变化与干酪水分质量分数、水分活度、pH值及质构特性的相关性,通过质构分析仪测定干酪质构特性(涂抹性、硬度、...     

超高压处理对鳙鱼质构特性的影响

研究不同超高压条件(150、300、450MPa,保压15min)对鳙鱼质构特性的影响。结果表明,300MPa和450MPa处理可以显著提高鱼肉的粘着性和咀嚼性(p<0.05),优化感官品质。观察鱼肉的超微结构发现,用450MPa处理后出现明显的蛋白质胶凝化现象。用300MPa和450MPa处理后降低了肌原纤维断裂指数(p<0.01)和持水力,提高了鱼肉的pH值(p<0.01)。因此超高压处理在改良鳙鱼肉质方面具有潜在的应用价值。     

超高压处理对酱卤鸡腿品质及货架期的影响

为探究超高压处理对酱卤鸡腿品质及货架期的影响,实验设置超高压组处理条件为200、400、600 MPa分别处理10 min和15 min,二次热杀菌组处理条件为80℃/30 min。结果表明:超高压600 MPa/10 min和600 MPa/15 min组汁液损失高于二次热杀菌组;超高压处理中样品亮度值随压强增加先下降后略微上升,除200 MPa/10 min处理组外,二次热杀菌组亮度值和超高压处理组无显著差异;二次热杀菌处理后样品剪切力和黏度大于超高压组;2种杀菌方式处理后样品的硬度都有所减小。超高压处理组中烷烃类和醇类风味物质大于二次热杀菌组,酮类风味物质含量小于二次热杀菌组。超高压能抑制样品中腐败菌的生长,延长产品货架期30 d。超高压处理时间越长、压强越大,对腐败菌的抑制越明显,二次热杀菌效果和600 MPa超高压相当。     

常温奶酪加工技术及货架期稳定性研究进展

对不同加工技术如热杀菌、真空干燥、超高压、盐溃、气调包装等在延长奶酪货架期中的应用进行综述,探讨了目前常温奶酪加工技术研究中存在的问题和局限,综述了不同加工技术条件对产品货架期内的微生物含量、理化指标、风味的影响,以期为常温奶酪的研究开发提供依据.     

超高压处理对鲜榨复配果汁品质及货架期的影响

为使经杀菌处理后果汁的活性成分和风味物质更接近原鲜榨果汁,本研究以猕猴桃、菠萝、芒果为原料制备复配果汁,对比超高压处理与热处理(85℃、5 min)两种杀菌方式对鲜榨复配果汁品质及货架期的影响。结果表明：复配果汁比例V_菠萝原浆:V_{猕猴桃原浆}:V_芒果原浆=4:2:4时,与传统热处理相比,在450 MPa、25℃、15 min超高压条件下处理,p H、b*值、可溶性固形物无明显差异(P>0.05),维生素C含量损失减少12.1%、多酚含量损失减少17.5%,品质更接近于未处理果汁;通过对复配果汁主要挥发性成分进行分析,烯类、酯类、醇类、酮类、醛类等风味物质的损失显著小于(P<0.05)热处理,且蒸煮味物质糠醛没有生成,丙酮和1-辛烯-3-酮相对含量分别减少68.4%、41.4%;菌落总数、霉菌和酵母菌杀菌效果均符合饮料现行有效卫生标准;通过Q₁₀模型对货架期进行预测,在4℃条件下储藏,其货架期可达到103 d。综上,超高压处理鲜榨复配果汁在有效杀灭微生物的同时更利于复配果汁保持天然品质及其货...     

超高压处理对南京盐水鸭货架期的影响

为揭示超高压(UHP)中温结合处理后南京盐水鸭货架期和品质指标的变化规律,以200MPa和400MPa的压力分别在20、30、40℃条件下对真空包装盐水鸭胸脯肉进行10min处理。4℃贮藏条件下,每周对超高压处理样品中的微生物总数、pH值、脂肪氧化程度、颜色及感官指标进行测定。结果表明:超高压能够有效地杀灭产品中的初始微生物,抑制贮藏期间的微生物生长;贮藏初期超高压处理组比未处理组样品TBARS值略有上升,随着贮藏期延长,超高压组样品TBARS值上升不明显;处理组产品的pH值高于未处理组;感官评定难以区分处理组和未处理组。超高压中温结合处理能够有效延长盐水鸭的货架期,不会或很少引发贮藏期内品质指标的变化,能够较好的保持产品原有的风味和口感品质。     

超高压处理对养殖大黄鱼风味及品质的影响

以养殖大黄鱼为研究对象,研究经超高压处理后养殖大黄鱼的营养成分、风味、色差、质构及微结构的变化。结果表明：超高压处理降低水分活度,对水分含量的影响是先升后降,提高了蛋白质含量,粗脂肪含量有明显变化（P＜0.05）。从营养成分上分析可得400 MPa、10 min的高压处理较为合适。经高压处理后,鱼肉的挥发性成分基本保留。压强、保压时间、贮藏时间对鱼肉的色泽均有影响,但在300 MPa、10 min处理条件下鱼肉的总色差与原材料无明显差异（P＞0.05）;鱼肉的硬度、黏聚性、弹性、咀嚼性随处理压强的增高也不断增大;通过扫描电镜观察,超高压处理过的养殖大黄鱼肌肉结构明显与原材料鱼肉结构不同。     

超高压处理对大蒜风味的影响

大蒜经过200、400和600 MPa保压处理20 min后,采用评分法进行感官评定,同时,采用顶空固相微萃取(SPME)富集,气相色谱-质谱联用仪(GC-MS)检测挥发性风味物,探讨超高压处理对大蒜风味的影响。结果表明:处理后大蒜中的挥发性风味成分的种类、含量都发生显著的变化,其中硫醚类物质的相对含量由处理前的54.46%变化为处理后的59.39%、41.38%和22.73%,导致感官评定中大蒜风味强度随压力增大而减弱。     

不同亲水胶体对再制奶油奶酪品质的影响

通过研究刺槐豆胶、卡拉胶、海藻酸钠、瓜尔豆胶和黄原胶5种不同亲水胶体对以切达奶酪为原料,直接酸化法得到的再制奶油奶酪品质的影响,来选择较佳的亲水胶体方案。实验结果表明,亲水胶体对样品各方面的性质影响显著,对持水性和持油性的影响尤为明显。本体系适用不凝胶的亲水胶体。黄原胶和刺槐豆胶是最佳的选择,并建议2种胶体单独使用。     

超高压处理对干酪质构的影响

研究超高压(Ultra High Hydrostatic Pressure,HHP;200,600 MPa/10min)处理对5种市售干酪的硬度、黏着性、弹性、内聚性、咀嚼性和回复性6个功能特性的影响。结果显示,5种干酪在200 MPa处理时,其黏着性、弹性、内聚性、回复性差异不显著(P0.05),即较低压力处理对干酪的质构影响不大;超高压处理后,干酪的硬度和耐咀性分别降低31%,39%,且压力越大降低越显著(P0.05);高压处理后蓝纹、稀奶油干酪的内聚性分别增加了21%,15%;帕马森、切达干酪经超高压处理其各个性质基本无显著变化,而马索里拉、蓝纹、稀奶油干酪的各个功能性均有显著差异,说明超高压处理对干酪质构的影响与水分含量有关,即水分含量越高的干酪其质构受超高压处理变化越显著。     

Effect of substituting whey cream for sweet cream on the textural and rheological properties of cream cheese

In the manufacture of cream cheese, sweet cream and milk are blended to prepare the cream cheese mix, although other ingredients such as condensed skim milk and skim milk powder may also be included. Whey cream (WC) is an underutilized fat source, which has smaller fat droplets and slightly different chemical composition than sweet cream. This study investigated the rheological and textural properties of cream cheeses manufactured by substituting sweet cream with various levels of WC. Three different cream cheese mixes were prepared: control mix (CC; 0% WC), cream cheese mixes containing 25% WC (25WC; i.e., 75% sweet cream), and cream cheese mixes with 75% WC (75WC; i.e., 25% sweet cream). The CC, 25WC, and 75WC mixes were then used to manufacture cream cheeses. We also studied the effect of WC on the initial step in cream cheese manufacture (i.e., the acid gelation process monitored using dynamic small amplitude rheology). Acid gels were also prepared with added denatured whey proteins or membrane proteins/phospholipids (PL) to evaluate how these components affected gel properties. The rheological, textural, and sensory properties of cream cheeses were also measured. The WC samples had significantly higher levels of PL and insoluble protein compared with sweet cream. An increase in the level of WC reduced the rate of acid gel development, similar to the effect of whey phospholipid concentrate added to mixes. In cream cheese, an increase in the level of added WC resulted in significantly lower storage modulus values at temperatures <20°C. Texture results, obtained from instrumental and sensory analyses, showed that high level of WC resulted in significantly lower firmness or hardness values and higher stickiness compared with cream cheeses made with 25WC or CC cream cheeses. The softer, less elastic gels or cheeses resulting from the use of high levels of WC are likely due to the presence of components such as PL and proteins from the native milk fat globule membrane. The use of low levels of WC in cream cheese did not alter the texture, whereas high levels of WC could be used if manufacturers want to produce more spreadable products.     

Short communication: Low-fat ice cream flavor not modified by high hydrostatic pressure treatment of whey protein concentrate

The purpose of this study was to examine flavor binding of high hydrostatic pressure (HHP)-treated whey protein concentrate (WPC) in a real food system. Fresh Washington State University (WSU, Pullman) WPC, produced by ultrafiltration of separated Cheddar cheese whey, was treated at 300 MPa for 15 min. Commercial WPC 35 powder was reconstituted to equivalent total solids as WSU WPC (8.23%). Six batches of low-fat ice cream were produced: A) HHP-treated WSU WPC without diacetyl; B) and E) WSU WPC with 2 mg/L of diacetyl added before HHP; C) WSU WPC with 2 mg/L of diacetyl added after HHP; D) untreated WSU WPC with 2 mg/L of diacetyl; and F) untreated commercial WPC 35 with 2 mg/L of diacetyl. The solution of WSU WPC or commercial WPC 35 contributed 10% to the mix formulation. Ice creams were produced by using standard ice cream ingredients and processes. Low-fat ice creams containing HHP-treated WSU WPC and untreated WSU WPC were analyzed using headspace-solid phase microextraction-gas chromatography. Sensory evaluation by balanced reference duo-trio test was carried out using 50 untrained panelists in 2 sessions on 2 different days. The headspace-solid phase microextraction-gas chromatography analysis revealed that ice cream containing HHP-treated WSU WPC had almost 3 times the concentration of diacetyl compared with ice cream containing untreated WSU WPC at d 1 of storage. However, diacetyl was not detected in ice creams after 14 d of storage. Eighty percent of panelists were able to distinguish between low-fat ice creams containing untreated WSU WPC with and without diacetyl, confirming panelists’ ability to detect diacetyl. However, panelists were not able to distinguish between low-fat ice creams containing untreated and HHP-treated WSU WPC with diacetyl. These results show that WPC diacetyl-binding properties were not enhanced by 300-MPa HHP treatment for 15 min, indicating that HHP may not be suitable for such applications.     

High-pressure effects on the microstructure, texture, and color of white-brined cheese

Abstract: White‐brined cheeses were subjected to high‐pressure processing (HPP) at 50, 100, 200, and 400 MPa at 22 °C for 5 and 15 min and ripened in brine for 60 d. The effects of pressure treatment on the chemical, textural, microstructural, and color were determined. HPP did not affect moisture, protein, and fat contents of cheeses. Similar microstructures were obtained for unpressurized cheese and pressurized cheeses at 50 and 100 MPa, whereas a denser and continuous structure was obtained for pressurized cheeses at 200 and 400 MPa. These microstructural changes exhibited a good correlation with textural changes. The 200 and 400 MPa treatments resulted in significantly softer, less springy, less gummy, and less chewy cheese. Finally, marked differences were obtained in a* and b* values at higher pressure levels for longer pressure‐holding time and were also supported by ΔE* values. The cheese became more greenish and yellowish with the increase in pressure level. Practical Application: The quality of cheese is the very important to the consumers. This study documented the pressure‐induced changes in selected quality attributes of semisoft and brine‐salted cheese. The results can help the food processors to have knowledge of the process parameters resulting in quality changes and to identify optimal process parameters for preserving pressure‐treated cheeses.     

不同风味烧烤盐货架期分析

采用加速货架期试验法,通过提高不同风味烧烤盐的储藏温度,加快其品质变化速度,测定其水分含量、菌落总数和大肠菌群的变化,并运用货架期预测模型来预测其货架期。结果表明,不同辅料和香辛料的添加是造成不同风味烧烤盐货架期长短不同的主要原因,其中,香辣风味烧烤盐的货架期最长(298d),其次为麻辣风味烧烤盐(284d),孜然风味烧烤盐和蒜味烧烤盐的货架期最短,分别为188,174d。     

Use of chitosan to prolong mozzarella cheese shelf life

This study was undertaken to evaluate the feasibility of using chitosan, a natural antimicrobial substance, to improve the preservation of a very perishable cheese. The effectiveness of chitosan to inhibit the growth of spoilage microorganisms in Mozzarella cheese was studied during refrigerated storage. A lactic acid/chitosan solution was added directly to the starter used for Mozzarella cheese manufacturing. Mozzarella cheese samples were stored at 4°C for about 10 d and microbial populations as well as the pH were monitored. Results demonstrated that chitosan inhibited the growth of some spoilage microorganisms such as coliforms, whereas it did not influence the growth of other microorganisms, such as Micrococcaceae, and lightly stimulated lactic acid bacteria.     

Effects of ultra-high pressure homogenization on microbial and physicochemical shelf life of milk

The effect of ultra-high pressure homogenization (UHPH) on microbial and physicochemical shelf life of milk during storage at 4°C was studied and compared with a conventional heat preservation technology used in industry. Milk was standardized at 3.5% fat and was processed using a Stansted high-pressure homogenizer. High-pressure treatments applied were 100, 200, and 300 MPa (single stage) with a milk inlet temperature of 40°C, and 200 and 300 MPa (single stage) with a milk inlet temperature of 30°C. The UHPH-treated milks were compared with high-pasteurized milk (PA; 90°C for 15 s). The microbiological quality was studied by enumerating total counts, psychrotropic bacteria, lactococci, lactobacilli, enterococci, coliforms, spores, and Pseudomonas. Physicochemical parameters assessed in milks were viscosity, color, pH, acidity, rate of creaming, particle size, and residual peroxidase and phosphatase activities. Immediately after treatment, UHPH was as efficient (99.99%) in reducing psychrotrophic, lactococci, and total bacteria as was the PA treatment, reaching reductions of 3.5 log cfu/mL. Coliforms, lactobacilli, and enterococci were eliminated. Microbial results of treated milks during storage at 4°C showed that UHPH treatment produced milk with a microbial shelf life between 14 and 18 d, similar to that achieved for PA milk. The UHPH treatments reduced the L* value of treated milks and induced a reduction in viscosity values of milks treated at 200 MPa compared with PA milks; however, these differences would not be appreciated by consumers. In spite of the fat aggregates detected in milks treated at 300 MPa, no creaming was observed in any UHPH-treated milk. Hence, alternative methods such as UHPH may give new opportunities to develop fluid milk with an equivalent shelf life to that of PA milk in terms of microbial and physicochemical characteristics.     

应用Schaal耐热试验法预测软包装风味鱼的货架期

采用高温"Schaal耐热试验法"预测风味鱼的货架期。选取40、60℃2个温度进行加速实验,以加速贮藏过程中产品酸价、过氧化值及微生物的变化为指标,结合产品感官评定,依据温度与油脂货架寿命系数的关系,预测产品货架期。结果表明不添加防腐剂的产品货架期为80d,添加0.0075%山梨酸钾的产品货架期为160d。