不同冻结方式对牡蛎品质的影响

本文以冻结曲线、冻结速率、持水性、蛋白质变性程度、色差和质构为指标,研究不同冻结方式(浸渍冻结、鼓风冻结和静置冻结)对牡蛎品质的影响。结果表明:浸渍冻结组冻结速率为6.67 cm/h,分别是鼓风冻结组的5倍,静置冻结组的23倍,且其样品解冻汁液流失率和蒸煮损失最低,分别为6.75%±1.12%、42.08%±3.72%,蛋白变性程度最小,其中盐溶性蛋白含量为(48.15±5.53) mg/g,Ca²⁺-ATPase酶活为(0.202±0.020) μmol Pi/(mg·h)。浸渍冻结处理的牡蛎的弹性为(3.96±0.25) mm,与鼓风冻结组和静置冻结组比较差异显著(p<0.05)。在不同冻结方式下的色差值(L^*、a^*、b^*)、总色差(ΔE)、硬度和咀嚼性差异性不显著(p>0.05)。浸渍冻结处理牡蛎的所有品质指标都与鲜样差异不显著(p>0.05),但鼓风冻结和静置冻结在盐溶性蛋白含量、Ca²⁺-ATPase活性和弹性指标上都与鲜样差异性显著(p<0.05)。综上,浸渍冻结对牡蛎品质的保持比鼓风冻结和静置冻结更具优势,且其处理的样品品质更接近鲜样。     

Effects of Salt-curing Procedure and Smoking Temperature on Astaxanthin Stability in Smoked Salmon

ABSTRACT: The effects of salting method (injection salting compared with dry salting), smoking temperature (20°C compared with 30°C), and storage (chilled storage compared with no storage) on astaxanthin retention, surface coloration (CIE1994 L * a * b *), and process yields of cold-smoked Atlantic salmon ( Salmo salar ) fillets was investigated. An overall loss of 13% astaxanthin was observed when correcting for weight changes. Astaxanthin retention was 6.0% higher after smoking at 30°C than at 20°C ( P < 0.01). A significant decrease in astaxanthin retention (4%) was observed after chilled storage of vacuum-packaged fillets at 1°C ( P < 0.05). Salt curing was quantitatively more important to astaxanthin loss than smoking temperature and storage. Salting method did not affect astaxanthin retention, but its concentration was reduced significantly more by injection salting than with dry salting ( P < 0.01). A higher overall color change (AE) was observed for dry-salted compared with injection-salted fillets ( P < 0.001) and for fillets smoked at 30°C compared with 20°C ( P < 0.05), and this coincided with a high variability in the colorimetric parameters in these groups. Higher product yields were obtained by injection salting compared with dry salting (10%) and after smoking at 20°C compared with 30°C (2%), P < 0.001. It is concluded that choice of processing technology may have substantial impact on important quality parameters such as color stability and variation in cold-smoked Atlantic salmon.     

不同冻结方式对非发酵面团的水分状态及品质特性的影响

本实验从冻结方式的应用场合出发,对比研究了家庭常用的低温冰箱冻结（cryogenic refrigerator freezing,RF）、传统企业化生产采用的螺旋隧道冻结（spiral tunnel freezing,SF）、新兴待开发的液氮喷淋冻结（liquid nitrogen spray freezing,LF）处理对非发酵面团的水分状态、质构特性、流变学特性以及微观结构产生的影响。结果表明,3?种冻结方式的冻结速率存在明显差异,其中LF（1.33?℃/min）＞SF（0.31?℃/min）＞RF（0.08?℃/min）,且随着冻结速率减慢,面团的冻结失水率呈上升趋势,强结合水T21与弱结合水T22的峰面积比例呈下降趋势,面团的质构品质和流变学特性变差,尤其是硬度变大。由面团的微观结构分析发现,冷冻速度越慢,造成面团中的孔隙较大,面团的组织结构致密程度较差。综上,经LF处理后解冻的面团与新鲜面团的品质最相近,其次是SF和RF处理,表明新兴的LF处理比传统企业化的SF处理更有优势,而家庭常用的RF处理不利于保持面制食品的品质。     

Product Yield and Gaping in Cold-smoked Atlantic Salmon (Salmo salar) Fillets as Influenced by Different Injection-salting Techniques

Product yield and fillet gaping severity were determined in cold‐smoked Atlantic salmon fillets subjected to injection‐salting. Effects of process parameter settings (brine injection pressure, number of repeated injections, needle speed, injection of brine in 1 or 2 directions, and chilled fillet resting before smoking) were tested. Repeated injections increased the yield up to 5.3% (wt/wt). Increasing injection pressure significantly increased the severity of fillet gaping in smoked fillets by 18%. Brine injection directions or needle speed did not affect smoking yield. The stability of the injection system was high. The results show that choice of process parameter settings during injection‐salting affects product yield after smoking.     

三种冻结方式对大黄鱼品质的影响

研究了慢速冻结(SF)、酒精浸渍速冻(QF-UTE)、液氮浸渍速冻(QF-LN)三种冻结方式对大黄鱼保水性、质构特性、水分流动性等品质的影响。结果显示超低温速冻(QF-LN、QF-UTE)样品比SF冻结样品具有较小的冻结损失和解冻损失,但汁液损失和蒸煮损失较高;超低温速冻样品的硬度、胶粘性、咀嚼性、恢复性优于SF,而SF样品的黏附性、弹性和凝聚性更接近对照组;低场核磁共振横向弛豫时间数据表明冻结后结合水、不易流动水和自由水的流动性增加,且对照、SF、QF-UTE、QF-LN处理样品的三种水分组分的流动性依次增大;pT2i数据表明,QF-UTE和QF-LN处理样品的结合水和不易流动水的含量均高于SF,而自由水含量则比SF组低;核磁共振分析结果和保水性指标有良好相关性。上述结果表明可能因为速冻造成鱼肉的低温断裂,导致鱼肉质构和持水力的变化,具有较高的汁液流失和蒸煮损失。     

Freezing Rate and Frozen Storage Effects on Color and Sensory Characteristics of Pineapple Fruit Slices

This study was carried out to evaluate the influence of freezing process (cold room –18°C and air-blast freezer –50°C) and frozen storage (–18°C for 0 to 12 mo) on color and sensory quality of pineapple fruit slices (Smooth Cayenne and Red Spanish cultivars). L, –a and +b color parameters showed differences (P ≦ 0.05) with cultivar, but not with freezing rate. No differences (P ≥ 0.05) were found in sensory analysis (color and appearance) between the cultivars, frozen at different rates, compared to fresh product, or after 1 yr frozen storage. The two cultivars are suitable for freezing.     

冻结条件对酥脆香菇品质的影响

以鲜香菇为原料,经烫漂、浸渍、冻结和真空油炸等工序制得酥脆香菇。采用冻结及解冻曲线、色度仪、质构仪和扫描电镜等技术研究酥脆香菇的色彩、力学特征和组织结构,冻结和真空油炸过程香菇质构和微观形貌的变化,探索香菇酥脆质地的形成机理。结果表明,烫漂、浸渍、冷冻和真空油炸可显著改变香菇的质地和组织结构。慢速冻结有利于香菇内部水分形成大冰晶,改善酥脆香菇的色彩特征。适宜的油炸条件可使香菇天然的粗大纤维束组织结构瓦解,产生较大尺寸的孔洞,从而使真空油炸时水分迅速逸出,组织骨架固化定形,最终形成酥松脆弱的质地特征。经-20℃冷冻后真空油炸所得产品的含油量和含水量低,酥脆性佳,并呈现出较明亮、偏带红黄色调的色彩特征。     

超高压协同冷冻脱壳对南美白对虾品质的影响

本文以传统冷冻处理(FT)为对照,研究超高压协同冷冻处理(FT+200、300、400 MPa,1、3、5 min)对南美白对虾脱壳(脱壳时间、虾仁完整率及得肉率)及其品质(汁液流失率、持水性、pH、色泽和质构参数)的影响。结果表明:超高压协同冷冻处理有利于南美白对虾的脱壳,FT+300 MPa,1 min条件下脱壳时间较未处理、FT组分别缩短59.80%、13.54%,得肉率分别提高30.92%、7.25%,虾仁完整率明显提高。超高压协同处理后,由冷冻引起的汁液流失率显著降低,持水性显著提高,与未处理组鲜虾无显著差异;虾仁内部亮度L*、白度和总色差显著升高,压力≥300 MPa、保压时间≥3 min条件下虾仁呈现熟化现象;随着压力增加,虾仁硬度、咀嚼性增加,弹性下降。综合脱壳效果及其品质特性指标,FT+300 MPa,1 min处理可在显著提高脱壳效果的同时保持虾仁的良好品质,是一种较为理想的辅助脱壳手段。     

不同冻结温度及冻融循环处理对蓝莓品质特性的影响

研究冻结温度和冻融循环次数对蓝莓果实品质的影响。以4℃冷藏为对照组,考察冻结温度在-10、-18、-25和-80℃下蓝莓硬度、可溶性固性物、可滴定酸、抗坏血酸、花青素和丙二醛含量等品质指标的短周期变化;再进行1、2、3和4次冻融循环,重复测定上述品质指标和裂果率、解冻损失率等物理指标。结果表明,较于对照组,-80℃冷冻组的可溶性固性物含量平均升高0.10%,而-10℃冷冻组平均降低0.17%;在贮藏期内,对照组的可滴定酸含量下降0.35%,而-80℃冷冻组仅下降了0.15%;冻融次数与花青素含量、丙二醛含量和裂果率呈显著正相关,与硬度和抗坏血酸显著负相关,构建品质指标与冻融次数的回归方程,蓝莓反复冻融超过2次后,回归方程的变化趋势明显。蓝莓适宜冻结贮藏,-10℃不适宜作为蓝莓的冻结温度,-80℃速冻蓝莓品质更优,蓝莓在实际冻结贮藏和加工过程中反复冻融次数不宜超过2次。     

不同冻结方式对沙光鱼品质的影响

为了提高沙光鱼冻藏期间的品质,采用静止空气冻结、送风冻结、液氮速冻处理新鲜沙光鱼,研究不同冻结方式对沙光鱼品质的影响.以蒸煮损失率、挥发性盐基氮(TVB-N)、硫代巴比妥酸值(TBA)、K值、盐溶性蛋白含量、Ca2+-ATP酶活性为理化指标并结合冰晶观察和感官评价,考察沙光鱼冻藏过程的品质变化.结果表明:静止空气冻结、...     

不同冻结速率对温氏鸡冻结特性的影响研究

以汁液流失率、蛋白质变性、质构为指标,研究超快速冻结(11.46cm/h)、快速冻结(4.21、2.07cm/h)、慢速冻结(0.25cm/h)对温氏鸡冻结特性的影响。结果表明：随着冻结速率的增加,温氏鸡肌原纤维盐溶性蛋白含量和肌动球蛋白Ca2+-ATPase 活性的降低率、汁液流失率先呈下降趋势,然后呈增加的趋势,其他几种ATPase 活性变化不大;差示扫描量热法(DSC)分析冻结后肌肉蛋白的变性与传统方法有较好的相关性(R2=0.8367),冻结对肌球蛋白头部的变性程度要大于对肌浆蛋白和肌球蛋白尾部、肌动蛋白的变性程度;随着冻结速率的上升,温氏鸡肉的硬度和咀嚼性都有增加的趋势,而弹性和回复性都有下降的趋势。综合理化指标和质构指标,增加冻结速率利于保护温氏鸡的品质,但是过快的冻结速率破坏了其品质。     

不同冷冻方式对淡水鱼品质的影响

为了研究不同冷冻方式对淡水鱼品质的影响,以鮰鱼、鲈鱼、鳜鱼为研究对象,采用－30?℃平板、－80?℃冰箱和－80?℃液氮分别对鮰鱼、鲈鱼、鳜鱼进行冷冻处理,考察了不同冷冻方式对鮰鱼、鲈鱼和鳜鱼的解冻损失率、加压失水率、蒸煮损失率、pH值、色泽、韧性、微观组织结构、水分分布等指标。结果表明：经过－30?℃平板冷冻、－80?℃冰箱和－80?℃液氮处理后,同种淡水鱼解冻损失率、加压失水率、蒸煮损失率呈现下降趋势,其韧性呈现增大趋势,pH值无显著性变化,细胞间隙呈现下降趋势;对于同种淡水鱼,－30?℃平板冷冻组的白度最高,－80?℃冰箱和－80?℃液氮组间无显著差异（P＞0.05）;低场核磁共振结果表明,对于同种淡水鱼,相对其他两种冷冻方式,－30?℃平板冷冻处理组样品的不可移动水（T22）含量下降,自由水（T23）含量显著升高（P＜0.05）;对于不同淡水鱼,经同种冷冻方式处理后其相关指标间差异性较小。从冷冻速率和品质考虑,选择－80?℃冰箱和－80?℃液氮处理更有利于保持淡水鱼的品质。     

Bacterial Extracellular Ice Nucleator Effects on Freezing of Foods

Extracellular ice nucleators (ECINs) were incorporated into foods and subjected to subzero freezing. Time-temperature profiles, ice-formation patterns and textures were examined by thermocouple, microscopy and texture analyzer. Onset temperatures (initial freezing), enthalpies and freezing rates were measured by DSC. Addition of ECINs to liquid foods elevated ice nucleation temperatures and promoted freezing. Solid or semisolid products frozen with ECINs resulted in a fiber-like texture. These effects were more apparent at –10°C or higher. Differential scanning calorimetry revealed onset temperatures were increased 11°C by addition of ECINs, but length of time to complete the phase transition was extended at constant cooling rates. Results indicated that ECINs can be used instead of whole bacterial cells for efficient freezing and textural modification.     

冷冻预处理对刺葡萄榨汁品质的影响

冷冻预处理有利于提高葡萄榨汁出汁率,但冷冻预处理对葡萄榨汁后汁液的品质影响目前尚不清晰。将葡萄果粒在-30℃条件下冷冻至中心温度-21℃,解冻后榨汁作为试验组,将果粒4℃条件贮藏后榨汁作为对照组,研究冷冻预处理对刺葡萄汁花色苷、色差、总糖、总酸等指标的影响。结果表明,葡萄汁在4℃条件下贮藏30天后,对照组与试验组中的花色苷含量、色差、总糖、总酸含量差异均不显著。说明冷冻预处理对刺葡萄汁品质不会产生不良影响。     

快速冷冻工艺对牛肉品质和组织结构的影响

通过对比普通冷冻工艺与快速冷冻工艺对牛腱子肌的色泽、解冻汁液损失率、蒸煮损失率、剪切力指标的影响,并且结合苏木精-伊红染色法、扫描电子显微镜、透射电子显微镜观察两种冷冻工艺对牛肉组织结构的影响。结果发现：快速冷冻工艺使解冻后牛腱子肌的H值仅上升了0.9%,而普通冷冻工艺处理后的H值上升了9.4%,两种冷冻工艺对H值的影响差异显著（P＜0.05）。普通冷冻工艺处理的牛腱子肌解冻汁液损失率极显著高于快速冷冻工艺（P＜0.01）。同时,普通冷冻工艺处理的牛腱子肌的蒸煮损失率明显高于快速冷冻工艺,两者差异显著（P＜0.05）。另外,普通冷冻工艺处理的牛腱子肌的剪切力低于快速冷冻工艺和对照组,但是差异不显著。电子显微镜观察得出,普通冷冻工艺处理明显比快速冷冻工艺处理处理使解冻后牛肉的肌束间隙更大、肌原纤维间隙更大,同时普通冷冻工艺也破环了肌纤维横截面的结构。结果表明：快速冷冻工艺很好地保护了牛肉鲜艳的色泽,提高肉的食用品质。另外,快速冷冻工艺极大地降低了肉中冰晶的大小,保护了肉的组织结构,优化了肉的口感。     

不同冻结速率对鸡胸肉品质的影响

为研究冻结速率对鸡胸肉品质的影响,将24只三黄鸡屠宰并预冷8 h后取胸肉作为研究对象,样品分为3个处理组,分别置于-15、-25、-35℃下冻结,测定冻结速率、解冻汁液流失率、加压失液率、蒸煮损失率、色差、蛋白质溶解度、TBARS值、Ca2+-ATPase活力的变化。结果表明:冻结速率对鸡胸肉解冻汁液流失率、加压失液率、蒸煮损失率、色差、TBARS值、Ca2+-ATPase活力有显著影响(P<0.05),而对蛋白质溶解度无显著影响(P>0.05),且冻结速率越大,鸡胸肉品质越好。     

Biological Characteristics Affect the Quality of Farmed Atlantic Salmon and Smoked Muscle

Various biological characteristics influencing the quality of farmed salmon and smoked muscle were studied. No great differences in proximate composition were observed among raw fish. Stress produced a slight decrease in protein solubility at 0.8 M NaCl and also slight variations in electrophoretic profile. This was accompanied by a certain degree of muscle softening. Thirty-days starvation produced slight depletion of the sarcoplasmic fraction, collagen insolubilization, and muscle hardening. The effect of triploidy was more evident in sea-caged fish, resulting in lower protein solubility at 0.05M NaCl and lower insoluble collagen than diploids. After smoking, protein solubility at 0.8M NaCl was highest in stressed fish, and non-starved fish collagen became insolubilized.     

不同冻结方式对汤圆品质特性的影响

为研究不同冻结方式对汤圆品质特性的影响,采用低温冰箱冻结、螺旋隧道冻结和液氮冻结三种方式,以汤圆中心温度降至-18 ℃为标准,对其失水率、亮度、煮后汤汁透光率、质构特性、糊化特性及感官评定等品质指标进行测定与分析。结果表明,三种冻结方式汤圆失水率、煮后汤汁透光率、硬度、弹性、咀嚼性、糊化特性均存在显著性差异(p<0.05)。低温冰箱冻结:汤圆失水率高、亮度及煮后汤汁透光率最低、硬度高且弹性小、咀嚼性差、淀粉糊化程度高、口感差;螺旋隧道冻结:汤圆失水率较高、亮度及煮后汤汁透光率较低、硬度较高且弹性较小、咀嚼性较差、淀粉糊化程度较高、口感较好;液氮冻结:汤圆失水率最低,亮度及煮后汤汁透光率最高,硬度最低且弹性最大、咀嚼性优、淀粉糊化程度最低,能更好保持汤圆的品质特性,口感最好。液氮冻结是优于低温冰箱冻结、螺旋隧道冻结的冻结方式,能较好的改善汤圆品质特性。