不同冷却方式对熟制麻团品质的影响

本文通过对产品进行自然冷却、冷风冷却、真空冷却和自真混合冷却及风真混合冷却,比较5种不同的冷却处理下熟制麻团品质的变化情况。结果表明:真空冷却过程中失重率远远高于自然冷却及冷风冷却;真空冷却产品硬度和脆性较高,但弹性、色泽、感官评价均低于其他冷却方式;理化指标方面,随着贮藏时间的延长,真空冷却和混合冷却能够显著减少微生物的增长,从而达到延长货架期的目的。研究发现,采用自然冷却与真空冷却相结合的方式,既能缩短冷却时间,提高产品口感,而且能达到延长货架期的目的。     

不同冷却方式对熟制春卷品质的影响

探索自然冷却、冷风冷却、真空冷却与混合冷却4种冷却方式对熟制春卷品质的影响。将熟制春卷中心温度从80℃冷却至室温20℃,然后于4℃下贮藏18 d。对春卷冷却后的失重率、色泽、气味、质构、感官评价以及贮藏期间的pH值、菌落总数进行测定及对比。结果表明:真空冷却的冷却速率显著高于常规冷却,但产品的质量损失也显著高于常规冷却;真空冷却产品硬度和脆性较高,但色泽、形态、气味感官评价较低,混合冷却可改善真空冷却的缺点;随着贮藏时间的延长,真空冷却和混合冷却对样品pH值的影响较小,且能显著减少微生物污染,从而达到延长货架期的目的。     

真空冷却技术对低温乳化肠品质影响的研究

为了提高熟肉制品的食用品质和延长货架期,探索适当的冷却技术对熟肉制品贮藏具有重要的意义。本实验分别采用流水冷却、风冷却、真空冷却、流水和真空混合冷却方式使天然肠衣包装的乳化香肠的中心温度从80℃降至室温20℃,探究不同的降温方式对低温乳化香肠的品质和货架期影响。结果显示:混合冷却方式耗时明显低于其他单独使用的冷却方式;与真空冷却相比混合冷却方式可以明显降低产品的失水率(p<0.05)、获得更优的感官评价;风冷却使储藏期间的脂肪氧化水平明显提高(p<0.05),真空冷却和混合冷却均可延长货架期,可使乳化香肠的保质期在26d左右,比其他两种方式延长5d。本实验认为利用流水冷却和真空冷却相结合的混合冷却方式更适于天然肠衣包装的乳化型香肠的冷却。     

冷却方式对熟制鸡肉丸品质的影响

采用自然冷却、冷风冷却、真空冷却与混合冷却四种冷却方式把熟制鸡肉丸的中心温度从80℃冷却至25℃,并比较在同一温度下贮藏期间的品质变化。结果显示,混合冷却具有取代常规冷却和真空冷却的可行性。混合冷却的冷却速率显著高于常规冷却,其质量损失显著低于其他冷却方式;物性方面,真空冷却产品色泽暗,硬度大,弹性差,口感不佳,感官评定低。但在质构、色泽上混合冷却与常规冷却没有显著差异;理化指标方面,相对常规冷却而言,真空冷却和混合冷却能够显著延缓脂肪氧化和微生物污染,从而可以达到延长货架期的目的。     

冷却方式对山西小吃荞面碗托品质的影响

采用混合冷却、真空冷却对荞面碗托进行冷却,对照自然冷却的荞面碗托,对不同冷却方式获得的荞面碗托品质进行探讨。结果显示,真空冷却的荞面碗托比混合冷却和自然冷却的荞面碗托失水率大,存在显著性差异(P0.05);与自然冷却相比,混合冷却和真空冷却均可降低荞面碗托的冷却时间,但是真空冷却影响产品的感官评分。质构方面,混合冷却的荞面碗托硬度、胶着性、咀嚼性比真空冷却的小,说明混合冷却可以改善真空冷却硬度变大,咀嚼性变差的缺点;色泽方面,混合冷却的荞面碗托亮度值(L*)大于真空冷却。在相同的天数,混合冷却和真空冷却的菌落总数明显小于自然冷却,说明混合冷却和真空冷却可以延长荞面碗托的货架期。试验说明混合冷却能够改善真空冷却造成的失水率大,以及品质下降的问题,并能够比自然冷却获得较快的冷却速率和较长的货架期,在面制品中有较高的应用价值。     

真空冷却处理对冷藏米饭货架期的影响研究

以感官评价结合细菌总数为评判指标,定量评价了真空冷却处理以及后续的储藏温度对米饭货架期的影响,为货架期快速有效的估测提供了有效手段。将刚烹制的米饭分别通过自然冷却以及真空冷却处理冷却至25℃和10℃后,再分别在4、10、15℃条件下进行储藏,测定不同处理方案对米饭感官、细菌生长情况的影响,并由此建立了冷藏米饭微生物生长数学模型和货架期预测模型。结果表明:冷却方式与储藏温度对米饭的货架期均有较大影响。与自然冷却相比,真空冷却处理能显著减少米饭中细菌总数,延长米饭货架期;同时,储藏温度升高不利于米饭的保存,会导致微生物生长延滞时间显著缩短,生长速率加快,产品货架期缩短。因此,为保证冷藏米饭7d的货架期要求,可采取真空冷却至25℃,并在不高于4℃下储藏,或真空冷却至10℃,并在不高于10℃条件下储藏。     

不同冷却方式对熟制包子品质的影响

包子熟制之后需要冷却然后才能进行包装贮藏,为找到最适合熟制包子的冷却方式,文中通过对产品进行自然冷却、鼓风冷却、真空冷却和混合冷却4种不同的处理,比较其在同一温度下贮藏不同时间的品质变化。结果表明:不同冷却方式对产品保质期有不同影响(P<0.05),混合冷却方式具有取代常规冷却和真空冷却方式的可行性。混合冷却的质量损失明显低于真空冷却而冷却速率显著快于常规冷却方式;在色泽方面混合冷却可以改善真空冷却的颜色较暗这一缺点;在硬度与电子鼻分析方面混合冷却与常规冷却相比有较明显差异(P<0.05),但相对于真空冷却已有提高,在黏聚性、黏性、咀嚼性等方面混合冷却与常规冷却没有显著差异(P>0.05);感官评分的可接受性明显优于真空冷却。在化学指标测定方面:混合冷却与真空冷却对pH值变化的影响较小(P>0.05)并且可以降低包子皮的老化程度;混合冷却与真空冷却均可以显著延缓微生物污染和脂肪氧化程度,从而达到延长食品货架期的目的。     

真空冷却技术在熟肉制品工业化生产中的应用研究

真空冷却技术是依据较高温度的含水物料在密封环境中真空的条件下通过水分迅速蒸发使物料自身得到迅速降温冷却的原理,这项快速蒸发冷却技术过去仅局限应用在蔬菜和鲜花的冷却保鲜等领域中,本课题研究真空冷却技术应用在熟肉制品生产的冷却工艺中,实验结果表明:相同的熟肉产品从95℃冷却到20℃,真空冷却比传统自然冷却速度快20倍以上,该技术可有效防止微生物在产品中的污染和增殖,提高产品的质量和安全性,延长产品货架期。研究同时就真空冷却技术对产品失水率的影响作了探讨。     

不同冷却方法对馒头贮藏过程品质的影响

通过对馒头采用自然冷却、冷风冷却和真空冷却3种冷却方法,并在4℃的条件下对产品进行贮藏,研究面食品质的变化。结果表明,相对于其他冷却方法,真空冷却将馒头从85℃冷却至20℃所用时间最短,仅为900s,冷却速率高,产品质量损失大,失重率可达到1.683%;冷却后产品硬度、黏性、咀嚼性较大,但粘结性和回弹性方面3种冷却方式没有明显差异;亮度L*偏小,红度a*偏大,黄度b*差异不明显。真空冷却能够有效抑制微生物生长,从而延长食品的保存期。     

真空冷却协同减菌处理对卤牛肉保鲜的影响

为提高酱卤肉制品的品质和安全,延长其货架期,采用单因素实验、对比实验、保质期验证等方法,研究了真空冷却、减菌处理对卤牛肉保鲜的影响。结果表明,真空冷却终温12℃、压力1 200 Pa时,对卤牛肉有很好的保鲜作用,对质构亦无明显不利影响。与对照组相比,实验组的菌落总数、挥发性盐基氮均减少了约2/3,硫代巴比妥酸值(Thiobarbituric Acid Reactive Substances,TBARS)值降低了近1/2。真空冷却结合减菌处理,可显著提高产品的货架期,货架期为:20℃37 d,4℃164 d。该研究可为酱卤肉制品保鲜提供借鉴。     

不同冷却方式对熟制馄饨品质的影响

通过真空冷却、鼓风冷却以及自然冷却3种方式对熟制馄饨进行冷却处理,并在4℃的条件下对产品密封储藏,研究随储存时间的延长,3种不同冷却方式处理的馄饨产品品质的变化情况。结果表明:与常规冷却方式相比较,真空冷却的冷却速率高(P<0.05),冷却失重率大(P<0.05);真空冷却的产品L*值偏小,a*值偏大(P<0.05);硬度和咀嚼性较大、弹性较低(P<0.05),但粘结性、黏性、回复性方面3种冷却方式没有显著差异。随着储藏时间的延长,真空冷却能显著降低馄饨产品的菌落总数、TBA值和pH值(P<0.05),减缓产品品质的劣变。     

真空冷却与常规冷却方式对白煮牛肉品质影响的比较

本实验研究了真空冷却方式与冷风冷却,自然冷却方式对白煮牛肉品质的影响。样品中心温度从80℃冷却到10℃以下,与冷风冷却(120min)室温冷却(240min)相比较,真空冷却(24min)冷却速率较高。与常规冷却方式相比较,真空冷却的冷却损失较高,剪切力较大,硬度较大,弹性较低,色泽较差。感观分析表明,真空冷却样品总体可接受性不及常规冷却样品。微生物检测表明,真空冷却能显著降低菌落总数,减少细菌增殖,保证样品的卫生质量。     

不同冷却终压对低盐腊肉真空冷却效果的影响及模拟研究

本文以低盐腊肉为原材料,采用热质耦合传递模型,对其真空冷却过程进行模拟计算,探究了冷却终压对腊肉冷却速率和质量损失的影响,并将实验和模拟计算结果进行对比分析。结果表明,在腊肉中心温度从80 ℃降至20 ℃过程中,当冷却终压为100 Pa时,实验测试耗时28 min,质量损失为8.0%,模拟计算耗时25 min,质量损失为8.5%;而在冷却终压为2000 Pa时,实验测试耗时58 min,质量损失为7.0%,模拟计算耗时57 min,质量损失为7.5%。这表明冷却终压降低,冷却耗时明显缩短,且实验与模拟结果基本一致,验证了计算模型的可靠性。同时基于冷却终压对冷却速率和质量损失影响的模拟结果,将冷却终压与冷却耗时以及质量损失的关系进行拟合,结果发现冷却终压与冷却耗时呈指数函数关系,而冷却终压与质量损失呈线性函数关系,这为腊肉的快速降温及贮藏提供了参考。     

熟食豆制品的真空冷却工艺研究

研究真空冷却工艺对熟食豆制品品质的影响,并与传统风冷做比较。对其冷却时间、水分含量、质量损失、感官、质构以及色泽进行研究。实验结果表明,真空冷却条件下,将产品的表面温度和中心温度从90℃冷却到5℃,只需19min,而传统风冷方式在冷却40min 后表面温度降到15℃,中心温度仍为42℃。而在感官评定、质构分析和色泽上,两种冷却方式可以达到相同的效果。     

Effect of Belly Handling (Chilled, Frozen, Prerigor) and Smoking Delay on Regular and Sorbate-Cured Bacon

Bellies from three handling methods; fresh, frozen, or prerigor were cured with either 40 ppm sodium nitrite/0.26% potassium sorbate or 120 ppm sodium nitrite. After pumping, one group of bellies was processed (cooked and smoked) immediately, and the remaining group was held 72 hr before processing. Residual nitrite was significnatly higher in regular cure bacon and in bellies processed immediately. By 28 days after packaging, little difference was seen in residual nitrite as a result of any treatment. Regular bacon and immediate processing resulted in greater nitrosopigment conversion. Prerigor bacon had greater pigment conversion and greater residual NaCl concentrations while fresh and frozen bellies were similar. Nitrosamine levels were not influenced by belly handling variables.     

Processing and Sensory Properties of Round Pork Bacon

Pork bellies were cured and assigned to five treatments (n = 10). Round bacon was prepared from tumbled (T), macerated and tumbled (MT), emulsion-coated and tumbled (ET), or macerated, emulsion-coated and tumbled (MET) bellies and compared to control slab bacon. Treated bellies were rolled longitudinally and stuffed into fibrous casings. Bacons were smoked and cooked to 55°C. Few differences were observed between treatments for visual characteristics (binding, cured color, fat/lean ratio). Control slab bacon had greater (P <0.05) off-flavor intensity than all other treatments and MT had the highest (P <0.05) overall acceptability scores. Control slab bacon had lower slicing yield (P <0.05) than all other treatments.     

Effect of rapid and conventional cooling methods on the quality of cooked ham joints

Three cooling regimes, vacuum (VC), blast (BC) and slow cooling (SC), were compared for their effect on cooling rate, weight loss and quality of large cooked ham joints. Vacuum cooling reduced the cooling rate (70-4°C) significantly (P<0.05) in comparison to the other methods; mean cooling times for cooked hams (5-6 kg) were 1.9 h for VC, 11.7 for BC and 14.3 for SC. However, VC gave an increased chill loss (P<0.05) of ca. 11% compared to ca. 4% for the other methods due to evaporative moisture loss. Sensory panels found that VC hams were tougher and less juicy (P<0.05). Shear force measurements and texture profile analysis also showed the vacuum cooling to have a toughening effect on the cooked ham. While vacuum cooling had an adverse effect on quality and yield, it was the only one that conformed to recent safety guidelines for cooked meat joints of a reduction in temperature to 5°C inside 10 h. The cooling conditions used do not reproduce full-scale industrial practice, however, the effects found serve as an indicator of the potential benefits and drawbacks of vacuum cooling for cooked meat joints.     

Validation of bacon processing conditions to verify control of Clostridium perfringens and Staphylococcus aureus

It is unclear how rapidly meat products, such as bacon, that have been heat treated but not fully cooked should be cooled to prevent the outgrowth of spore-forming bacterial pathogens and limit the growth of vegetative cells. Clostridium perfringens spores and vegetative cells and Staphylococcus aureus cells were inoculated into ground cured pork bellies with and without 1.25% liquid smoke. Bellies were subjected to the thermal profiles of industrial smoking to 48.9 degrees C (120 degrees F) and normal cooling of bacon (3 h) as well as a cooling phase of 15 h until the meat reached 7.2 degrees C (45 degrees F). A laboratory-scale bacon smoking and cooling operation was also performed. Under normal smoking and cooling thermal conditions, growth of C. perfringens in ground pork bellies was <1 log regardless of smoke. Increase of S. aureus was 2.38 log CFU/g but only 0.68 log CFU/g with smoke. When cooling spanned 15 h, both C. perfringens and S. aureus grew by a total of about 4 log. The addition of liquid smoke inhibited C. perfringens, but S. aureus still achieved a 3.97-log increase. Staphylococcal enterotoxins were detected in five of six samples cooled for 15 h without smoke but in none of the six samples of smoked bellies. In laboratory-scale smoking of whole belly pieces, initial C. perfringens populations of 2.23 +/- 0.25 log CFU/g were reduced during smoking to 0.99 +/- 0.50 log CFU/g and were 0.65 +/- 0.21 log CFU/g after 15 h of cooling. Populations of S. aureus were reduced from 2.00 +/- 0.74 to a final concentration of 0.74 +/- 0.53 log CFU/g after cooling. Contrary to findings in the ground pork belly system, the 15-h cooling of whole belly pieces did not permit growth of either pathogen. This study demonstrates that if smoked bacon is cooled from 48.9 to 7.2 degrees C (120 to 45 degrees F) within 15 h, a food safety hazard from either C. perfringens or S. aureus is not likely to occur.     

Hot curing Wiltshire bacon

A process combining multi-needle injection and dry salting of whole baconsides before they have been completely chilled can produce acceptable Wiltshire bacon in only 5 days from slaughter. Eating quality and storage stability of sliced and vacuum packed, hot cured bacon were similar to those of dry salted bacon made from conventionally chilled sides. The yields of hot cured and cold cured raw bacon were similar, but cooking yields of hams were over 3.0% higher with hot curing.
A continuous hot curing process from slaughter, through carcass preparation, multi-needle brine injection, dry salting to chilling could simplify Wiltshire bacon processing. The concept could be particularly useful to a processor lacking the specialized facilities for traditional immersion curing.