两种杀菌条件下蓝莓汁储藏品质变化及动力学研究

为了解经热杀菌和微波杀菌后蓝莓汁在不同储藏温度下品质的变化,采用一级反应动力学模型和Arrhenius经验方程,通过分别将热杀菌和微波杀菌所得的蓝莓汁储藏在不同的温度下,研究了储藏期间热杀菌和微波杀菌所得蓝莓汁中菌落总数、花青素含量、色泽的变化规律,并建立了相关动力学模型。结果表明:在储藏期间热杀菌和微波杀菌蓝莓汁中菌落总数、花青素含量、色泽的变化均符合一级反应动力学模型(R2>0.9),并可用Arrhenius方程拟合(R2>0.98);在较低的储藏温度下,蓝莓汁的菌落总数增长缓慢,花青素和色泽的损失较小,蓝莓汁可长时间保持较好的品质;相比热杀菌,微波杀菌能使储藏期间的蓝莓汁更好地保留花青素和色泽,但其保存期相对较短;各模型预测值与实验值之间相对误差均不超过2%,所有模型的预测准确性均较高。     

Effect of pH on Enzyme Inactivation Kinetics in High-Pressure Processed Pineapple (Ananas comosus L.) Puree Using Response Surface Methodology

Effect of pH and high-pressure process treatments viz. pressure, temperature, and dwell time on inactivation of polyphenoloxidase (PPO), peroxidase (POD), bromelain (BRM), and pectinmethylesterase (PME) in pineapple puree was studied. Experiments were conducted according to rotatable central composite design (RCCD) within the range (?α to?+?α) of 100–600 MPa, 20–70 °C, and 0–30 min at three different pH levels (3.0, 3.5, and 4.0) followed by analysis through response surface methodology (RSM). Enzyme inactivation was significantly (p?k in min^?1) revealed that PPO was the most resistive (k ranged between 0.0020 and 0.0379 min^?1) when compared with other three enzymes within the experimental domain. Increased k at lower pH with constant pressure and temperature depicted that pH had negative effect on the inactivation process. The optimized conditions targeting maximum inactivation of PPO, POD and PME with simultaneous retention of BRM in pineapple puree, were 600 MPa/60 °C/9 min, 600 MPa/60 °C/10 min and 600 MPa/60 °C/10 min for the samples of pH 3.0, 3.5, and 4.0, respectively.     

荞麦贮藏过程中的品质变化

综述了贮藏和制粉过程中荞麦色泽和风味的变化,探讨了其影响因子和作用机制,并提出了品质控制方法。     

Changes in Germination and Malting Quality During Storage of Barley

To increase brewing yield and efficiency, malts with high extract values, high enzymic activities and good modification are essential. To produce malt that meets these requirements, the barley employed must have minimal post‐harvest dormancy and be able to germinate vigorously. The aims of this study were to determine the extent to which some Australian barley varieties changed during post‐harvest storage, how these changes influenced germination characteristics, enzyme production and malt quality, and, of the germination tests examined, which gave the best indication of a barley's malting potential. Four commercially grown barley samples were obtained, one from Tasmania and three from Victoria. Each sample was stored at room temperature for one year. At monthly intervals, samples were taken and placed at ?18°C. The germinative energy (GE) and germinative index (GI) of these samples were measured. Samples were also micro‐malted and the quality of the malt was assessed using standard EBC methodology. Storage at room temperature positively influenced the germination characteristics of all samples, with concomitant improvements in hydrolytic enzyme production during malting and in a number of malt quality parameters. It was found that, of the germination tests examined, the GI consistently correlated with enzyme activities during malting and with various malt quality parameters thus indicating that the GI is a good indicator of malting potential.     

Effects of Gellan-Based Edible Coating on the Quality of Fresh-Cut Pineapple During Cold Storage

The effects of gellan-based [gellan gum 0.56 % (w/v), glycerol 0.89 % (w/v) and sunflower oil 0.025 % (w/v)] edible coating on the respiration rate, physico-chemical properties and microbiological and sensory quality of fresh-cut pineapple during 16 days of storage (5?±?1 °C, 85?±?10 % RH) were evaluated. Uncoated fresh-cut pineapple was stored under the same condition and served as the control. For cross-linking reaction which was necessary for gel formation of gellan gum, a 2 % (w/v) calcium chloride solution that contained 1 % (w/v) ascorbic acid and 1 % (w/v) citric acid (as antibrowning agents) was used. The results obtained show that the respiration rate and weight loss of gellan-based coated samples were significantly (p?<?0.05) lower than those of the uncoated samples during 16 days of storage at 5 °C. In addition, coated samples significantly (p?<?0.05) maintained the firmness and colour of fresh-cut pineapple during low-temperature storage as compared to uncoated samples. The results obtained in this study also indicate that pH, titratable acidity and total soluble solids of coated and uncoated samples showed little changes during 16 days of storage at 5 °C. Gellan-based formulation did not show any antimicrobial effect, and no significant (p?>?0.05) differences were found among total plate counts and yeast and mould counts for coated and uncoated samples. Total plate counts and yeast and mould counts for coated and uncoated samples reached 10⁶ CFU/g (limit of shelf life acceptance for fruit-based products recommended by the Institute of Food Science and Technology in the UK) after 12 days of storage at 5 °C. In addition, the scores for all sensory characteristics at day 12 were significantly (p?<?0.05) higher in coated samples as compared to control. Therefore, the results obtained in this study indicate that gellan-based edible coating formulation has the potential to maintain the quality of fresh-cut pineapple during low-temperature storage for about 12 days.     

Non-Volatile Organic Acids,pH and Titratable Acidity Changes in Pineapple Fruit Slices During Frozen Storage

Effects of freezing and frozen storage on pH, titratable acidity and non-volatile organic acids of two pineapple fruit cultivars, Smooth Cayenne and Red Spanish, were studied. Pineapple fruit was frozen as slices in a cold room at −18°C and stored at this temperature for a 12 month period. A negative correlation was found between pH and titratable acidity in the two cultivars throughout frozen storage ( r =-0·67 for Smooth Cayenne and r =-0·71 for Red Spanish). Non-volatile organic acids were determined by high performance liquid chromatography. The major components were citric and L-malic acids. A high correlation was found between these two acids during frozen storage ( r =0·75 in Smooth Cayenne and r =0·78 in Red Spanish). There were significant differences ( P⩽ 0·01) in pH and titratable acidity between the two studied varieties after a year of frozen storage. Significant differences ( P⩽ 0·05) were found in pH values during frozen storage in cv Smooth Cayenne and in citric and L-malic acids in cv Red Spanish. Freezing preservation of pineapple fruit slices led to minimal chemical changes after a year of frozen storage.     

Quality Changes in Unsulfured Sun Dried Apricots During Storage

The sun dried apricots (Hacihaliloglu) from Malatya region of Turkey without sulfur dioxide application packaged in polyvinyl chloride laminated with polyethylene bags of different thickness under normal and modified atmosphere were stored at 5 ± 1, 15 ± 1, and 25 ± 1°C, respectively. The changes in quality characteristics of dried apricots were investigated by using objective and sensory methods of evaluation during a storage period of 48 weeks. The study showed that the unsulfured sun dried apricots have a storage life of up to 30 weeks provided that they are packaged under modified atmosphere and stored at 5 ± 1°C after processing.     

Quality of Banana Puree During Storage: a Comparison of High Pressure Processing and Thermal Pasteurization Methods

The quality features of banana puree after high pressure processing (HPP) at 500 MPa for 10 min and thermal pasteurization (TP) at 90 °C for 2 min during 30 days of refrigerated storage were compared in this study. Initial counts in banana puree of greater than 3.80 log colony-forming units (CFU)/g of total aerobic bacteria (TAB) and 3.10 log CFU/g of molds and yeasts (M&Y) were reduced by HPP and TP. TAB were approximately 1.0 CFU/g, and M&Y were less than 0.3 log CFU/g in HPP- and TP-processed puree during storage. HPP and TP did not change pH, titratable acidity (TA), total soluble solids (TSS), lightness (L), and yellowness (b), total phenolic content (TPC), and antioxidant capacity (AC), but HPP raised redness (a) and TP reduced a and ascorbic acid (AA). During storage, L, a, and b in HPP- and TP-processed purees did not change but HPP-processed puree increased pH and decreased TA. After storage, the percentage of TPC and AA was 75.85 and 55.09 % in the HPP group and 96.30 and 68.09 % in the TP group, indicating a significant loss of TPC and a greater loss of AA in HPP-processed puree. The loss of AC agreed with the loss of AA and TPC. HPP preserved particle size distribution and viscosity of purees, whereas TP increased the number of smaller particles and viscosity after processing and in storage. Twenty-six volatiles (18 esters) and 22 volatiles (15 esters) were detected in HPP- and TP-processed purees, and the ester fraction was 69.79 and 52.36 %, respectively. HPP was found to be an effective alternative pasteurization method for preserving the quality of fresh banana puree.     

Chemical and Physico-chemical Changes in Processed Cheese and Ready-made Fondue During Storage. A Review

Processed cheese is often expected to be a stable product with a very long shelf-life. However, even products without any bacteriological contamination retain their high quality only for a few months at room temperature. During storage, structure and flavour slowly change. The following possible causes for such changes are reviewed in the present paper: loss of water vapour, hydrolysis of polyphosphates, changes in ionic equilibria, crystal formation, oxidation, nonenzymic browning, enzymatic activity as well as interactions with packaging materials. The changes with age of processed cheese are influenced by four main factors: product composition, processing, packaging and storage conditions (time and temperature). No work about the changes with age of ready-made fondue appears to have been published.     

Evolution of Quality Characteristics of Minimally Processed Asparagus During Storage in Different Lighting Conditions

ABSTRACT:  The effect of different types of lighting (white, green, red, and blue light) on minimally processed asparagus during storage at 4 °C was studied. The gas concentrations in the packages, pH, mesophilic counts, and weight loss were also determined. Lighting caused an increase in physiological activity. Asparagus stored under lighting achieved atmospheres with higher CO₂ and lower O₂ content than samples kept in the dark. This activity increase explains the greater deterioration experienced by samples stored under lighting, which clearly affected texture and especially color, accelerating the appearance of greenish hues in the tips and reddish-brown hues in the spears. Exposure to light had a negative effect on the quality parameters of the asparagus and it caused a significant reduction in shelf life. Hence, the 11 d shelf life of samples kept in the dark was reduced to only 3 d in samples kept under red and green light, and to 7 d in those kept under white and blue light. However, quality indicators such as the color of the tips and texture showed significantly better behavior under blue light than with white light, which allows us to state that it is better to use this type of light or blue-tinted packaging film for the display of minimally processed asparagus to consumers.     

小麦粉储藏品质变化规律研究

本文研究了不同类型的小麦粉样品在38℃和70％相对湿度的密闭条件下储藏过程中品质的变化规律，结果表明：储藏2个星期之后，样品的淀粉酶活性急剧下降；面筋的含量和质量以及面团的流变学特性均呈现出一定的规律性变化。包括面筋吸水量下降；面团粉质吸水率增加；吹泡P值增大，L值减小，P／L值增大；RVA特征粘度值增大。其中，吹泡曲线的特征值变化最为明显。但是这些指标的变化与原料小麦粉的质量有很大的关系，因储藏而造成的品质差异无法超越样品间原有的品质差别。馒头品质随储藏时间的延长而变劣，但这种变化的速度在不同的样品间存在差异，原因尚需要进一步探索。     

Microbial, Enzymatic, and Chemical Changes During Storage of Fresh and Processed Orange Juice

Microbial, enzymatic, and chemical comparisons were made on orange juice stored at 4°C without pasteurization, with light pasteurization (66°C, 10 sec) directed at vegetative microorganisms, and with full pasteurization (90°C, 60 sec) directed at the heat stable isozyme of pectinesterase. Effects of oxygen-barrier and nonbarrier packaging were also examined. Oxygen-barrier packaging did not benefit unpasteurized juice. However, lightly and fully pasteurized juices in barrier cartons exhibited lower microbial counts, greater ascorbic acid retention, and apparent slowing of cloud loss by the third week of storage. During the first 22 days storage, microbial, cloud, sugar, and ascorbic acid values for lightly pasteurized juice were similar to those of juice receiving full pasteurization.     

大曲在贮存过程中质量变化的研究

介绍了大曲在贮存过程中感官质量和理化指标变化情况。大曲在贮存过程中降幅最大的是发酵力,而大曲发酵力的高低对入窖米查醅的发酵质量起着决定性的作用,如果用刚出房的新曲或贮存时间较短的大曲与陈曲混合来提升大曲的发酵力,会增加酒体的刺激感和酒体杂味,造成酒体口感质量的下降;大曲贮存时间以不低于6个月为宜。     

冷冻肉品储藏期间品质变化及控制措施(英文)

The frozen is a common method of meat storage,generally applications in meat industrial.However,the quality of meat still have taken place changes even in the low temperature,This article discussion on the changes of frozen meat quality during freezing storage,and give the corresponding control measures.     

冷冻肉品储藏期间品质变化及控制措施

冷藏是常用的肉品储藏方法,工业化应用普遍,但在储藏中肉的品质也发生相应的变化,文章就肉品冷藏期间发生的各种变化进行了论述,并提出相应的控制措施。     

超高温灭菌乳在贮藏过程中的质量变化

对经超高温灭菌乳在贮存过程中发生的一些感官、理化、微生物的变化进行了观测，并根据结果来探讨延长超高温灭菌牛乳保质的方法。分析了引起这些变化的原因并提出了一些控制措施。     

冷却牛肉贮藏过程中的品质变化

分析冷却牛肉贮藏过程中各品质指标的变化,确定理化指标和微生物指标的相关性,为提高牛肉的品质提供依据。文中测定了4℃贮藏的冷却牛肉在0、2、4、6、8、10、12、14 d的菌落总数、嗜冷菌总数、pH值、挥发性盐基氮、失水率、色差值,确定了各指标随保存时间的变化规律及其相关性。结果表明:在贮藏过程中,pH值呈现先下降后上升的趋势;挥发性盐基氮呈上升趋势;系水力逐渐下降;肉色a值、DE(d ifference error)值不断降低。在品质变化的各指标中,微生物菌落总数、嗜冷菌总数与pH值呈正相关,且差异显著(P<0.05);菌落总数与系水力、a值呈负相关性,差异显著(P<0.05)。其中菌落总数与挥发性盐基氮、a值的相关性较大且极显著相关(P<0.01)。由此可知,微生物的活动能引起牛肉理化指标的变化,通过测定挥发性盐基氮和a值可以客观反映冷却牛肉的微生物污染状况。