贮存过程中添加剂对浓缩苹果汁非酶褐变的影响

贮存过程中添加剂对浓缩苹果汁非酶褐变的影响很大。Cys浓度降低。苹果汁的非酶褐变加重：Fe^3 、Fe^2 、Cu^2 均会促进非酶褐变反应速率。     

我国外来入侵种福寿螺分子生物学研究进展

福寿螺是一类恶性外来入侵生物,自20世纪80年代初引种并入侵我国以来,对我国农作物生产和水生生态系统造成了严重的危害.我国已报道的福寿螺入侵种类包括Pomacea canaliculata和P.insularum两种,这两种福寿螺也是东南亚、南亚和北美等多国的入侵种类.这两种福寿螺近年来在世界范围内得到了广泛的研究,现综述这两种福寿螺分子生物学的研究进展,包括种类的分子鉴定、分子系统学及蛋白基因的研究等,并对其分子生物学研究和应用进行了讨论和展望.     

Antimicrobial edible apple films inactivate antibiotic resistant and susceptible Campylobacter jejuni strains on chicken breast

Abstract: Campylobacter jejuni is the leading cause of bacterial diarrheal illness worldwide. Many strains are now becoming multidrug resistant. Apple‐based edible films containing carvacrol and cinnamaldehyde were evaluated for bactericidal activity against antibiotic resistant and susceptible C. jejuni strains on chicken. Retail chicken breast samples inoculated with D28a and H2a (resistant strains) and A24a (a sensitive strain) were wrapped in apple films containing cinnamaldehyde or carvacrol at 0.5%, 1.5%, and 3% concentrations, and then incubated at 4 or 23 °C for 72 h. Immediately after wrapping and at 72 h, samples were plated for enumeration of viable C. jejuni. The antimicrobial films exhibited dose‐ and temperature‐dependent bactericidal activity against all strains. Films with ≥1.5% cinnamaldehyde reduced populations of all strains to below detection at 23 °C at 72 h. At 4 °C with cinnamaldehyde, reductions were variable for all strains, ranging from 0.2 to 2.5 logs and 1.8 to 6.0 logs at 1.5% and 3.0%, respectively. Films with 3% carvacrol reduced populations of A24a and H2a to below detection, and D28a by 2.4 logs at 23 °C and 72 h. A 0.5‐log reduction was observed for both A24a and D28a, and 0.9 logs for H2a at 4 °C at 3% carvacrol. Reductions ranged from 1.1 to 1.9 logs and 0.4 to 1.2 logs with 1.5% and 0.5% carvacrol at 23 °C, respectively. The films with cinnamaldehyde were more effective than carvacrol films. Reductions at 23 °C were greater than those at 4 °C. Our results showed that antimicrobial apple films have the potential to reduce C. jejuni on chicken and therefore, the risk of campylobacteriosis. Possible mechanisms of antimicrobial effects are discussed. Practical Application: Apple antimicrobial films could potentially be used in retail food packaging to reduce C. jejuni commonly present on food.     

沼液对苹果品质及土壤肥效的影响

通过对照试验，分析了沼肥对果树长势、苹果品质和土壤肥效的影响。结果表明，应用沼液进行根施和叶面喷施，可增加果树新梢长度和枝条径粗，果树总产量增加13％～20％，果实口感好，营养丰富。施用沼肥可改善土壤理化性质，氮、磷、钾处于丰富的水平，有机质处于中等至稍丰的水平。     

Influence of Texture on Taste: Insights Gained During Studies of Hardness, Juiciness, and Sweetness of Apple Fruit

Apple flesh can be considered as a living structure within which juice and tastants are encapsulated in individual cells. The breakdown of this structure and release of juice varies between hard and soft apples. We hypothesized that the texture of the fruit and the way it releases juice during chewing would therefore influence the perception of sweetness. Time‐intensity (TI) techniques were used by a trained panel to study the temporal changes in the intensity of “juiciness” and “sweetness” during consumption of apples that varied in mechanical hardness (measured by puncture test). All apple samples had a similar water content, but the pattern of juice release was markedly different. Juice was released into the mouth in a pattern of increasing and then deceasing intensity. The maximum intensity (Imax), duration of the stimulus (DUR), and area under the TI curve (AUC) were significantly higher for hard compared with soft apples. The impact of juice release on perception of sweetness was examined using apples in which the Imax and AUC for juiciness of soft apples were half the value of those for firm apples. There was no consistent difference in Imax, DUR, or AUC for sweet taste in these 2 sets of apples. We concluded that sufficient juice was released from soft and less juicy apples to ensure that sweetness perception was maximized. These results are discussed in relation to earlier studies that demonstrated that texture (thickening agents) suppresses flavor perception in solutions and juices.     

苹果酱加工中褐变利用研究与探讨

根据苹果果肉在加工中褐变程度不同,其色泽不同的现象,研究了利用褐变对苹果酱加工色泽控制的新方法,探讨了利用酶褐变与色泽变化规律进行水果蔬菜加工色泽控制的途径,为果蔬加工品的色泽控制提供了全新的思路与可行的研究方法。     

Cell Wall Stability of Fresh-Cut Fuji Apples Treated with Calcium Lactate

ABSTRACT:  This article studies the effect of calcium lactate on the structure (using low-temperature scanning electron microscopy, transmission electron microscopy, and light microscopy), texture (penetration test), pectinmethylesterase activity (titration of free carboxylic groups released by the enzyme), and polygalacturonase activity (viscosimetry) on fresh-cut Fuji apples stored for 3 wk at 4 °C. The results show that calcium lactate strengthens the structure of fresh-cut Fuji apple cell walls and counteracts the increased activity of both the pectinmethylesterase and polygalacturonase enzymes. Therefore, it is advisable to treat the product with calcium lactate to improve its structural stability. At a macroscopic level, this calcium treatment maintains the texture for at least 3 wk of storage at 4 °C.     

Characterization of Apples and Apple Cider Produced by a Guelph Area Orchard

Thermal stability of food-borne pathogens in apple cider is influenced by the composition of the product. As a preliminary step to determining the effect of pasteurization of apple cider on survival of E. coli O157:H7, a study was carried out to characterize apples and unpasteurized apple cider produced by a guelph area orchard. Samples of commercial unpasteurized cider and the constituent apples were collected over 13 wk from August to November 1998, and unpasteurized laboratory cider was made from the individual apple varieties. pH, titratable acidity (TA), turbidity, total microbial counts, total solids and °brix for filtered and unfiltered samples were measured. The maximum, minimum, and average values for all unpasteurized commercial cider samples were found to be: pH, 3.71, 3.17, and 3.43; TA, 93.47, 49.46, and 69.95 mL of 0.1 N NaOH/100 mL; total solids, 13.21, 10.93, and 11.90%; °brix, 13.01, 11.17, and 12.02; turbidity, 238.1, 145.1, and 204.9 NTU; and total plate count, 4.91, 2.61, 3.75 log cfu·mL⁻¹. There were no significnat differences (P>0.05) between filtered and unfiltered samples. In addition, in commercial unpasteurized cider, there were no significant differences (P>0.05) with respect to any of the factors with time of processing. The composition of the unpasteurized laboratory cider made form individual apple varieties was dependent on the variety, but was generally within the ranges from published literature values. Mclntosh apples showed a significant (P≤0.05) decrease in TA with time of harvest. The results suggest that it is necessary to take the composition of commercial apple cider into account when developing thermal inactivation models for food-borne pathogens.     

采后热处理对红富士苹果青霉病和灰霉病的控制

热空气处理能有效抑制灰葡萄孢(Botrytiscinerea)和扩展青霉(Penicilliumexpansum)的毒性。灰葡萄孢比扩展青霉的热敏感度高,Bcinerea孢子38℃热处理48h即能完全抑制孢子萌发。热处理72h的Bcinerea平板均无菌丝生长。Pexpansum的孢子活性和菌丝生长随热处理时间的延长而明显减缓。热处理后的霉菌孢子在苹果果实内生长缓慢,Bcinerea孢子在热处理72h后在苹果中的生长完全受抑制,腐烂发生率为零。Pexpansum热处理72h后才能显著抑制苹果的腐烂发生。苹果接种霉菌后再进行热处理(38℃,96h),无论是0℃还是20℃下放置,均未发现腐烂,大大减少贮期灰霉病、青霉病的发生。研究还发现,经过2个月冷藏后,与对照组相比,热处理过的红富士苹果果皮色泽更黄,糖酸比上升,呼吸强度较低,硬度保持较好,说明热处理能够正面影响苹果的贮藏品质。     

HACCP在浓缩苹果汁生产中的应用

根据HACCP的具体要求和生产过程中的实际情况,详细阐述了HACCP在浓缩苹果汁中的实施方案。