Inactivation of spoilage microorganisms in apple cider using a continuous flow pulsed electric field system

The effect of pulsed electric field (PEF) in inactivating naturally occurring microorganisms (yeast and molds) in freshly squeezed apple cider was investigated in a continuous flow system. The microbial count decreased with an increase of applied pulses (17.6-58.7 total) and treatment temperature (45-50 °C), and a decrease of flow rate (3-10 l/h). At field strength of 27-33 kV/cm (3 mm electrode gap in a concentric chamber), 200 pulses/s, 3 l/h flow rate, and 50 °C process temperature, there was a 3.10 log reduction in microbial counts. By PEF treatment in the presence of a mixture of nisin and lysozyme (27.5 U/ml for nisin and 690 U/ml for lysozyme), there was an increase in the microbial count from 1.12 to 1.78 log reductions for 10 l/h flow. When cider samples were treated in the presence of clove oil (3 or 5 ml/100 ml), an additive reduction of 1.99 log cycles in microbial counts was observed.     

Power ultrasound treatment of Listeria monocytogenes in apple cider

Inactivation experiments with Listeria monocytogenes 10403S, an ultrasound-resistant strain, were conducted at sublethal (20, 30, and 40 degrees C) and lethal (50, 55, and 60 degrees C) temperatures in saline solution (pH 7.0), acidified saline solution (pH 3.4), and apple cider (pH 3.4) with and without application of ultrasound (20 kHz, 457 mW.ml(-l)). The survival of recoverable L. monocytogenes 10403S in apple cider was evaluated, and the effects of temperature, ultrasound, pH, and food matrix on inactivation were studied. Application of ultrasound increased the inactivation rate at both sublethal and lethal temperatures. Additional death of L. monocytogenes 10403S was due to low acidity at the lethal temperatures. The reduction in surviving L. monocytogenes 10403S followed first order kinetics at sublethal temperatures, but at lethal temperatures, a two-section linear model described the inactivation behavior. The bactericidal effect of thermosonication was additive in apple cider. The survival tests of L. monocytogenes 10403S in apple cider indicated the possibility of using a mild treatment condition in combination with ultrasound to achieve a 5-log reduction in number of listerial cells.     

Inactivation of Escherichia coli O157:H7 and other naturally occurring microorganisms in apple cider by electron beam irradiation

Two Escherichia coli O157:H7 strains, SEA 13 B88 gfp 73ec and B6-914 gfp 90ec, together with two bacteria, three yeasts, and two molds that were randomly selected from a collection of microorganisms found on apples or in apple cider, were inoculated into apple cider and subjected to electron beam irradiation at several doses between 0.0 and 2.3 kGy at the Iowa State University Linear Accelerator Facility. The D-values for the E. coli O157:H7 strains ranged between 0.25 and 0.34 kGy; the D-values for most of the normal flora from apples ranged between 0.24 and 0.59 kGy. By taking into account possible variations in treatment conditions, it was calculated that irradiation at 2.47 kGy should achieve a 5-log reduction of E. coli O157:H7 in apple cider at the 95% confidence level. Naturally occurring yeasts might survive such irradiation treatment.     

Inactivation of Escherichia coli (ATCC 4157) in diluted apple cider by dense-phase carbon dioxide

Dense-phase carbon dioxide (CO2) treatments in a continuous flow through system were applied to apple cider to inactivate Escherichia coli (ATCC 4157). A response surface design with factors of the CO2/product ratio (0, 70, and 140 g/kg), temperature (25, 35, and 45 degrees C), and pressure (6.9, 27.6, and 48.3 MPa) were used. E. coli was very sensitive to dense CO2 treatment, with a more than 6-log reduction in treatments containing 70 and 140 g/kg CO2, irrespective of temperature and pressure. The CO2/product ratio was the most important factor affecting inactivation rate of E. coli. No effect of temperature and pressure was detected because of high sensitivity of the cells to dense CO2. Dense CO2 could be an alternative pasteurization treatment for apple cider. Further studies dealing with the organoleptic quality of the product are needed.     

UV inactivation of bacteria in apple cider

Apple cider, inoculated with Escherichia coli and Listeria innocua, was processed using a simple UV apparatus. The apparatus consisted of a low-pressure mercury lamp surrounded by a coil of UV transparent tubing. Cider was pumped through the tubing at flow rates of 27 to 83 ml/min. The population of E. coli K-12 was reduced by 3.4 +/- 0.3 log after being exposed for 19 s at a treatment temperature of 25 degrees C. The population of L. innocua, which was more resistant to UV, was reduced by 2.5 +/- 0.1 log after being exposed for 58 s. The electrical energy for the process was 34 J/ml and is similar to that for conventional thermal processing. UV processing has the potential to improve the safety and extend the shelf life of apple cider.     

苹果酒香气成分研究进展

苹果酒的香气成分是构成苹果酒质量的重要因素,决定着苹果酒的风味和典型性.文中综述了苹果酒中主要的香气成分及其来源,并介绍了国内外苹果酒中香气成分的提取和分析方法.     

苹果酒醋饮料的生产工艺

介绍了采用浓缩苹果汁发酵成苹果酒后,再经沈麦112-7#醋酸菌发酵,所得酒醋混合母液与木糖醇、低聚异麦芽糖、维生素C等辅助成分进行科学调配生产苹果醋醋饮料的工艺流程.     

苹果酒发酵工艺对比研究

利用德国生产的5L全自动发酵罐和0.5L三角瓶,以5个栽培苹果品种的果实(‘鲁加1号’、‘鲁加4号’、‘鲁加5号’、‘国光’、‘新红星’)为原料,发酵温度设定为20℃,酵母菌接种量为5%,进行苹果酒发酵工艺初步的放大试验。测定5个品种在陈酿过程中的酒精度、单宁、总酚、可滴定酸、透光率、可溶性固形物变化情况。结果表明,当发酵体积扩大10倍后,发酵罐中苹果酒发酵效果与三角瓶中小体积状态下的发酵效果无显著差异,总的变化趋势趋于一致。     

苹果醋肽饮料的研制

介绍了以苹果醋为主要载体并配以一定数量的大豆多肽．然后与苹果汁、蜂蜜、低聚异麦芽糖、维生素B族、维生素C、果溶Ca等辅助成分进行科学调配生产苹果醋肽饮料的工艺流程．     

苹果醋的开发与研究综述

回顾了苹果醋的历史和现状,对苹果醋的功能、发酵机理、风味、酿造工艺、种类和研究现状进行总结,对苹果醋的发展意义和趋势进行了讨论,并展望了苹果醋的发展前景.充分利用苹果资源进行果醋产品的开发与生产,可为苹果的深加工及综合利用创造有效途径.     

Microbial levels in Michigan apple cider and their association with manufacturing practices

In recent decades, apple cider has been implicated in a series of outbreaks of foodborne illness. The objective of this study was to determine the presence and concentrations of pathogenic and indicator microorganisms in apple cider processed in Michigan and to evaluate the impact of thermal pasteurization, UV light radiation, and implementation of hazard analysis critical control point (HACCP) plans on these microbes. Cider samples were obtained from Michigan mills between 1997 and 2004 and analyzed for Escherichia coli O157:H7, Salmonella, generic E. coli, total coliforms, and aerobic bacteria. Neither E. coli O157:H7 nor Salmonella were detected in any tested cider samples, suggesting a very low frequency of pathogens in Michigan apple cider. The persistent and relatively high frequency of generic E. coli observed in samples obtained in all years indicates a continued risk of pathogen contamination in Michigan apple cider, especially when it is untreated. The use of thermal pasteurization or UV light radiation and reported implementation of HACCP plans were associated with lower frequency and counts of generic E. coli, total coliforms, and aerobic microorganisms. However, the relatively high counts of indicator organisms in some cider samples that were claimed to be treated according to these pathogen reduction measures indicates that some processors had inadequate practices, facilities, or equipment for pathogen reduction or did not consistently or adequately apply practices or pathogen-reduction equipment in an effective manner.     

Potential sources of microbial contamination in unpasteurized apple cider

A study was conducted to identify possible sources of microbial contamination and to assess the effect of good cleaning and sanitation practices on the microbial quality and safety of unpasteurized apple cider. Raw unwashed apples, washed apples, cleaning water, fresh cider, and finished cider samples were collected from five Ontario producers over 4 months and microbiologically tested. Total coliforms were found in 31, 71 and 38% of the unwashed apple, water, and washed apple samples, respectively. Escherichia coli was found in 40% of the water samples from one producer alone. The washing step was identified as a potential source of contamination, possibly due to water in the dump tanks seldom being refreshed, and because scrubbers, spray nozzles, and conveyors were not properly cleaned and sanitized. Higher total coliform counts (P < 0.0001) and prevalence (P < 0.0001) in fresh cider compared with those in unwashed apples and washed apples indicated considerable microbial buildup along the process, possibly explained by the lack of appropriate equipment sanitation procedures. Results showed that producers who had better sanitary practices in place had lower (P < 0.001) total coliform prevalence than the rest of the producers. Overall results show that good sanitation procedures are associated with improved microbial quality of fresh cider in terms of total coliforms and that operators who pasteurize and/or UV treat their product should still be required to have a sound good manufacturing practices program in place to prevent recontamination. Cryptosporidium parvum, an important pathogen for this industry, was found in different sample types, including washed apples, water, and fresh and finished cider.     

苹果醋饮料的研制与生产

该技术以辽南优质苹果为主要原料,采用液态发酵法生产工艺,经酒精发酵、醋酸发酵制成果香味浓郁的苹果醋,最后再经调配制成高级营养保健饮品。     

Rheological and technological properties of two cider apple cultivars

Two cider apple cultivars (Avrolles and Douce Coetligné) were compared for their technological and rheological properties and the evolution of these properties during storage after harvest (15 or 30 days). Avrolles was characterized by high and stable juice yields whereas Douce Coetligné had a lower juice yield at harvest which further decreased during storage. The aim was to identify measures of fruit texture which might be related to the fruits behaviour during pressing. Force-displacement curves were computed during penetrometric and compressive tests performed on a TAXT2 texturometer on 20 fruits sampled at three dates. Two main rheological factors have been pointed out. First, under strain, Avrolles showed important plastic irreversible deformations with important breakdowns of cells layers whereas visco-elastic mechanisms appeared more important for Douce Coetligné. Secondly, for this last cultivar, during storagethe skin seemed to act increasingly as a protection against initiation and propagation of cells fractures inside the inner tissues.     

The neutral volatile components of cider apple juices

Examination of the volatile compounds from juices of four cultivars of cider apple (‘Bramley's Seedling’, ‘Sweet Coppin’, ‘Kingston Black’ and ‘Yarlington Mill’) has led to the definite identification of eighteen alcohols, forty-eight esters, five carbonyls, eight acetals, four ethers, one lactone, one hydrocarbon and three halogenated compounds, tentative evidence being presented for a further 51 components. Fifty-five of the reported compounds have not previously been found in whole apples or juices. Of these cis and trans linalool oxide and the presence of 5-hexen-1-ol, rather than 2-hexen-1-ol, in the juice of the cultivar ‘Kingston Black’, are of particular interest. Differences between cultivars were largely quantitative and due to variations in the amounts of components with boiling points in excess of that of hexanol.     

果肉型苹果醋酿造工艺的研究

探索了以鲜苹果为原料加工制成苹果浆,经过酒精发酵和醋酸发酵酿制苹果醋的新工艺,分析了苹果醋的加工工艺和操作要点。     

Isolation and characterization of Escherichia coli recovered from Maryland apple cider and the cider production environment

Contaminated apple cider has been implicated in several Escherichia coli O157:H7 outbreaks. In an attempt to investigate sources and modes of entry of E. coli into apple cider, samples of fresh apple, pomace, and cider and equipment and mill floor swabs were analyzed for standard plate counts (SPC), total coliforms (TC), fecal coliforms (FC), and E. coli. E. coli was isolated from 14 (33%) of 42 samples of bottled fresh cider, from food equipment in 6 (67%) of 9 mills, and from apples, pomace, or cider in 7 (78%) of 9 mills. Seventy-five E. coli isolates were further characterized for Shiga toxin-producing E. coli (STEC)-associated virulence factors, antimicrobial susceptibility, and pulsed-field gel electrophoresis (PFGE) type. No E. coli O157:H7 or other STEC was identified. Serotyping and PFGE revealed 64 distinct profiles, suggesting that recovered E. coli arose from multiple independent sources. However, on one occasion, E. coli isolated from the source apple sample was closely related to the E. coli identified in the finished cider sample. E. coli isolates were further tested for antimicrobial susceptibility to 17 antimicrobial agents of human and veterinary importance. Fourteen (19%) of the 75 isolates were resistant to at least one of the antimicrobial agents tested, and 9 (12%) were resistant to at least two of these agents. Of the resistant isolates recovered, 64% were resistant to tetracycline and 57% were resistant to streptomycin. Overall, the level of E. coli contamination in source apple samples did not differ significantly from those in samples of pomace, cider at the press, and cider entering the bottling tank; therefore, source apples cannot be dismissed as a potential contributor of E. coli to the cider-making process.     

功能性苹果酒酿造工艺研究

以富含超氧化物歧化酶（SOD）的功能性苹果为主要原料酿造苹果酒,采用安琪牌葡萄酒酵母作为菌种,用量为0．5‰;品温控制15℃-22℃,发酵时间16d-20d,酿制出的苹果酒感官、理化指标达到国家相关标准,并且富含SOD及其他多种营养成分,具有延缓衰老、调节免疫等保健功能。     

Inactivation of Cryptosporidium parvum oocysts in cider by flash pasteurization

Cryptosporidium parvum is a well-recognized pathogen of significant medical importance, and cider (apple juice) has been associated with foodborne cryptosporidiosis. This study investigated the effect of flash pasteurization on the viability of contaminant C. parvum oocysts. Cider inoculated with oocysts was heated at 70 or 71.7 degrees C for 5, 10, or 20 s, and oocyst viability was measured by a semiquantitative in vitro infectivity assay. By infecting multiple wells of confluent Madin-Darby bovine kidney cells with serial dilutions of heat-treated oocysts and examining infected cells by indirect fluorescent antibody staining, the most probable number technique was applied to quantify log reduction of oocyst viability. Heating for 10 or 20 s at either temperature caused oocyst killing of at least 4.9 log (or 99.999%), whereas oocyst inactivation after pasteurization for 5 s at 70 and 71.7 degrees C was 3.0 log (99.9%) and 4.8 log (99.998%), respectively. Our results suggested that current practices of flash pasteurization in the juice industry are sufficient in inactivating contaminant oocysts.