Influence of fruit variety, harvest technique, quality sorting, and storage on the native microflora of unpasteurized apple cider

Apple variety, harvest, quality sorting, and storage practices were assessed to determine their impact on the microflora of unpasteurized cider. Seven apple varieties were harvested from the tree or the ground. The apples were used fresh or were stored at 0 to 4 degrees C for < or = 5 months and were pressed with or without quality selection. Cider yield, pH, Brix value, and titratable acidity were measured. Apples, postpressing apple pomace, and cider samples were analyzed for aerobic bacteria, yeasts, and molds. Aerobic bacterial plate counts (APCs) of ciders from fresh ground-picked apples (4.89 log CFU/ml) were higher than those of ciders made from fresh, tree-picked apples (3.45 log CFU/ml). Quality sorting further reduced the average APC to 2.88 log CFU/ml. Differences among all three treatment groups were significant (P < 0.0001). Apple and pomace microbial concentrations revealed harvest and postharvest treatment-dependent differences similar to those found in cider. There were significant differences in APC among apple varieties (P = 0.0001). Lower counts were associated with varieties exhibiting higher Brix values and higher titratable acidity. Differences in APC for stored and fresh apples used for cider production were not significant (P > 0.05). Yeast and mold counts revealed relationships similar to those for APCs. The relationship between initial microbial load found on incoming fruit and final cider microbial population was curvilinear, with the weakest correlations for the lowest apple microflora concentrations. The lack of linearity suggests that processing equipment contributed to cider contamination. Tree-picked quality fruit should be used for unpasteurized cider production, and careful manufacturing practices at cider plants can impact both safety and quality of the final product.     

Apple quality,storage, and washing treatments affect patulin levels in apple cider

Patulin is a mycotoxin produced primarily by Penicillium expansum, a mold responsible for rot in apples and other fruits. The growth of this fungus and the production of patulin are common in fruit that has been damaged. However, patulin can be detected in visibly sound fruit. The purpose of this project was to determine how apple quality, storage, and washing treatments affect patulin levels in apple cider. Patulin was not detected in cider pressed from fresh tree-picked apples (seven cultivars) but was found at levels of 40.2 to 374 microg/liter in cider pressed from four cultivars of fresh ground-harvested (dropped) apples. Patulin was not detected in cider pressed from culled tree-picked apples stored for 4 to 6 weeks at 0 to 2 degrees C but was found at levels of 0.97 to 64.0 microg/liter in cider pressed from unculled fruit stored under the same conditions. Cider from controlled-atmosphere-stored apples that were culled before pressing contained 0 to 15.1 microg of patulin per liter, while cider made from unculled fruit contained 59.9 to 120.5 microg of patulin per liter. The washing of ground-harvested apples before pressing reduced patulin levels in cider by 10 to 100%, depending on the initial patulin levels and the type of wash solution used. These results indicate that patulin is a good indicator of the quality of the apples used to manufacture cider. The avoidance of ground-harvested apples and the careful culling of apples before pressing are good methods for reducing patulin levels in cider.     

A comparison of the flavonol content and composition in dessert,cooking and cider-making apples; distribution within the fruit and effect of juicing

The fruit of all apple varieties tested possessed five quercetin glycosides, namely hyperin, isoquercitrin, reynoutrin, avicularin and quercitrin, as the major flavonol components. Total flavonol levels were in the range 26.4 to 73.9μg/g fresh wt (expressed as aglycone) with hyperin the dominant form in all varieties except Egremont and Jonagored, where quercitrin predominated, and the cider apples, where avicularin predominated. The proportion of flavonol in the peel ranged from 63.0 to 97.1% for the dessert and cooking apples and was not dependent on fruit size. Juice produced from the three varieties of cider apple contained 9.9 to 12.7% of the flavonols with the remainder retained in the pomace.     

Use of hazard analysis critical control point and alternative treatments in the production of apple cider.

The purpose of this study was to evaluate the practices of Maryland cider producers and determine whether implementing hazard analysis critical control point (HACCP) would reduce the microbial contamination of cider. Cider producers (n = 11) were surveyed to determine existing manufacturing practices and sanitation. A training program was then conducted to inform operators of safety issues, including contamination with Escherichia coli O157:H7, and teach HACCP concepts and principles, sanitation procedures, and good manufacturing practice (GMP). Although all operators used a control strategy from one of the model HACCP plans provided, only one developed a written HACCP plan. None developed specific GMP, sanitation standard operating procedures, or sanitation monitoring records. Six operators changed or added production controls, including the exclusion of windfall apples, sanitizing apples chemically and by hot dip, and cider treatment with UV light or pasteurization. Facility inspections indicated improved sanitation and hazard control but identified ongoing problems. Microbiological evaluation of bottled cider before and after training, in-line apples, pomace, cider, and inoculated apples was conducted. E. coli O157:H7, Salmonella, or Staphylococcus aureus were not found in samples of in-line apple, pomace, and cider, or bottled cider. Generic E. coli was not isolated on in-coming apples but was found in 4 of 32 (13%) in-line samples and 3 of 17 (18%) bottled fresh cider samples, suggesting that E. coli was introduced during in-plant processing. To produce pathogen-free cider, operators must strictly conform to GMP and sanitation procedures in addition to HACCP controls. Controls aimed at preventing or eliminating pathogens on source apples are critical but alone may not be sufficient for product safety.     

Post-harvest application of diphenylamine and ethoxyquin for the control of superficial scald on Bramley's seedling apples

Recent changes in the antioxidant regulations in the UK and the need to evaluate the effectiveness of scald control chemicals in the presence of other post-harvest chemicals led to a comparative study of the effects of diphenylamine (DPA) and ethoxyquin on scald development in Bramley's Seedling apples. A range of concentrations (1000–4000 mg litre^?1 a.i.) of DPA completely controlled scald on Bramley apples kept in controlled atmosphere storage for 241 days; ethoxyquin at equivalent rates was less effective. Only partial control of scald was achieved with 500 mg litre^?1 a.i. DPA. None of the treatments injured the fruit. Control of scald by 2000 mg litre^?1 a.i. DPA or ethoxyquin was not impaired by adding thiophanate-methyl (l g litre^?1 a.i.) or calcium chloride (10 g litre^?1) although the measure of control was reduced when both fungicide and calcium chloride were added. Calcium chloride caused lenticel injury which was aggravated by adding ethoxyquin but reduced by incorporating DPA. The concentrations of ethoxyquin and DPA residues on the fruit immediately after treatment were within the limits required by UK legislation (see reference 1) of 3 mg kg^?1 and 10 mg kg^?1, respectively, even where 4000 mg litre^?1 had been applied. An initial residue concentration of 2.3 mg kg^?1 DPA was associated with complete control of scald. Residue levels, particularly of DPA, declined rapidly during the first month of storage.     

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.     

Effect of processing treatments on the characteristics of juices and still ciders from Ontario‐grown apples

Recent interest in the commercial production of cider in Ontario, Canada revealed a lack of information on cider prepared from apples grown in North America. A study was conducted using locally grown culinary and dessert varieties of apples, since there is a lack of true cider varieties grown in Ontario. Four processing methods (treatments) were evaluated with respect to their effect on juice and cider characteristics; the chemical and microbiological characteristics of the juices and still ciders are reported. Sulphite addition to the juice at the time of juice extraction had no effect on the characteristics evaluated. Storage of fruits at 13 °C until they showed signs of shrivelling or senescence decreased juice yield and affected titratable acidity and pH levels of juices and ciders. Freezing fresh apples and thawing prior to processing produced juices that did not undergo keeving and had higher mould and yeast populations; methanol was present in juices and ciders from thawed apples. The significant effects of storage and freezing on apple juice characteristics should be taken into account when considering a delay in the processing of apples for cider production. © 2003 Society of Chemical Industry     

Changes in the profile of volatile compounds and amino acids during cider fermentation using dessert variety of apples

In China, the production of apples is very large even surplus. Developing cider is becoming an important and promising segment of the fruit industry. Fuji apples, a most popular dessert variety in China, were employed to produce cider. Timely monitoring during the fermentation process was conducted by recording the changes in yeast biomass, total sugar content, reducing sugar content, total acidity, yeast assimilable nitrogen, total phenols content, amino acids and volatile compounds. The sugar and nitrogen compounds were consumed smoothly during fermentation. A variety of volatile compounds were detected in the fermentation liquor, mainly including eight higher alcohols, fourteen esters, six fatty acids, three aldehydes, one ketone, one volatile phenol and three terpenes. Their content was changing dynamically throughout the fermentation process. The sensory evaluation revealed a good acceptance of the cider. The results showed that Fuji apples are good raw material for cider and have the potential to be widely used in the China cider industry.     

Prevalence of Escherichia coli in apple cider manufactured in Connecticut.

Cider samples obtained from 11 cider mills operating in Connecticut during the 1997 to 1998 production season were tested for the presence of Escherichia coli. Cider production began in mid August and continued through March, with peak production in September and October. Of 314 cider samples tested, 11 (4%) were found to contain E. coli. Of the 11 mills, 6 (55%) tested positive for E. coli in the cider at least once during the production year. E. coli was first observed in cider samples produced in mid to late October and was not detected in samples made after January. A trend was observed for cider to decrease in acidity and increase in Brix (soluble sugars) throughout the production season. No correlation between pH and soluble sugars of cider and the presence of E. coli was detected. Eight mills used both dropped apples and tree-picked apples, whereas three mills used tree-picked apples only. The use of dropped apples in cider production began 5 weeks before the first detection of E. coli in cider. E. coli was isolated from cider samples produced using dropped apples and from samples produced using only tree-picked apples. No direct correlation between the use of dropped apples or tree-picked apples and the presence of E. coli in the cider was observed. An association between the time of apple harvest and the appearance of E. coli in cider was noted. For mills providing adequate records, all contaminated cider was produced from apples harvested between mid October and mid November.     

发酵对苹果渣多糖流变性的影响

以苹果渣多糖(apple pomace polysaccharide,APP)、酒渣多糖(cider apple pomace polysaccharide,CAPP)、醋渣多糖(cider vinegar apple pomace polysaccharide,CVAPP)为研究对象。通过APP、CAPP、CVAPP质量分数、温度、放置时间对表观黏度、剪切应力的影响对比,研究发酵对APP流变特性的影响。结果表明:APP、CAPP、CVAPP皆为假塑性流体,存在剪切变稀现象;CAPP、CVAPP表现出黏度明显降低、质量分数依赖性减弱、温度抗逆性增强以及存在一定的时间抗逆性;APP、CAPP、CVAPP放置3 d对流变特性影响较小;CAPP、CVAPP在一定程度上表现出优于APP的加工特性。     

Survival of Penicillium expansum and Patulin Production on Stored Apples after Wash Treatments

ABSTRACT: Penicillium expansum is a widespread fungus found on apples that causes fruit decay and may lead to production of a toxic secondary metabolite, patulin. This study was undertaken to evaluate the effectiveness of several chemical sanitizers against P. expansum NRRL 2304 and to establish sanitizing wash treatments that would inhibit P. expansum growth and subsequent patulin production on Empire apples destined for cider. Wash treatments included 200 ppm NaOCl, 1% StorOx®, 0.5% potassium sorbate, 300 ppm SO₂, and 0% to 5% acetic acid. Spores of P. expansum or inoculated apple slices were dipped in sanitizing wash solution for 5 min, and mold growth and patulin production was monitored on subsequent storage. It was found that 0.5% potassium sorbate and 300 ppm SO₂ did not affect mold survival or patulin production; 1% StorOx® was effective against mold spores in solution (4 log Most Probable Number destruction of spores), but there was no significant reduction in spore count when the same solution was used to sanitize mold‐inoculated apple discs. Washing with 200 ppm NaOCl delayed growth of P. expansum on inoculated apple discs but failed to completely inhibit patulin production. Acetic acid solution (2% to 5%) was the most efficient chemical against P. expansum. A wash treatment with ≥2% acetic acid for more than 1 min is recommended to completely inhibit growth of P. expansum and subsequent patulin production on apples destined for cider.     

Baby food production chain: pesticide residues in fresh apples and products.

During 3 years of a monitoring programme, 522 samples of fresh apples, six brands of fruit purées and various types of fruit baby food prepared from these materials were analysed. Each sample was examined for the presence of 86 GC amenable pesticide residues. The reporting limits of the procedure employed for sample analyses were in the range 0.003-0.01 mg kg(-1). Pesticide residues were detected in 59.5% of the samples of fresh apples. However, maximum residue levels (European Union MRLs) were exceeded only in 1.4% of samples. The levels of residues in 'positive' fruit purées were substantially lower, overall with residues detected in 33% of samples. Fruit baby food represented the commodity with the lowest incidence of residues being detected in only 16% of samples. The 0.01 mg kg(-1) MRL was exceeded in 9% of these products. Multiple residues were found in 25% of fresh apples and in 10% of fruit purées. None of fruit baby food samples contained more than a single residue. Organophosphorus insecticides and fungicides representing phtalimides, sulphamides and dicarboximides were the most frequently found residues. To obtain more knowledge on the fate of residues during fruit baby food production, processing experiments employing apples with incurred residues (fenitrothion, phosalone and tolylfluanid) were conducted. Washing of apples did not significantly reduce the content of pesticides. Steam boiling followed by removal of peels/stems was identified as the most efficient steps in terms of residues decrease (phosalone) or complete elimination (fenitrothion and tolylfluanid).     

中早熟苹果品种的贮藏品质和酚类物质差异分析

中早熟苹果品种可以丰富水果市场,是苹果产业重要的组成部分,研究其贮藏特性及品质差异意义重大。本实验以‘鲁丽’‘鲁艳’两个苹果新品种为研究对象,以其亲本‘嘎啦’为参照,探究3种苹果的贮藏品质和酚类物质差异。结果表明：相比于‘嘎啦’苹果,‘鲁丽’苹果可溶性固形物质量分数最高,果皮a*值最大,外观品质最佳、适于鲜食,而‘鲁艳’苹果总酸度高、固酸比低,贮藏期间乙烯释放量高,不耐贮藏。与‘嘎啦’和‘鲁艳’苹果相比,‘鲁丽’苹果有着最高的总酚、总黄酮含量和1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基清除率,抗氧化能力最强。3种苹果主要的酚类物质也因品种、成熟度和果实部位存在差异,‘嘎啦’和‘鲁丽’苹果果肉均以绿原酸含量最高,而‘鲁艳’苹果表儿茶素含量最高,果皮酚类物质含量高于果肉。相关性和主成分分析表明果实硬度与a*值有高度显著负相关性（P<0.001）,可溶性固形物质量分数与总酚、总黄酮、绿原酸含量和DPPH自由基清除率存在高度显著正相关（P<0.001）,主成分1主要由总酚、总黄酮、绿原酸、表儿茶素含量等指标决定,成熟...     

Effects of storage conditions and fruit processing on the degradation of parathion methyl on apples and lemons

Degradation of parathion methyl on lemon and apple on the trees, during storage of these fruits in refrigerated rooms, and during juice production was studied. The pesticide was applied to the trees according to the recommended application procedures. Apples and lemons received a single application of parathion methyl at 40 g active ingredient/100 litres. Residues were determined with a simple gas-chromatographic method; the recovery rate of parathion methyl from apples and lemons was 85-108% and the limit of determination was 0.004 mg kg^-1. The half-lives of parathion methyl on the trees were 7 days for apples and 5 days for lemons. The duration of storage of the fruits in a refrigerated room have been largely extended to 65 and 63 days, respectively. The high acidity of lemons was found not to affect the degradation rate of parathion methyl. When fruit juice was produced from both apples and lemons, parathion methyl residues were detected in apple but not in lemon juice.     

Efficacy of sanitation and cleaning methods in a small apple cider mill

The efficacy of cleaning and sanitation in a small apple cider processing plant was evaluated by surface swab methods as well as microbiological examination of incoming raw ingredients and of the final product. Surface swabs revealed that hard-to-clean areas such as apple mills or tubing for pomace and juice transfer may continue to harbor contaminants even after cleaning and sanitation. Use of poor quality ingredients and poor sanitation led to an increase of approximately 2 logs in aerobic plate counts of the final product. Reuse of uncleaned press cloths contributed to increased microbiological counts in the finished juice. Finally, using apples inoculated with Escherichia coli K-12 in the plant resulted in an established population within the plant that was not removed during normal cleaning and sanitation. The data presented in this study suggest that current sanitary practices within a typical small cider facility are insufficient to remove potential pathogens.     

Degradation of apple cell wall material by commercial enzyme preparations

The action of commercial enzyme preparations on the release of cell wall constituents from alcohol-insoluble substance prepared from apples without skins and cores as well as their influence on the water binding of remaining residues is described as a model for the enzymatic cell wall destruction during production of liquid fruit products. Besides 'normal' enzyme concentrations adapted from the usual industrial dosage, 'tenfold' enzyme concentrations were applied. Dependent on enzyme spectrum and activities, concentrations of dietary fibre, e.g., pectin, increased in the soluble fractions using conditions of enzymatic 'mash treatment'. A further release of these cell wall constituents occurred when cellulase containing enzyme preparations were used under conditions of 'pomace treatment', especially with the 'tenfold' enzyme dosage. The partial enzymatic degradation of the cell wall material is connected with a decrease in water binding of the remaining residues during both simulated mash treatment of pomace treatment. Alcohol-insoluble substance from apples is a suitable model for the determination of complex enzymatic actions of enzyme preparations containing pectolytic, hemicellulolytic, and/or cellulolytic activities under standardised conditions.     

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.     

Verifying apple cider plant sanitation and hazard analysis critical control point programs: choice of indicator bacteria and testing methods.

The objectives of this study were (i) to evaluate the survival of coliforms, Escherichia coli, and enterococci in refrigerated apple cider; (ii) to develop simple and inexpensive presumptive methods for detection of these bacteria; (iii) to perform a field survey to determine the prevalence of these bacteria on apples and in apple cider; and (iv) based on our results, to recommend the most useful of these three indicator groups for use in verifying apple cider processing plant sanitation and hazard analysis critical control point (HACCP) programs. Eight of 10 coliform strains (5 E. coli, 1 Enterobacter aerogenes, and 2 Klebsiella spp.) inoculated into preservative-free apple cider (pH 3.4, 13.3(o) Brix) survived well at 4 degrees C for 6 days (< or = 3.0 log10 CFU/ml decrease). Of 21 enterococci strains (Enterococcus faecalis, E. faecium, and E. durans), only 2 E. durans and 3 E. faecium strains survived well. Simple broth-based colorimetric methods were developed that detected the presence of approximately 10 cells of coliforms or enterococci. In three field studies, samples of unwashed apples (drops and picked), washed apples, and freshly pressed cider were presumptively analyzed for total coliforms, E. coli, and enterococci using qualitative and/or quantitative methods. Drop apples were more likely than picked apples to be contaminated with E. coli (26.7% vs. 0%) and enterococci (20% vs. 0%). Washing had little effect on coliform populations and in one field study was associated with increased numbers. Total coliform populations in cider ranged from < 1 CFU/ml to > 738 most probable number/ml, depending on the enumeration method used and the sample origin. E. coli was not recovered from washed apples or cider, but enterococci were present on 13% of washed apple samples. The qualitative coliform method successfully detected these bacteria on apples and in cider. Based on its exclusively fecal origin, good survival in apple cider, and association with drop apples, we conclude that E. coli is the most useful organism for verifying apple cider sanitation and HACCP programs.     

SURVEY OF APPLE GROWING, HARVESTING, AND CIDER MANUFACTURING PRACTICES IN WISCONSIN: IMPLICATIONS FOR SAFETY

To evaluate the safety of current apple growing, harvesting and cider manufacturing practices in Wisconsin, cider manufacturers were contacted in a three-phase survey. Results revealed that seasonal, small-scale production was characteristic of the industry. Most cider mills produced less than 5,000 gal/year; only 6% produced more than 20,000 gal/year. Most cider makers used only tree picked apples (86%), inspected apples before washing (94%), washed (93%) and brushed (87%) apples, but only 16% of mills sanitized washed apples. Most mills (92%) sanitized cider making equipment after each use; however, only a few sanitized between custom pressing apples from different customers. Respondents reported that they strived to improve cider safety by pasteurization (43% of all cider), UV light treatment (4%), use of preservatives (30%), and HACCP (17%). For 31% of all cider, however, processors relied solely on refrigeration and/or freezing. These results show that most cider mills practice many steps believed to enhance cider safety, but results also identify procedures that must be addressed to further improve cider safety.