Cider Quality Research Articles

Genetic and physiological studies onOenococcus oeniPsuI in response to ethanol stress

Malolactate fermentation (MLF), which is known to decreases total acidity and improves the stability and quality of cider is conducted by Oenococcus oeni; the principal microorganism responsible for MLF under stress conditions. Understanding O. oeni physiology in stress conditions can be used to generate tools based on molecular and physiological approaches allowing more precise characterization of strains. Regarding intracellular protein, the results showed an increase in the levels of amino acids under ethanol stress. To study the expressed genes under ethanol stress, one gene were sequenced. An outer-membrane lipoprotein carrier protein precursor, Lo1A was expressed under ethanol stress conditions. Scanning electron microscopy was used to study the effect of ethanol stress on cell morphology. SEM revealed aggregation of bacterial cells as the level of ethanol increases in culture medium in comparison to controls.

THERMAL AND NONTHERMAL PROCESSING OF APPLE CIDER: STORAGE QUALITY UNDER EQUIVALENT PROCESS CONDITIONS

ABSTRACT Three processing techniques: heat, pulsed electric field (PEF) and ultraviolet (UV) light were optimized to achieve a similar 6 log reduction of inoculated Escherichia coli K12 in apple cider. Microbial populations (total aerobic and yeast and mold), sensory, color and physical properties (pH and°Brix) of processed apple cider were investigated during 4‐week storage at 4C. PEF and thermally processed cider maintained good microbial quality during 4 weeks of storage while UV‐treated cider showed a significant (P < 0.05) growth in yeast and mold after 2 weeks of storage. As a result,°Brix value decreased significantly (P < 0.05) for UV cider after 4 weeks of storage. Apple cider pH was neither affected by any treatment nor by storage. Thermal and UV‐pasteurized ciders faded significantly (P < 0.05) during storage (International Commission on Illumination L*[lightness] and b*[yellow] values increased) compared to PEF cider. Triangle sensory analysis indicated a significant difference (P < 0.05) in aroma between treatments. PEF‐treated cider was preferred over thermal and UV cider by sensory panelists at the end of the storage period. The results suggested that PEF‐treated apple cider had a longer shelf life than UV‐treated cider and a better aroma and color than thermally processed sample.PRACTICAL APPLICATIONSNonthermal processes like pulsed electric field (PEF) and ultraviolet (UV) light are developed as alternative pasteurization technologies to heat for their efficacy to extend shelf life and enhance the safety of fresh juice while preserving organoleptic and nutritional qualities. For fair comparison of the effects on quality of juice, both thermal and nonthermal processes must achieve equivalent reduction in microorganism levels. In the present study, the effect of PEF, UV and thermal techniques on apple cider quality are compared at conditions optimized to achieve equivalent 6 log reductions in Escherichia coli. Our results showed that PEF extended the shelf‐life of apple cider by inactivating spoilage microorganisms compared to UV processing, and better preserved the freshness (aroma and color) over traditional thermal processing. Based on these results, PEF process is the best choice among the three technologies studied.

Analysis of key aroma components in cider from Shaanxi (China) Fuji apple

SummaryAroma components play an important role in the quality of cider. To understand the contribution of every component to cider aroma quality, major aroma components present in ten ciders processed with different technological methods with different yeasts and apple orchards were determined by Headspace‐solid phase microextraction–gas chromatography–mass spectrometry and internal standard method. Experimental results by principal component analysis indicated that ethyl acetate, acetic acid isobutylester, isopentylacohol acetate, ethyl caprylate, ethyl 4‐hydroxybutanoate, isopentylalcohol, 3,4,5‐trimethyl‐4‐heptanol, nonyl alcohol, 3‐methylthio‐1‐propanol serve as the key aroma components in cider from Shaanxi (China) fuji apple. A model was established and verified for evaluating aroma quality based on factor analysis by comparing with the sensory evaluation method.

Calibration models for routine analysis of cider by mid-infrared spectroscopy

Partial least square regression was used to develop different calibration data sets for multi-parameter routine analysis of ciders. Parameters included were those related with the monitoring of fermentation process and cider quality: specific gravity, total and volatile acidities, alcoholic proof, pH and fructose. Calibration performances were evaluated by means of the prediction residual sum of squares (PRESS), the root mean squared prediction error of cross-validation (RMSECV) and the residual predictive deviation (RPD) values (ratio of the standard deviation of the population to the standard error of cross-validation). Validation of the models was assessed in terms of accuracy and precision. Mean recoveries of the predicted results compared to the reference values were close to 100%, with repeatability and reproducibility similar to those of the reference methods.

THE EFFECTS OF THERMAL AND NONTHERMAL PROCESSING METHODS ON APPLE CIDER QUALITY AND CONSUMER ACCEPTABILITY

ABSTRACT Due to increased concern about the safety of fruit, vegetable and juice products, the FDA has mandated that these must undergo a 5‐log reduction in pathogens. The development of various processing methods for juice products has caused the need to determine the effects of these methods on said products. The effect of thermal pasteurization, UV irradiation and ozone treatment on apple cider quality and consumer acceptability was studied over 21 days. Thermally pasteurized samples were different in color and less preferred in all areas of consumer acceptability. UV‐irradiated samples were lower in soluble solids for the first 7 days and showed no significant difference in consumer acceptability. Ozone‐treated cider had greater sedimentation, lower sucrose content and a decrease in soluble solids by day 21. UV irradiation allows for a more cost‐effective method to produce safe apple cider with minimal quality and consumer acceptability differences.

Influence of Cider-Making Technology on Cider Taste

Some major cider taste components (organic acids, sugars, alcohols and pectin substances) together with the microorganisms responsible for fermentations were determined in 12 ciders obtained by different technological methods in order to evaluate the quality of cider obtained. An analysis of variance revealed that the speed of pressing and the clarification system were the main factors influencing the efficiency of alcoholic fermentation, the speed of malolactic conversion and the microbiological stabilization of the cider.

Long Ashton Research Station

Long Ashton's origins were related to early interests in food science, for in the 19th Century when Somerset was a wheat‐producing county, each farm made its own cider as an incentive for the hand reapers. But cider quality varied greatly and, in 1893, the Bath and West Society initiated experiments into cider making. On the basis of ten years' results, reported to the Board of Agriculture, the National Fruit and Cider Institute was established on a 14‐acre site at Long Ashton in 1903. Under the Agricultural Development Act of 1909, Long Ashton received further support to widen its activities as one of the new National Agricultural Research Institutes. Since 1912, the Station has been a Department of the University of Bristol, and is also one of the thirty institutes under the aegis of the Agricultural Research Council.