INCIDENCE OF INDIGENOUS MICROBIAL FLORA FROM UTENSILS AND SURROUNDING AIR IN TRADITIONAL FRENCH CIDER MAKING

Lactic acid bacteria and yeasts were numerated, isolated and identified from two ciders obtained from similar raw materials used under different conditions. One cider was produced in a cellar of a traditional producer while the second one was produced under laboratory conditions. In both ciders alcoholic fermentation was achieved mainly by Saccharomyces cerevisiae. In the traditional cider, among the lactic acid bacteria (LAB) the species Leuconostoc oenos was predominant and malolactic conversion was observed. By contrast no development of LAB occurred in the second cider and therefore malolactic conversion was not achieved .     

Fatty acid composition of cider obtained either by traditional or controlled fermentation

A pilot-scale model for controlled fermentation in cider-making is described. This technology is compared with the conventional induction of alcoholic fermentation and spontaneous malolactic conversion on the basis of the cider’s fatty acid profile. Controlled cider fermentations were carried out by means of sequential inoculation of Saccharomyces cerevisiae and Leuconostoc oenos. It was observed that there are significant differences in fatty acid composition depending on the fermentation process employed. The contents in fatty acids of ciders elaborated by a conventional process were higher than those of ciders obtained by controlled fermentation. The use of principal component analysis (PCA), linear discriminant analysis (LDA), soft independent modeling of class analogy (SIMCA) and partial least squares (PLS) in conjunction with the fatty acid composition allowed the authors to typify fermented apple products on the basis of the fermented technology. The most relevant variables for classification purposes were lauric and palmitic acids.     

LACTIC ACID BACTERIA AND MALOLACTIC FERMENTATION IN THE MANUFACTURE OF SPANISH CIDER

Numeration, isolation and identification of the lactic acid bacteria found in Asturian cider during processing and storage has been carried out. The species Leuconostoc oenos was predominant during both alcoholic and malolactic fermentations. In most of the ciders studied the malolactic fermentation and the alcoholic fermentation started at the same time; production of D-lactate as well as a decrease of L-lactate were to be found once the malolactic fermentation was complete .     

CONTROLLED PRODUCTION OF CIDER BY INDUCTION OF ALCOHOLIC FERMENTATION AND MALOLACTIC CONVERSION

Characterization experiments involving lactic bacteria allowed a strain of Leuconostoc oenos to be selected in terms of growth capacity at variable pH, temperature, ethanol and sulphite concentrations, malic to lactic conversion yield, acetic acid uptake and dextran production capacity. Cider was produced under controlled conditions where the effect of Kloeckera apiculata yeasts on the development of Saccharomyces cerevisiae and production of major non-volatile compounds influencing end product quality was studied. The apiculate yeast was found to produce large amounts of acetic acid and use the other organic acids; also, it hindered fermentation to a certain extent. A study of the effect of the inoculation time with L oenos as an inducer of malolactic fermentation revealed sequential inoculation of the lactic bacterium once most major sugars in the must had been depleted to be the most favourable. Using yeast cell walls boosted fermentation development, as well as degradation of malic acid and synthesis of succinic and acetic acid.     

A SURVEY OF MICROBIOLOGICAL ASPECTS OF CIDER MAKING

Among the lactic microflora of ciders it was found that the species Leuconostoc oenos was predominant at the end of the alcoholic fermentation as well as at the end of the malo-lactic conversion. Among yeasts, the genera Saccharomyces was predominant at the end of fermentation. However, in the case of one juice characterised by a low initial level of bacteria, a high amount of phenolic compounds and a small quantity of total nitrogen, the whole lactic flora was no longer detected after a fortnight.     

Lactic Acid Bacteria in Spanish Red Rose and White Musts and Wines under Cellar Conditions

The dynamics of the lactic acid bacterial (LAB) population in different cellars, fermentation conditions and musts were analyzed. The number of LAB in fresh musts diminished quickly in the first few days, but an increase of these bacteria occurred during the later stages of the alcoholic fermentation. The species found in fresh musts were Lactobacillus plantarum, L. hilgardii, L. brevis, L. confusus, and Leuc. onostoc paramesenteroides. At the end of fermentation only L. hilgardii, Leuc. oenos and L. fructivorans were isolated. The API 50 CHL system was not useful to identify strains of Leuc. oenos species. All the isolated strains degraded malic acid in synthetic medium but only two strains belonging to Leuconostoc oenos species did it in wine.     

Effect of cider maturation on the chemical and sensory characteristics of fresh cider spirits

The influence of cider maturation on the chemical and sensory characteristics of fresh cider spirits was evaluated in the present study. To this end, a single-factor experiment with three maturation levels and five replicates (ciders) per level was developed. Level 1 corresponded to spirits obtained when alcoholic and malolactic fermentation of the ciders ceased, Level 2 corresponded to spirits obtained from ciders with a volatile acidity of 1.0 g/L acetic acid, while Level 3 corresponded to spirits made from ciders with a volatile acidity of 1.5 g/L acetic acid. Cider maturation significantly influenced the composition of the spirit as regards the ethyl esters of the major organic acids of cider (lactic, acetic and succinic). It also significantly influenced the content of aromas produced by bacterial activity (2-butanol, 2-propen-1-ol, 4-ethylguaiacol and eugenol), the concentration of which was found to increase with higher levels of maturation. The attributes “spicy” and “sweetness” were likewise influenced by the level of cider maturation. The distillates made from the most matured cider (volatile acidity 1.5 g acetic acid/L) scored better for “odour quality”.     

Incidence of Land and Physicochemical Composition of Apples on the Qualitative and Quantitative Development of Microbial Flora During Cider Fermentations

Lactic acid bacteria and yeasts were numerated, isolated and identified from ciders prepared with the same variety of apple from apple trees grown on three different lands: silt, siliceous clay and green clay. The land has an incidence on the time (earliness) of ripeness of the apples and on their sugar content and, therefore, on the development of the microbial flora in the ciders obtained from these fruits. The same genera of yeasts and lactic acid bacteria were isolated from the three ciders, except the yeast Candida famata exclusively found in the must obtained from apples grown on silt. At the quantitative level, the highest development of yeasts was observed in the must from the land green clay whereas lactic acid bacteria growth was enhanced in the must from the land siliceous clay.     

Glucons?ureverg?rung durch Milchs?urebakterien des Weines

Zusammenfassung Insgesamt 116 verschiedene, überwiegend aus Wein isolierte Stämme von Milchsäure-bakterien der GattungenLactobacillus, Leuconostoc, Pediococcus undStreptococcus wurden auf die Fähigkeit zur Verwertung von Gluconsäure untersucht. Bis auf einzelne Ausnahmen wurde Gluconsäure von denLactobacillus-Arten, die den UntergattungenStreptobacterium undBetabacterium angehörten, und der Mehrzahl derLeuconostoc-Stämme vergoren. VonPediococcus wurde Gluconsäure nicht abgebaut. Bei wachsenden Kulturen und ruhenden Zellen vonLactobacillus brevis, Lactobacillus casei undLeuconostoc oenos waren die Endprodukte des Gluconsäureabbaus Milchsäure, Essigsäure, Äthanol und CO₂. Milchsäure entsteht aus Gluconsäure in annähernd äquimolaren Mengen. In einem aus Wein und Hefeextrakt bestehenden Medium (pH 3,5) wurden 0,5 g Gluconsäure und 4,5 g Äpfelsäure je 1 vonLactobacillus brevis undLeuconostoc oenos vollständig abgebaut.

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Fermentation of gluconic acid by lactic acid bacteria isolated from wine

Summary The fermentation of gluconic acid was investigated in 116 different strains of lactic acid bacteria belonging to the generaLactobacillus, Leuconostoc, Pediococcus andStreptococcus. Most of the strains were isolated from wine. Gluconic acid was fermented by nearly all species of the genusLactobacillus (belonging to the subgeneraStreptobacterium andBetabacterium and by most strains ofLeuconostoc. The pediococci did not ferment gluconic acid. Growing cultures and resting cells ofLactobacillus brevis, Lactobacillus casei andLeuconostoc oenos formed lactic acid, acetic acid, ethanol and CO₂ from gluconic acid. Lactic acid was formed in about equimolar amounts from gluconic acid.Lactobacillus brevis andLeuconostoc oenos metabolised completely 0.5 g of gluconic acid and 4.5 g of malic acid per liter when cultured in a medium consisting of wine and a small amount of yeast extract (at pH 3.5).

     

Effect of co-inoculation of Saccharomyces cerevisiae and Lactobacillus fermentum on the quality of the distilled sugar cane beverage cachaça

Abstract: The effect of Lactobacillus fermentum in co‐inoculation with Saccharomyces cerevisiae UFLA CA11 on the quality of cachaça (sugar cane spirit) was evaluated. The co‐inoculation was first evaluated in flask fermentation, and subsequently, yeast and bacteria were co‐cultured at approximately 10⁵ CFU/mL and 10⁸ CFU/mL, respectively, in 4 consecutive batches. L. fermentum did not affect the growth or activity (sugar consumption and fermentation rate) of S. cerevisiae UFLA CA11 during fermentation. The physicochemical analysis revealed a higher concentration (Tukey test) of aldehydes (22.07 mg/100 mL anhydrous alcohol) in cachaça produced by co‐inoculation. Analysis of volatile compounds using GC‐FID demonstrated that cachaça produced by co‐inoculation had higher concentrations of acetaldehyde (25.15 mg/L), ethyl acetate (30.17 mg/L), and 2,3‐butanedione (170.39 μ/L), while cachaça produced by UFLA CA11 contained higher concentrations of ethyl lactate (1205.98 μ/L), propionic acid (127.97 μ/L), butyric acid (2335.57 μ/L), and 1‐pentanol (469.23 μ/L). The lowest concentration of acetic acid measured by HPLC was found in cachaça obtained with UFLA CA11. The sensory analysis, performed using the Mann–Whitney test, revealed that cachaça produced by co‐inoculation differed from that produced by UFLA CA11 in taste and aroma. Practical Application: This study reports on the use of a mixed culture of Saccharomyces cerevisae and Lactobacillus fermentum to produce cachaça and shows the influence of co‐inoculation of yeast and bacteria on the quality of this beverage.     

Production of L‐Lactic Acid from Spent Grain,a By‐Product of Beer Production

L‐lactic acid production from spent grain with immobilized lactic acid bacteria was investigated. Spent grains were liquefied by a steam explosion treatment to obtain liquefied sugar. When 1 kg of wet spent grain was treated under the 30 kg/cm²pressure for 1 min using a 5‐L steam explosion reactor, 60 g of total sugar was obtained from the liquefied spent grain. Furthermore, 1.3% (w/v) of glucose, 0.4% (w/v) of xylose, and 0.1% (w/v) of arabinose were produced when the liquefied spent grain was treated with glucoamylase, cellulase, and hemicellulase enzymes. When batch L‐lactic acid production was carried out by Lactobacillus rhamnosus NBRC14710, 19.0 g/L L‐lactic acid was produced from the Tween 80 liquefied spent grain after 5 days. Furthermore, during repeated batch production with immobilized Lactobacillus rhamnosus NBRC14710 from Tween 80 liquefied spent grain at 37°C, the productivity of L‐lactic acid was maintained at a 10 time higher level over a period of 40 days.     

Proteolysis in dry‐aged loins manufactured with sonicated pork and inoculated with Lactobacillus casei ŁOCK 0900 probiotic strain

Selected parameters related to proteolysis were evaluated in dry‐aged loins manufactured with sonicated pork and inoculated with Lactobacillus casei ?OCK 0900 probiotic strain. Dehydration, pH, water activity and total nitrogen content were not affected by ultrasound treatment. Neither sonication nor inoculation has an influence on L* and a* colour parameters. Sonication significantly influenced the pattern of proteolysis providing higher nonprotein nitrogen content (NPN) and proteolysis index (PI). The highest intensity of proteolysis, as assessed by NPN and PI, occurred in an inoculated sample. Neither sonication nor inoculation with L. casei had a significant effect on total viable counts. Loins inoculated with L. casei had the highest lactic acid bacteria count, followed by the sonicated and nonsonicated control. This research shows that sonication followed by inoculation with L. casei ?OCK 0900 could be used as an effective measure to speed up the proteolytic changes in dry‐aged meat cuts.     

YEAST STRAIN AND KINETIC ASPECTS OF THE FORMATION OF FLAVOUR COMPONENTS IN CIDER

An apple juice was fermented at 8°C using twelve strains of Saccharomyces uvarum. Glucose, fructose, malic and L-lactic acids, isobutanol, 2,3 butanediol, isoamyl alcohol, ethyl acetate and titratable acidity were determined and monitored in the course of fermentation. It was observed that yeast strains differed from one another mainly in fermentation rates. When components were determined in ciders of the same remaining fructose concentration, rather than after the same fermentation time, the only significant effect of the yeast strain was on the amounts of glucose and ethanol in sweeter cider (fructose 34 g/litre), or on the amounts of glucose, acetic acid, isobutanol and amyl alcohols in dryer ciders (fructose 17 g/litre). A sensory analysis showed that standard deviations of concentrations of remaining or formed components in ciders fermented by different yeast strains, was sufficient to be detected by the taste panel. Added glucose in this range of concentration (1.5 g/litre) in cider reduced the perception of sourness while the addition of acetic acid (0.3 g/litre) reduced the perception of the scented flavour. Added Isobutnol (6 mg/litre) reduced the perception of sweetness. No significant effect of added isoamyl alcohol (30 mg/litre) could be detected. Chemical determinations were correlated by means of regression equations derived from earlier work with some organoleptic characteristics. No anticipated effect of the yeast strain could be detected on any studied flavour characteristic. It is concluded that in ciders of the same attenuation, the effect if it does exist, of the S.uvarum strain isolated from ciders, must be low.     

Addition of fumaric acid and sodium benzoate as an alternative method to achieve a 5-log reduction of Escherichia coli O157:H7 populations in apple cider

A study was conducted to develop a preservative treatment capable of the Food and Drug Administration-mandated 5-log reduction of Escherichia coli O157:H7 populations in apple cider. Unpreserved apple cider was treated with generally recognized as safe acidulants and preservatives before inoculation with E. coli O157:H7 in test tubes and subjected to mild heat treatments (25, 35, and 45 degrees C) followed by refrigerated storage (4 degrees C). Fumaric acid had significant (P < 0.05) bactericidal effect when added to cider at 0.10% (wt/vol) and adjusted to pH 3.3, but citric and malic acid had no effect. Strong linear correlation (R2 = 0.96) between increasing undissociated fumaric acid concentrations and increasing log reductions of E. coli O157:H7 in apple cider indicated the undissociated acid to be the bactericidal form. The treatment that achieved the 5-log reduction in three commercial ciders was the addition of fumaric acid (0.15%, wt/vol) and sodium benzoate (0.05%, wt/vol) followed by holding at 25 degrees C for 6 h before 24 h of refrigeration at 4 degrees C. Subsequent experiments revealed that the same preservatives added to cider in flasks resulted in a more than 5-log reduction in less than 5 and 2 h when held at 25 and 35 degrees C, respectively. The treatment also significantly (P < 0.05) reduced total aerobic counts in commercial ciders to populations less than those of pasteurized and raw ciders from the same source (after 5 and 21 days of refrigerated storage at 4 degrees C, respectively). Sensory evaluation of the same ciders revealed that consumers found the preservative-treated cider to be acceptable.     

Effect of Vitamin Supplements on Growth of Leuconostoc oenos 44.40

Media sterilization procedures were studied during the production of a starter culture, Leuconostoc oenos 40·40, for use in malolactic fermentation of wine. Heat and filter sterilization of yeast extract was compared with respect to the growth of L. oenos. Addition of a mixture of vitamins after heat sterilization of basal medium with yeast extract stimulated the growth of this organism. When used alone, each vitamin except nicotinic acid had a stimulatory effect on growth. During pilot fermentation the production of bacterial cells per hour was doubled when vitamins were supplemented after sterilization of medium. Vitamin supplementation also increased the viability of lyophilized cells.     

Estimation of the monomeric phenolics of ciders

A method is described for the separation and quantitative determination of the monomeric phenolics of ciders. These are fractionally eluted from a silica-gel column with 2-methylpropan-2-ol/chloroform mixtures of increasing 2-methylpropan-2-ol content. The u.v. spectrum of each fraction is obtained in the range 250-400 nm. Fractions containing hydroxycinnamic acid esters of quinic acid are first irradiated with u.v. light to equilibrate cis and trans forms. The concentration of each of the phenolics is calculated from extinctions at appropriate wavelengths. Ciders from some cider-apple cultivars contained in order of decreasing concentration 5-chlorogenic acid, 4-p-coumarylquinic acid, catechins, phloridzin and phloretin xyloglucoside. In one cultivar catechins were undetectable while in others they exceeded the p-coumarylquinic acid. The contribution of the phenolics to the tannin content is discussed.     

Mixed Culture Fermentation of Cucumber Juice with Lactobacillus plantarum and Yeasts

Saccharomyces cerevisiae and Saccharomyces rosei were tested for use in mixed culture fermentation of cucumber juice with Lactobacillus plantarum. Extent of sugar utilization and the ratio of products formed (lactic acid:ethanol) were influenced by time of inoculation and cell numbers of each microorganism. Sugar fermentation was complete within 6 days at 28°C when similar numbers of bacteria and yeasts were added simultaneously, or when yeasts were added before the bacteria. Sugar remained when only L. plantarum was added, or when yeasts were added in low numbers. Glycerol was produced when yeasts were present, the concentration being directly related to NaCl concentration. Results suggest advantageous uses of yeasts to complete fermentation and to modify acidity.     

Improvement of volatile composition of wines by controlled addition of malolactic bacteria

The effect of malolactic fermentation (MLF) on the volatile composition of red wines was studied by inoculation with selected lactic acid bacteria. Four wines were inoculated with different Oenococcus oeni (syn. Leuconostoc oenos) strains, the major malolactic species found in wines, and one was inoculated with a Lactobacillus sp. strain. A non inoculated wine was also analyzed to act as a control. Malolactic fermentation and evolution of non volatile compounds were followed by HPLC and after the depletion of the malic acid present in wine the volatile compounds were extracted and analyzed by gas chromatography with flame ionization and mass spectrometry. Wines which had undergone the MLF showed a significant increment in total higher alcohols, esters and acids that are important in the sensory properties and quality of wine.     

Production of Citric Acid from Beet Molasses by Immobilized Cells of Aspergillus niger

Citric acid was produced from beet molasses by immobilized cells in shake flasks and glass bioreactor. Maximum concentration of citric acid (35 g/L) was observed from immobilized A. niger cells in shake flasks after 28 days fermentation. In repeated batch fermentations, the A. niger cells entrapped in Ca-alginate gel beads retained ability to produce citric acid for up to 84 days.