Use of grape racemes from Grillo cultivar to increase the acidity level of sparkling base wines produced with different Saccharomyces cerevisiae strains

The most important oenological characteristics of high-quality sparkling wines are aromatic aspect, taste persistence, perlage, high levels of acidity and low pH. Due to hot climate and reduced rainfall that characterize Sicily region, white grape varieties such as Grillo cultivar cultivated in this area are characterized by very low concentrations of malic and tartaric acids. Grillo cultivar is characterized by an intense production of raceme grapes with low pH and high content of tartaric and malic acids. These fruits possess the chemical properties useful to increase the amounts of acids in the final wines. With this in mind, the present research was carried out to test the ability of four Saccharomyces cerevisiae strains (CS182, GR1, MSE13 and MSE41) to ferment a raceme must with a pH of 2.9 at two concentrations (14° and 16° Babo degree) of total sugars. The inoculation of the strains was performed after a preadaptation at pH 2.5. The chemical parameters and kinetics of the fermentations were monitored. The experimental sparkling base wines were characterized by a very high total acidity with 16–17 g/L of tartaric acid and 9–10 g/L of malic acids. On the other hand, ethanol was detected at low values in the range 9–10% (v/v). The base wine obtained with GR1differed in their high acidity values, whereas trials inoculated with CS182 showed more intense odors and exotic fruit. Experimental wines produced in this study represent an innovative strategy for “blending wines” to produce sparkling wines in dry Mediterranean climate.     

Inactivation of Escherichia coli in orange juice using ozone

This research investigated the efficacy of gaseous ozone for the inactivation of Escherichia coli ATCC 25922 and NCTC 12900 strains in orange juice. Orange juice inoculated with E. coli (10⁶ CFU mL^− 1) as a challenge microorganism was treated with ozone at 75–78 µg mL^− 1 for different time periods (0–18 min). The efficacy of ozone for inactivation of both strains of E. coli was evaluated as a function of different juice types: model orange juice, fresh unfiltered juice, juice without pulp, and juice filtered through 500 µm or 1 mm sieves. Fast inactivation rates for total reduction of E. coli were achieved in model orange juice (60 s) and in juice with low pulp content (6 min). However, in unfiltered juice inactivation was achieved after 15–18 min. This indicated that juice organic matter interferes with antibacterial activity of gaseous ozone. The effect of prior acid (pH 5.0) exposure of E. coli strains on the inactivation efficacy of ozone treatment was also investigated. There was a strain effect observed, where prior acid exposure resulted in higher inactivation times in some cases by comparison with the control cells. However, the overarching influence on inactivation efficacy of ozone was related to the pulp content. Generally, the applied gaseous ozone treatment of orange juice resulted in a population reduction of 5 log cycles.

Industrial relevance

To facilitate the preservation of unstable nutrients many juice processors have investigated alternatives to thermal pasteurisation, including un-pasteurised short shelf life juices with high retail value. This trend has continued within the European Union. However within the US recent regulations by the FDA have required processors to achieve a 5-log reduction in the numbers of the most resistant pathogens in their finished products. Pathogenic E. coli may survive in acid environments such as fruit juices for long periods. This study demonstrates that the use of ozone as a non-thermal technology is effective for inactivation of E. coli and acid exposed E. coli in orange juice. Information on the design of the ozone treatment for inactivation of E. coli which results into safe juice products is also among the main outputs of this work. Ozone auto-decomposition makes this technology safe for fruit juice processing.     

Identification of Natural Antimicrobial Substances in Red Muscadine Juice against Cronobacter sakazakii

ABSTRACT: Red muscadine (Vitis rotundifolia Michx.) juices with natural organic, phenolic acids and polyphenol compounds were tested against Cronobacter sakazakii. The concentration of total phenolic compounds of commercial baby juices ranged from 176.7 to 347.7 mg/mL. Commercial baby juices showed poor antimicrobial activity, reducing less than 1-log of C. sakazakii in juice samples for 2 h at 37 °C. Red muscadine juices, regardless of processing methods (filtration, pasteurization, and sterilization), achieved a 6-log reduction of C. sakazakii in the same time period (2 h). The mixture of synthetic organic acids (malic and tartaric acids) and polyphenolic acid (tannic acid) showed strong antimicrobial activity against C. sakazakii. Among synthetic organic acids, tannic acid was undetected in commercial baby juices. Tannic acid showed the highest antimicrobial activity (1.4- to 3.8-log reduction) against C. sakazakii, while malic and tartaric acids showed less than 0.5-log reduction. These results suggest that red muscadine juice could be utilized as a natural antimicrobial in baby food formulations to inhibit C. sakazakii.     

Initial Saccharomyces cerevisiae concentration in single or composite cultures dictates bioprocess kinetics

The growth dynamics of three non-Saccharomyces strains in combination with Saccharomyces cerevisiae during fermentation of a sterile grape juice have been studied. The influence of the initial concentrations of S. cerevisiae on the whole yeast community was the main purpose of this research. The progression of S. cerevisiae within the first 5 days of fermentation was monitored by enumeration on selective and non-selective media. The population of each species was evaluated by morphological criteria. After 24 h, Hanseniaspora uvarum represented more than 50% of the whole yeast community, including ferments with the highest initial concentration of S. cerevisiae. As the population of S. cerevisiae increased, H. uvarum decreased. Metchnikowia pulcherrima was more inhibited by S. cerevisiae than H. uvarum, whereas the growth of Candida stellata was less inhibited. After thirty days, irrespective of the initial concentration of S. cerevisiae, only S. cerevisiae was detected in all ferments. Conversion of sugars to ethanol correlated with the initial population of S. cerevisiae. Glucose was almost completely exhausted in all cases, independent of the initial S. cerevisiae concentration used. Grape juices inoculated with composite inocula of non-S. cerevisiae and S. cerevisiae, with its initial concentration lower than 5 cfu/ml did not produce wines according to wine regulations. The concentration of ethanol in the wines did not reach the minimum amount of 9 vol%. Samples of wines fermented with a composite inoculum the concentration of S. cerevisiae represented 50 cfu/ml of grape juice, were judged to have the best sensorial properties.     

Enhanced deacidification activity in Schizosaccharomyces pombe by genome shuffling

A problem frequently occurring in making some kinds of wines, particularly Vitis quinquangularis Rehd wine, is the presence of malic acid at high concentrations, which is detrimental to the quality of wines. Thus, there is a need of the ways for effectively reducing the malic acid levels in wine. This study aimed to generate shuffled fusants of Schizosaccharomyces pombe with enhanced deacidification activity for reducing the excessive malic acid content in wine. Sz. pombe CGMCC 2.1628 was used as the original strain. The starting mutant population was generated by UV treatment. The mutants with higher deacidification activity were selected and subjected to recursive protoplast fusion. The resulting fusants were screened by using the indicator of malic acid concentration of fermentation supernatants on 96‐well microtitre plates, measured with bromocresol green. After three rounds of genome shuffling, the best‐performing fusant, named GS3‐1, was obtained. Its deacidification activity (consumed 4.78 g/l malic acid within 10 days) was increased by 225.2% as compared to that of original strain. In the Vitis quinquangularis Rehd wine fermentation test, GS3‐1 consumed 4.0 g/l malic acid during the whole cycle of fermentation, providing up to 185.7% improvement in malic acid consumption compared with that of the original strain. This study shows that GS3‐1 has great potential for improving the quality of Vitis quinquangularis Rehd wine. Copyright © 2014 John Wiley & Sons, Ltd.     

Comparison of the Baird–Parker agar and 3MPetrifilmrapid S. aureus count plate methods for detection and enumeration of Staphylococcus aureus

This study compared Baird–Parker (B–P) agar plating with the 3M^TMPetrifilm^TMrapid S. aureus count plate method (PFRSA) for detection and enumeration ofStaphylococcus aureus . Sampling of deli-sliced meats (n=11) and cheeses (n=39), meat sandwiches (n=7) and raw bovine milk (n=14) revealed B–P to be insufficiently selective. Even with narrow identification criteria for presumptive S. aureus, 73% of 84 isolates from B–P were not S. aureus. None of the meat, cheese or sandwich samples tested positive using the PFRSA method. All 14 raw bovine milk samples tested positive for S. aureus using the PFRSA method and confirmed S. aureus isolates were recovered from 12 samples on B–P plates. Results of two storage studies using inoculated Swiss and mozzarella cheeses showed that the two enumeration methods were essentially equivalent and that increases in S. aureus numbers of more than 2 log cfu are unlikely on Swiss and mozzarella cheeses stored at ≤25°C for ≤20 h. Despite a high-temperature incubation step that prevented isolate confirmation, the PFRSA method was found to be a suitable alternative to B–P for detecting and enumerating S. aureus. Because of the relative speed of the PFRSA method, analysts may consider using it as an initial screen with positive samples re-tested using the B–P method, with subsequent testing, e.g. coagulase, of isolates.     

Identification and characterization of Dekkera bruxellensis, Candida pararugosa, and Pichia guilliermondii isolated from commercial red wines

Yeast isolates from commercial red wines were characterized with regards to tolerances to molecular SO₂, ethanol, and temperature as well as synthesis of 4-ethyl-phenol/4-ethyl-guaiacol in grape juice or wine. Based on rDNA sequencing, nine of the 11 isolates belonged to Dekkera bruxellensis (B1a, B1b, B2a, E1, F1a, F3, I1a, N2, and P2) while the other two were Candida pararugosa (Q2) and Pichia guilliermondii (Q3). Strains B1b, Q2, and Q3 were much more resistant to molecular SO₂ in comparison to the other strains of Dekkera. These strains were inoculated (10³–10⁴ cfu/ml) along with lower populations of Saccharomyces (<500 cfu/ml) into red grape juice and red wine incubated at two temperatures, 15 °C and 21 °C. Although Saccharomyces quickly dominated fermentations in grape juice, B1b and Q2 grew and eventually reached populations >10⁵ cfu/ml. In wine, Q3 never entered logarithmic growth and quickly died in contrast to Q2 which survived >40 days after inoculation. B1b grew well in wine incubated at 21 °C while slower growth was observed at 15 °C. Neither Q2 nor Q3 produced 4-ethyl-phenol or 4-ethyl-guaiacol, unlike B1b. However, lower concentrations of volatile phenols were present in wine incubated at 15 °C compared to 21 °C.     

Characterisation of malolactic conversion by Oenococcus oeni to reduce the acidity of apple juice

The high concentration of malic acid is responsible for the acidity and sourness in apple juice. Bio‐conversion of malic acid to lactic acid through malolactic conversion (MC) in apple juice using Oenococcus oeni was investigated. When apple juice was inoculated with O. oeni (1 × 10⁶ CFU mL^?1), over 90% of malic acid was converted into lactic acid within 96 h at room temperature. When pH of apple juice was adjusted to 4.1 prior to inoculation, MC was completed within 60 h. MC was enhanced at a higher temperature (30°C) when compared with room temperature. The rate of MC was directly proportional to the number of bacteria added and MC was completed within 24 h at 1 × 10⁹ CFU mL^?1 initial cell density. MC occurred equally under aerobic and anaerobic conditions. The sensory analysis of partial MC‐applied juice when compared against control revealed potential for use of MC for manufacture of low‐acid apple juice.     

Evaluation of malolactic-deficient strains of Lactobacillus plantarum for use in cucumber fermentations

In the fermentation of cucumbers, naturally occurring strains of Lactobacillus plantarum decarboxylate malic acid (MDC⁺) to form lactic acid and CO₂. Since CO₂ buildup in the brine contributes to bloater damage of the cucumbers, it is desirable to have strains of L. plantarum that do not decarboxylate malic acid (MDC^-1). Two MDC^- mutants, obtained by N-methyl-N′-nitro-N-nitrosoguanidine mutagenesis of different MDC⁺ strains, and their parent strains of L. plantarum wre evaluated in laboratory fermentations of filter-sterilized cucumber juice and of whole cucumbers as to growth rate, end-products, residual malic acid, and competitiveness with the natural flora. Effects of temperature (15 to 40°C) and NaCl concentration (0-6%) on growth in cucumber juice were determined. One MDC^-1 strain, designated MOP3-M6, was selected for further development because of its relative dominance in cucumber ferementations, high residual malic acid concentration after fermentation and greater salt tolerance as compared to its closest rival mutant culture. Growth lag and generation times averaged 1·6 and 1·2 times greater, respectively, for the MOP3-M6 mutant than its parent. However, this mutant may still have application as a starter culture for cucumber fermentation, particularly under relatively aseptic conditions.     

Inactivation of Listeria monocytogenes during drying and storage of peach slices treated with acidic or sodium metabisulfite solutions

This study evaluated whether treating inoculated peach slices with metabisulfite or acidic solutions enhanced inactivation of Listeria monocytogenes during dehydration and storage. Inoculated (five strain mixture of L. monocytogenes, 7.9 log cfu/g) peach slices were treated, dried for 6 h at 60°C and stored aerobically at 25°C for 14 d. Predrying treatments of inoculated peach slices included: (1) no treatment (control); or 10 min immersion in: (2) sterile water, (3) 4.18% sodium metabisulfite, (4) 3.40% ascorbic acid, or (5) 0.21% citric acid solutions. Samples were plated on tryptic soy agar with 0.1% pyruvate (TSAP) and PALCAM agar for enumeration of surviving bacteria. Immersion in sterile water reduced bacterial populations on peach slices by 0.7 log cfu/g (TSAP and PALCAM). Immersion in the sodium metabisulfite solution reduced populations by 1.5–2.0 log cfu/g, while acidic pretreatments reduced populations by 0.5–0.8 log cfu/g. After 6 h of dehydration, populations on control or water immersed slices were reduced by 3.2–3.4 log cfu/g, whereas populations on slices treated with sodium metabisulfite or acidic solutions were reduced by 4.3–5.1 log cfu/g (TSAP) and 5.3–6.2 log cfu/g (PALCAM), respectively. Bacteria were detectable by direct plating at 14 d of storage, except on acid treated slices. Immersion in acidic or metabisulfite solutions, before dehydration, should enhance inactivation of L. monocytogenes contamination on peach slices during dehydration and storage.     

Progress in wine authentication: GC–C/P–IRMS measurements of glycerol and GC analysis of 2,3-butanediol stereoisomers

The determination of glycerol and 2,3-butanediol by photometric or enzymatic methods is well established. This paper reports on the direct assessment of glycerol and stereoselective analysis of 2,3-butanediol isomers in wine using capillary GC without any derivatisation. A “model wine” and commercially available wines, as well as wines of definite origin were investigated. The contents of glycerol and 2,3-butanediol and the ratio of (R,R)- and meso-2,3-butanediol were determined. Capillary GC has proved to be a reliable alternative in glycerol assessment from wine, thus a GC-IRMS method for authenticity assessment of glycerol was developed.δ¹³C_V‐PDB and δ¹⁸O_V‐SMOW multi-element IRMS-analysis of glycerol, an important by-product of wine fermentation, is reported. For that reason glycerol, extracted from a self-prepared “model wine”, from wines of definite origin, as well as commercially available wines, was investigated. Furthermore, the ¹⁸O/¹⁶O and ¹³C/¹²C isotope ratios of commercial glycerols from different origins were determined. In addition fermentation experiments with beet and cane sugar, and with grape juices were carried out. In order to check the influence of water on the oxygen isotope ratios, water from different places in Germany was used in the fermentation experiments with cane and beet sugar.     

Destruction of acid- and non-adapted Listeria monocytogenes during drying and storage of beef jerky

Presence of Listeria monocytogenes in ready-to-eat meat products is not desired and strictly regulated in the US. Inactivation of acid- and non-adapted L. monocytogenes inoculated on beef slices was studied during drying and storage of jerky formulated with modified marinades. The inoculated (five-strain composite, c. 6·2 log cfu cm⁻²) slices were subjected to marinades (4°C, 24 h) prior to drying (60°C for 10 h) and aerobic storage (25°C for 60 days). The predrying marinade treatments tested were, first, no treatment, control (C); second, traditional marinade (TM); third, double amount of TM modified with 1·2% sodium lactate, 9% acetic acid, and 68% soy sauce containing 5% ethanol (MM); fourth, dipping into 5% acetic acid for 10 min and then applying the TM (AATM); and fifth dipping into 1% Tween 20 for 15 min and then into 5% acetic acid for 10 min followed by the TM (TWTM). Bacterial survivors on beef slices were determined during drying and storage using tryptic soy agar with 0·1% pyruvate (TSAP), and PALCAM agar. Results indicated that drying reduced bacterial populations in the order of pre-drying treatments TWTM (5·9–6·3 log cfucm⁻² in 10 h)≥AATM≥MM>TM≥C (3·8−4·6 log cfucm⁻² in 10 h). No significant (P≥0·05) difference was found in inactivation of acid-adapted and non-adapted inocula within individual treatments. Bacterial populations dropped below the detection limit (−0·4 log cfucm⁻²) as early as 4 h during drying or remained detectable even after 60 days of storage depending on acid-adaptation, predrying treatment, and agar media. These results indicated that acid-adaptation may not increase resistance to microbial hurdles involved in jerky processing and that use of modified marinades may improve the effectiveness of drying in inactivating L. monocytogenes.     

The aromatic volatile composition of Lonicera edulis wines produced with three different strains of Saccharomyces cerevisiae

Three different strains of Saccharomyces cerevisiae – D₁₅, Dibosh and 71B – were evaluated in the fermentation of Lonicera edulis wines. Volatile aromatic components were analysed by gas chromatography–mass spectrometry coupled with headspace solid‐phase microextraction. In all, 81 volatile compounds were identified in L. edulis wines, including 43, 48 and 38 individually found in wines fermented with D₁₅, Dibosh and 71B. There were 17 common volatile aromatic components found in all the three L. edulis wines. The main volatile compounds in wines fermented with D₁₅ and Dibosh yeasts were 2‐methyl‐1‐butanol (24.8%) and hexane (20.6%). Pentanol was the primary volatile aromatic compound in wines produced with S. cerevisiae 71B, accounting for 40.8% of total volatile aromatic compounds. Combining the sensory analysis, S. cerevisiae D₁₅ was suggested to be the most suitable strain for producing L. edulis wine. © 2018 The Institute of Brewing & Distilling     

Influence of organic acid concentration on survival of Listeria monocytogenes and Escherichia coli 0157:H7 in beef carcass wash water and on model equipment surfaces

Acid-adapted cultures of Escherichia coli O157:H7 and Listeria monocytogenes were inoculated in meat decontamination spray-washing runoff fluids in order to evaluate their survival and potential to form biofilms on stainless steel coupons. The cultures (10⁷ cfu ml⁻¹) and stainless steel coupons were exposed to mixtures of water and organic acid washings (composites of each of 2% acetic acid or lactic acid washings with water washings from meat decontamination in proportions of 1/9, 1/49, 1/99 [vol/vol]) or to water washings for up to 14 days at 15°C. E. coli O157:H7 formed biofilms and remained detectable (1.3 log cfu cm⁻²) on stainless steel for up to 4 d in the 1/9 dilution (pH 3.17–3.77) of the organic acid washings, and persisted throughout storage (14 d) in the 1/49 (pH 3.96–4.33) and 1/99 (pH 4.34–6.86) dilution of the organic acid washings. L. monocytogenes populations were unable to form detectable (<1.3 log cfu cm⁻²) biofilms in the 1/9 and 1/49 dilutions of both organic acid washings for up to 14 d; however, by day-14 in the 1/99 dilution of the washings, the pathogen was able to attach at detectable levels (2.7 to 3.4 logs). The pH effects of lower concentrations (1/49 or 1/99) of acidic washings decreased over time due to the formation of amine compounds produced by the natural meat flora, allowing resuscitation of the acid-stressed pathogen survivors. The resuscitation of acid-stressed pathogens may potentially enhance their survival and prevalence in biofilms and thus more attention should be focused on avoiding or minimizing the collection of decontamination runoff fluids on food contact equipment surfaces.     

Optimisation of the Amido Black assay for determination of the protein content of grape juices and wines

While the heat/chill stability of white wines cannot be predicted from the total protein concentration, this information is useful in assessing the effectiveness of fining treatments. We have adapted the Amido Black assay for use in grape juice and wine. The response of bovine serum albumin (BSA) was similar in water, model wine and model juice. The linear range of the assay (<100 mg l^?1) extends beyond protein concentrations typically found in grape juices and wines. The limit of quantification was 11.1 mg l^?1 for BSA in model wine and 7.6 mg l^?1 in model juice, while the limit of detection was found to be less than 3 mg l^?1 in either solution. In contrast to other methods of protein determination, this assay is not affected by common wine phenolic and pectic compounds or by glutathione. The mean response of BSA was similar in model juice and red and white grape juices. The mean response of BSA in red wine was lower than in white wine and model wine (p < 0.001), and there was considerable variation in response among wines. Protein concentrations determined using this method were reproducible (CV < 10%). This optimised assay can be used to monitor protein levels in grape juices and wines. © 2001 Society of Chemical Industry     

Biochemical and thermal characterization of crude exo-polygalacturonase produced by Aspergillus sojae

Crude exo-polygalacturonase enzyme (produced by Aspergillus sojae), significant for industrial processes, was characterized with respect to its biochemical and thermal properties. The optimum pH and temperature for maximum crude exo-polygalacturonase activity were pH 5 and 55 °C, respectively. It retained 60–70% of its activity over a broad pH range and 80% of its initial activity at 65 °C for 1 h. The thermal stability study indicated an inactivation energy of E_d = 152 kJ mol⁻¹. The half lives at 75 and 85 °C were estimated as 3.6 and 1.02 h, respectively. Thermodynamic parameters, ΔH^*, ΔS^* and ΔG^*, were determined as a function of temperature. The kinetic constants K_m and V_max, using polygalacturonic acid as substrate, were determined as 0.424 g l⁻¹ and 80 μmol min⁻¹, respectively. SDS-PAGE profiling revealed three major bands with molecular weights of 36, 53 and 68 kDa. This enzyme can be considered as a potential candidate in various applications of waste treatment, in food, paper and textile industries.     

Analysis of metalaxyl residues in wines by SPE in combination with HRCGC and GC/MS

Solid phase extraction (SPE) with the porous carbon sorbent CARB GR was used for the preconcentration of metalaxyl residues from a variety of Slovak grape wines with subsequent capillary GC and GC/MS analysis. Recovery was tested at various concentrations of metalaxyl in standard solutions (recovery,R92%, relative standard deviation RSD4.3%) and in wines. The value of recovery in spiked wines was dependent on the concentration (studied in the range 0.02–1.96 mg/1) and on the variety of wine (R=80–99%; RSD=2–7%). Limits of quantitation (for a sample volume of 50 ml) were determined to be 0.75 g/1 with GC-FID and 0.50 g/1 with GC/MS-ITD. Concentration levels of metalaxyl residues were determined in treated wines (with 0.25% Ridomil plus 48 WP) and a strong dependence on the protective term before the harvest was shown.     

Malolactic fermentation in four varieties of sea buckthorn (Hippophaë rhamnoides L.)

Malolactic fermentation (MLF) used in winemaking was applied to four varieties of sea buckthorn (Hippophaë rhamnoides L.). Sensory properties and chemical components of fermented and unfermented juices were studied in order to see whether the MLF can have an effect on sensory quality of sea buckthorn and if there are differences between varieties. The juices were inoculated with unadapted Oenococcus oeni at a cell density of 10⁹ CFU/mL and the fermentation was performed over 18 h at 28 °C. The fermentation decreased sourness and astringency in the samples, and fruity flavor as well as fermented flavor were increased. However, the ML reaction was different between the varieties. The size of the reaction was not proportional to the initial pH or malic acid content of the juice. Larger the ML reaction, more changes were observed in the sensory properties.     

Control of food spoiling bacteria in cooked meat products with nisin,lacticin 3147, and a lacticin 3147-producing starter culture

Nisin, in the form of the commercial product Nisaplin, and lacticin 3147 in whey powdered form were added to minced pork-meat in amounts of 0.15% (w/w) and 1.5% (w/w), respectively. The meat was cooked and inoculated with a Staphylococcus aureus strain of meat origin and a Listeria innocua strain at a level of 10⁷ or 10⁵ CFU g^–1. The batches were stored vacuum-packaged for 21 days at 8 °C. Nisin and lacticin 3147 immediately reduced the L. innocua population at the time of inoculation. Nisin showed higher inhibitory activity than lacticin 3147. During the storage period, a slight L. innocua growth was observed in the batches inoculated with the larger inoculum, and a bacteriostatic effect was observed against Listeria in the batches inoculated with 10⁵ CFU g^–1. Nisin maintained a constant S. aureus population in the cooked batch inoculated with 10⁷ CFU g^–1, although the bacteriocin was capable of reducing the amount of S. aureus by 90% in the batch inoculated with 10⁵ CFU g^–1. On the other hand, lacticin 3147 did not show an inhibitory effect against S. aureus in the cooked meat. The starter culture Lactococcus lactis DPC 303-T4 (containing the conjugative plasmid encoding production of lacticin 3147) was inoculated in a portion of a Longissimus dorsi pork muscle with brine. L. lactis DPC 303-T4 performed a good fermentation, but lacticin 3147 production was not found after 7 days at 12 °C of storage.     

Physiological features of Schizosaccharomyces pombe of interest in making of white wines

This work studies the physiology of Schizosaccharomyces pombe strain 938 in the production of white wine with high malic acid levels as the sole fermentative yeast, as well as in mixed and sequential fermentations with Saccharomyces cerevisiae Cru Blanc. The induction of controlled maloalcoholic fermentation through the use of Schizosaccharomyces spp. is now being viewed with much interest. The acetic, malic and pyruvic acid concentrations, relative density and pH of the musts were measured over the entire fermentation period. In all fermentations in which Schizo. pombe 938 was involved, nearly all the malic acid was consumed and moderate acetic concentrations produced. The urea content and alcohol level of these wines were notably lower than in those made with Sacch. cerevisiae Cru Blanc alone. The pyruvic acid concentration was significantly higher in Schizo. pombe fermentations. The sensorial properties of the different final wines varied widely.