Oxygen Requirements of Bacillus licheniformis and Bacillus subtilis in Tomato Juice; Ability to Grow in Aseptic Packages

Tomato juice was inoculated with spores of Bacillus subtilis and Bacillus licheniformis, placed in jars sealed with four polymers: oriented polypropylene (OPP), low density polypropylene with 4.5% ethyl vinyl acetate (LDPE + EVA), polyvinylidene chloride (PVDC), and polyethylene teraphthalate (PET); used in aseptic packages, serving as lids, heated in a boiling water bath for 10 min, and incubated at 35°C for up to 100 days. B. subtilis and-B. licheniformis grew at the surface of the food when OPP and LDPE + EVA were used, which caused the pH to rise above 4.6 in 60 days and above 5.0 within 100 days. The oxygen partial pressures were 0.20 and 0.18 atm per day, and the oxygen permeation ratios were 5.64 and 0.76 cc/day for LDPE + EVA and OPP, respectively.     

胀桶番茄酱中腐败微生物的分离及鉴定

为了研究胀桶番茄酱中腐败微生物种类,采用梯度稀释法、选择性培养法和划线纯化法对番茄酱中主要的腐败微生物进行分离纯化,利用形态学特征观察、16S rDNA和ITS序列分析,并结合生理生化性质对分离菌株进行鉴定。结果显示编号为B001、B002、B003、B004的4株细菌有1株厚壁类芽孢杆菌(Paenibacillus cineris)、2株蜡样芽胞杆菌(Bacillus cereus)和1株蕈状芽孢杆菌(Bacillus mycoides)。标号为F001的1株酵母为奥默毕赤酵母(Pichia kudriavzevil)。因此,胀桶番茄酱中的主要腐败微生物为厚壁类芽孢杆菌、蜡样芽胞杆菌、蕈状芽孢杆菌和奥默毕赤酵母。     

Amplification Facilitators and Pre‐Processing Methods for PCR Detection of Strictly Anaerobic Beer‐Spoilage Bacteria of the Class Clostridia in Brewery Samples

The aim of this study was to evaluate easy pre‐PCR processing procedures to allow rapid and reliable detection of strictly anaerobic beer‐spoilage bacteria throughout the brewing process by end‐point and real‐time PCR techniques. The efficiencies of the new procedures were evaluated using spiked brewery samples and specific PCRs for the target group bacteria. We found for the first time that the inclusion of 0.25% (w/v) bovine serum albumin (BSA) or 0.5% (w/v) polyvinyl pyrrolidone (PVP) in the end‐point PCR mixture reduces the inhibiting effect of brewery sample extracts (3–10%, v/v) on PCR. Membrane filtration with a PVP or a sodium tri‐polyphosphate‐EDTA wash, and cross‐flow filtration were the most promising new methods to reduce inhibitors from beer samples before cell lysis. Together with BSA, they allowed the analysis of 10% (v/v) of crude extracts instead of <3% (v/v). Moreover, we developed a one‐hour procedure to prepare target DNA from process samples containing brewer's yeast. It involved removal of inhibitors by a two‐step centrifugation followed by physical disruption of cells. The detection limit of the procedure was 10¹‐10³ CFU/mL. The developed procedures help to reduce the risk of partial or complete PCR failure due to inhibition and target DNA losses, with minimal sample handling.     

Study on ATP Production of Lactic Acid Bacteria in Beer and Development of a Rapid Pre‐Screening Method for Beer‐Spoilage Bacteria

Three beer‐spoilage strains of lactic acid bacteria (LAB), Lactobacillus brevis ABBC45, L. lindneri DSM 20690^T and L. para‐collinoides DSM 15502^T, exhibited strong ATP‐yielding ability in beer. To investigate energy sources, these beer‐spoilage strains were inoculated into beer. After the growth of the strains in beer, utilized components were determined by high performance liquid chromatography (HPLC). As a result, it was shown that citrate, pyruvate, malate and arginine were consumed by beer‐spoilage LAB strains examined in this study. The four components induced considerable ATP production even in the presence of hop compounds, accounting for the ATP‐yielding ability of the beer‐spoilage LAB strains observed in beer. We have further examined the ATP‐yielding ability of other strains of bacteria in beer. Beer‐spoilage bacteria, including Pectinatus frisingensis and P. cerevisiiphilus, showed strong ATP‐yielding abilities, whereas species frequently isolated from brewery environments exhibited low ATP‐yielding abilities. Although some of the nonspoilage LAB strains produced substantial amount of ATP in beer, the measurement of ATP‐yielding ability was considered to be useful as a rapid pre‐screening method for potential beer‐spoilage bacteria isolated from brewery environments.     

Nucleotide Sequence Identities of horA Homologues and Adjacent DNA Regions Identified in Three Species of Beer‐Spoilage Lactic Acid Bacteria

The horA homologues and adjacent DNA regions identified in beer‐spoilage Lactobacillus lindneri DSM 20690^Tand L. paracollinoides DSM15502^Twere examined and compared with the corresponding DNA region of beer‐spoilage L. brevis ABBC45, a strain in which the hop‐resistance gene horA was originally identified. The PCR analysis suggests ORFB1‐B5 regions surrounding horA are conserved in all of the strains. The nucleotide sequence comparison of the conserved DNA regions revealed extremely high levels of identities among the three beer‐spoilage strains that are not typical for distinct species. The PCR methods using primers specific to the adjacent ORFs were found to be able to differentiate beer‐spoilage Lactobacillus strains from non‐spoilers, indicating these ORFs are also useful genetic markers for determining the beer‐spoilage ability of lactobacilli. The presence or absence of the adjacent ORFs in 92 bacterial strains was completely identical with that of horA homologues, indicating the ORFB1‐B5 regions are generally conserved in beer‐spoilage Lactobacillus strains. Taken together, these results suggest the ORFB1‐B5 regions have been acquired by beer‐spoilage lactobacilli through horizontal gene transfer and provide a theoretical basis for applying a trans‐species genetic marker such as horA to deal with unencountered species of beer‐spoilage lactobacilli.     

Physiochemical Properties,Microstructure, and Probiotic Survivability of Nonfat Goats’ Milk Yogurt Using Heat‐Treated Whey Protein Concentrate as Fat Replacer

There is a market demand for nonfat fermented goats’ milk products. A nonfat goats’ milk yogurt containing probiotics (Lactobacillus acidophilus, and Bifidobacterium spp.) was developed using heat‐treated whey protein concentrate (HWPC) as a fat replacer and pectin as a thickening agent. Yogurts containing untreated whey protein concentrate (WPC) and pectin, and the one with only pectin were also prepared. Skim cows’ milk yogurt with pectin was also made as a control. The yogurts were analyzed for chemical composition, water holding capacity (syneresis), microstructure, changes in pH and viscosity, mold, yeast and coliform counts, and probiotic survivability during storage at 4 °C for 10 wk. The results showed that the nonfat goats’ milk yogurt made with 1.2% HWPC (WPC solution heated at 85 °C for 30 min at pH 8.5) and 0.35% pectin had significantly higher viscosity (P < 0.01) than any of the other yogurts and lower syneresis than the goats’ yogurt with only pectin (P < 0.01). Viscosity and pH of all the yogurt samples did not change much throughout storage. Bifidobacterium spp. remained stable and was above 10⁶CFU g^‐1 during the 10‐wk storage. However, the population of Lactobacillus acidophilus dropped to below 10⁶CFU g^‐1 after 2 wk of storage. Microstructure analysis of the nonfat goats’ milk yogurt by scanning electron microscopy revealed that HWPC interacted with casein micelles to form a relatively compact network in the yogurt gel. The results indicated that HWPC could be used as a fat replacer for improving the consistency of nonfat goats’ milk yogurt and other similar products.     

Characterization of Osmotolerant Yeasts and Yeast‐Like Molds from Apple Orchards and Apple Juice Processing Plants in China and Investigation of Their Spoilage Potential

Yeasts and yeast‐like fungal isolates were recovered from apple orchards and apple juice processing plants located in the Shaanxi province of China. The strains were evaluated for osmotolerance by growing them in 50% (w/v) glucose. Of the strains tested, 66 were positive for osmotolerance and were subsequently identified by 26S or 5.8S‐ITS ribosomal RNA (rRNA) gene sequencing. Physiological tests and RAPD‐PCR analysis were performed to reveal the polymorphism of isolates belonging to the same species. Further, the spoilage potential of the 66 isolates was determining by evaluating their growth in 50% to 70% (w/v) glucose and measuring gas generation in 50% (w/v) glucose. Thirteen osmotolerant isolates representing 9 species were obtained from 10 apple orchards and 53 target isolates representing 19 species were recovered from 2 apple juice processing plants. In total, members of 14 genera and 23 species of osmotolerant isolates including yeast‐like molds were recovered from all sources. The commonly recovered osmotolerant isolates belonged to Kluyveromyces marxianus, Hanseniaspora uvarum, Saccharomyces cerevisiae, Zygosaccharomyces rouxii, Candida tropicalis, and Pichia kudriavzevii. The polymorphism of isolates belonging to the same species was limited to 1 to 3 biotypes. The majority of species were capable of growing within a range of glucose concentration, similar to sugar concentrations found in apple juice products with a lag phase from 96 to 192 h. Overall, Z. rouxii was particularly the most tolerant to high glucose concentration with the shortest lag phase of 48 h in 70% (w/v) glucose and the fastest gas generation rate in 50% (w/v) glucose.     

Extraction of pure lycopene from industrial tomato by‐products in water using a new high‐pressure process

BACKGROUND: Lycopene, a precursor of β‐carotene with a well‐known antioxidant activity, contained in many natural products such as tomato (Lycopersicon esculentum Mill.), watermelon, red pepper and papaya, is usually recovered from natural vegetal sources using organic solvents and a purification step. In this paper an innovative process for the extraction of pure lycopene from tomato waste in water that uses the Naviglio^® extractor and water as extracting phase is presented. RESULTS: Lycopene was obtained in the all‐trans form at a very high grade of purity, not less than 98% (w/w), with an average recovery of 14% (w/w). The availability of high‐purity trans‐lycopene allowed measurement of the molar absorption coefficient. An alternative procedure for high‐performance liquid chromatographic analysis using a phenyl‐hexyl silicone phase as inverse phase and a linear gradient in water and acetonitrile is also described. CONCLUSIONS: The use of water as extracting phase considerably reduces the cost of the entire process when compared with the commonly used solvent‐based procedure or with the newer supercritical extraction process of lycopene from tomato waste. Lycopene, not soluble in water, was recovered in a quasi‐crystalline solid form and purified by solid‐phase extraction using a small amount of organic solvent. Copyright © 2008 Society of Chemical Industry This article was published online on September 15, 2008. Errors in Figures 2 ‐ 4 were subsequently identified. The publishers wish to apologise for these errors. This notice is included in the online and print versions to indicate that both have been corrected [September 19, 2008]     

Chemical,antioxidant and sensory properties of tomato‐watermelon‐pineapple blends,and changes in their total antioxidant capacity during storage

A conductometric analysis of the effect of condensate of peroxides generated during lipid oxidation in an accelerated stability test was adapted to test the hypothesis that total antioxidant capacity of tomato products would sometimes increase during processing and in storage. Tomato pulp blends made from a mixture of tomato (Lycopersicon esculentum var Roma VF), watermelon (Citrullus vulgaris var Babylack) and pineapple (Ananas comosus var Smooth cayennes) were analysed for basic quality profiles of dry matter, Brix, titratable acidity (TTA) and pH, total reducing sugars, Component antioxidants phytochemicals and total antioxidant capacity. The lowest sensory score (overall impression) of 4.80 ± 2.59 was recorded for tomato juice while, blend TWP 111p had highest score of 6.20 ± 1.99. There was significant difference (P < 0.05) in the basic quality profile of the pulp blends except for TTA values (0.37 ± 0.02 to 0.45 ± 0.05) and 2‐Furfurals (2.47 ± 0.03 to 2.71 ± 0.01). The fresh blend of 50% tomato, 25% watermelon and 25% pineapple had the highest total antioxidant capacity of 3.69 ± 0.52 mg 100 mL^?1 catechin equivalent. The total antioxidant capacity of the stored pulp increased from 2.95 ± 0.13 to 6.22 ± 0.32 mg 100 mL^?1 catechin equivalent in pasteurised TWP 211p blend by 60 days when stored at 40 °C. Total antioxidant status of tomato‐based fruit mix increased during the first 80 days.     

Influence of Lauter Turbidity on Wort Composition,Fermentation Performance and Beer Quality in Large‐Scale Trials

Different lauter turbidities (standard 43 EBC vs. turbid 82 EBC on average) were obtained by variation of the lauter procedure, particularly deep raking, in this study. The resulting worts were used for repitching the respective yeast into six subsequent fermentation cycles. The resulting beers were investigated in terms of flavour quality, flavour stability, non‐biological stability and foam stability. Worts gained from turbid lautering showed very similar analytical data compared to the controls (except for a slight but significant increase in linoleic acid). There was an improvement in fermentation performance in terms of a pH decrease and a decrease in extract. The resulting beers were quite similar, and the staling indicators increased slightly, but not significantly, due to turbid lautering. Both types of beer were evaluated on tasting as being of a high flavour quality and neither a professional panel nor a non‐professional (customer) panel was able to distinguish the difference, between standard and turbid lautering, in terms of fresh and forced aged beers. Due to turbid lautering the non‐biological stability appeared to be slightly, but not significantly, decreased while on the other hand the foam stability was significantly improved due to turbid lautering. In conclusion, fermentation performance may be improved by more turbid lautering, and the negative consequences often reported for the resulting beers appear to be overestimated, since the quality parameters of the final beers had not deteriorated significantly.     

Effects of washing procedure,particle size and dilution on the distribution between non‐washable,insoluble washable and soluble washable fractions in concentrate ingredients

The effects of washing procedure, particle size and dilution on the distribution of non‐washable (NWF), insoluble washable (ISWF) and soluble washable (SWF) fractions were studied. The effects of three washing procedures (Yang (Y), Melin (M) and in situ (IS)) on the size of NWF, ISWF and SWF in six concentrate ingredients (maize, barley, milo, peas, lupins and faba beans), ground at two different particle sizes, were compared. Method M was further developed (method SM) by reducing the dilution ratio; its effect on NWF, ISWF and SWF was compared. A new washing method was developed (method AA) which involved continuous washing of nylon bags in a centrifuge beaker; its effect on NWF, ISWF and SWF at different dilutions with water was compared with the IS, M, SM and Y methods. The effects of different dilutions on SWF and soluble true protein (STP) in six concentrate ingredients were studied. The effects of grain, washing method and particle size on the size of NWF and ISWF were significant, with significant interactions between grain and particle size, grain and washing method, particle size and washing method, but no interaction between grain type, washing method and particle size. In method Y the size of NWF was smaller than in the other methods. The results showed that, except in lupins, NWF in grains was significantly higher than in legume seeds. Increasing the particle size significantly increased NWF, whereas ISWF was decreased. The size of SWF in legume seeds was higher than in the grains. Increasing the dilution, increased STP in legume seeds, but not in grains. Copyright © 2007 Society of Chemical Industry     

In vitro gas production profile and the formation of end products from non‐ washable,insoluble washable and soluble washable fractions in some concentrate ingredients

A procedure that mimics washing in the in situ incubation technique, combined with an in vitro gas and volatile fatty acids (VFAs) production technique, was used to verify the assumption that rumen degradation behaviour of material washed out of nylon bags is instantaneous and complete. In a 6 × 4 factorial arrangement of treatments with three replicates, fractions of maize, barley, milo, yellow peas, lupins (a mixture of white and spotted lupins) and round‐seeded brown faba beans were subjected to an in vitro incubation technique. Fractions were whole (WHO), non‐washable (NWF), insoluble washable (ISWF) and soluble washable (SWF). In a manually operated in vitro fermentation system, another 24 samples of the same substrates were fermented for VFA and ammonia analysis. Except in lupins, ISWF in the concentrate ingredients was very rich in starch. SWF was relatively rich in ash, crude protein, soluble sugars, and a residual unknown fraction but contained only a negligible quantity of starch. Thus, the fermentation characteristics of ISWF were more like WHO and NWF than SWF. Total gas production of SWF was considerably lower than the other fractions. A very rapidly degradable fraction was seen in the first phase of degradation of SWF. The pattern of fermentation end‐product formation for SWF differed from that of the other fractions. Copyright © 2007 Society of Chemical Industry     

The application of near‐infrared spectroscopy in beer fermentation for online monitoring of critical process parameters and their integration into a novel feedforward control strategy

Traditional methods used in the analysis of fermentation media suffer from a number of limitations. The search for more rapid and efficient methods has led to the development and application of near‐infrared spectroscopy. Near‐infrared spectroscopy has been applied successfully in a variety of industrial processes: agricultural, food, chemical and pharmaceutical, generally in the areas of raw material quality control but also including intermediate and finished product testing. The present research explores its potential for online fermentation monitoring of total cell count (TCC), specific gravity (SG), free amino nitrogen (FAN) and percentage alcohol by volume (% v v⁻¹) in a 300 L pilot‐scale validation batch. Models that were generated from three calibration batches for each of these constituents exhibited overall favourable standard error of cross validation (SECV) and fit of predicted vs actual cross validated results (SECV, R ²): SG (0.00072, 0.995), ethanol (0.17% v v⁻¹, 0.990), FAN (16.5 mg L⁻¹, 0.886) and TCC (1.24 × 10⁶ cells mL⁻¹, 0.640). The data that was most relevant to cell metabolism was determined to be sugar consumption rate, ethanol production rate, yield of ethanol and fermentation lag time. These ‘critical performance parameters’ were incorporated into a novel feed‐forward control strategy where yeast pitching rate was modified based on values of the critical performance parameters from the previous batch. Use of this feed‐forward strategy demonstrated how brewers can utilize near‐infrared monitoring for quality assurance through early detection of shifts in fermentation performance. Copyright © 2017 The Institute of Brewing & Distilling     

3‐Chloropropane‐1,2‐diol (3‐MCPD) in Soy Sauce: A Review on the Formation,Reduction, and Detection of This Potential Carcinogen

Soy sauce, a dark‐colored seasoning, is added to enhance the sensory properties of foods. Soy sauce can be consumed as a condiment or added during the preparation of food. There are 3 types of soy sauce: fermented, acid‐hydrolyzed vegetable protein (acid‐ HVP), and mixtures of these. 3‐Chloropropane‐1,2‐diol (3‐MCPD) is a heat‐produced contaminants formed during the preparation of soy sauce and was found to be a by‐product of acid‐HVP‐produced soy sauce in 1978. 3‐MCPD has been reported to be carcinogenic, nephrotoxic, and reproductively toxic in laboratory animal testing and has been registered as a chemosterilant for rodent control. 3‐MCPD is classified as a possible carcinogenic compound, and the maximum tolerated limit in food has been established at both national and international levels. The purpose of this review is to provide an overview on the detection of 3‐MCPD in soy sauce, its toxic effects, and the potential methods to reduce its concentration, especially during the production of acid‐HVP soy sauce. The methods of quantification are also critically reviewed with a focus on efficiency, suitability, and challenges encountered in analysis.     

Measurement of High‐Pressure Carbon Dioxide Solubility in Orange Juice,Apple Juice,and Model Liquid Foods

ABSTRACT: An experimental system to measure the carbon dioxide (CO₂) solubility in liquids at different pressures was designed and tested. Pressure and temperature were controlled in the system, and the design assured an accurate measurement of solubility. Experimental measurements of CO₂ solubility were performed in pure water, model solutions (ascorbic acid–sugars–water, citric acid–sugars–water), and in commercial orange juice (OJ) and apple juice (AJ), as a function of pressure (7.58 to 15.86 MPa) at constant temperature (40 °C). Aspen simulation software was used to predict the solubility in simple cases. All experimental results and predictions from simulations were compared with literature data. Measurements of CO₂ solubility in pure water were not significantly different than the literature. CO₂ solubility (g/100 g of liquid) results in the model liquids and in the juices were lower than for pure water, due to the presence of solutes. The software simulation was able to predict the CO₂ solubility in the model systems at low pressures.     

Measurement of glucose,sucrose and lactose in food samples with enzyme‐immobilised packed‐bed column reactors integrated to an amperometric enzyme electrode

An amperometric enzyme electrode integrated with packed‐bed column reactors containing immobilised enzymes was improved to measure glucose, sucrose and lactose content of food samples with only one sampling. Performance parameters of the system were investigated on the bases of linearity, sensitivity and response time. Those values were found to be 20 mM , 24.9 nA/mM and 20 s for glucose; 20 mM , 12.0 nA/mM and 3 min for sucrose; 12 mM , 10.8 nA/mM and 4 min for lactose, respectively. Overall analysis time for three analytes with one sampling was less than 8 min without pretreatment and interference of electroactive compounds and substrates. Glucose, sucrose and lactose content of the model and food samples were measured with both the improved system and commercial enzyme kits. There was high correlation between the results. This gives us the opportunity to use the improved electrode system for determination of glucose, sucrose and lactose in food samples. Also this result was found to be very promising in extending the spectrum of detectable analytes simply by addition of new columns containing immobilised enzymes that are specific to target analytes.     

Nondestructive and Continuous Monitoring of Oxygen Levels in Modified Atmosphere Packaged Ready‐to‐Eat Mixed Salad Products Using Optical Oxygen Sensors,and Its Effects on Sensory and Microbiological Counts during Storage

The objective of this study was to determine the percentage oxygen consumption of fresh, respiring ready‐to‐eat (RTE) mixed leaf salad products (Iceberg salad leaf, Caesar salad leaf, and Italian salad leaf). These were held under different modified atmosphere packaging (MAP) conditions (5% O₂, 5% CO₂, 90% N₂ (MAPC—commercial control), 21% O₂, 5% CO₂, 74% N₂ (MAP 1), 45% O₂, 5% CO₂, 50% N₂ (MAP 2), and 60% O₂, 5% CO₂, 35% N₂ (MAP 3)) and 4 °C for up to 10 d. The quality and shelf‐life stability of all packaged salad products were evaluated using sensory, physiochemical, and microbial assessment. Oxygen levels in all MAP packs were measured on each day of analysis using optical oxygen sensors allowing for nondestructive assessment of packs. Analysis showed that with the exception of control packs, oxygen levels for all MAP treatments decreased by approximately 10% after 7 d of storage. Oxygen levels in control packs were depleted after 7 d of storage. This appears to have had no detrimental effect on either the sensory quality or shelf‐life stability of any of the salad products investigated. Additionally, the presence of higher levels of oxygen in modified atmosphere packs did not significantly improve product quality or shelf‐life stability; however, these additional levels of oxygen were freely available to fresh respiring produce if required. This study shows that the application of optical sensors in MAP packs was successful in nondestructively monitoring oxygen level, or changes in oxygen level, during refrigerated storage of RTE salad products.