Aged Cheese Research Articles

SURVEY OF SODIUM GLUCONATE CONTENT IN RETAIL CHEDDAR CHEESE

The presence of sodium gluconate in Cheddar cheese, which can be added as a processing aid during manufacture, has been shown as a contributing factor to gas production and gas defects in aged cheese. A survey of gluconate content in retail Cheddar cheese was performed. Fifty-three retail packs of cheddar cheese were purchased from stores in Utah as either blocks, shreds, sliced cheeses or individual-sized cuts and sticks. This included mild, medium and sharp cheeses. Analysis of gluconate content was performed using an enzyme assay. Levels of gluconate ≥ 0.1% were found in 7 samples with the highest level being 0.45% (wt/wt).

RESERVES AND DEVELOPMENT PROSPECTS OF ORGANIZATIONS OF THE MEAT AND DAIRY INDUSTRY OF THE VITEBSK REGION OF BELARUS

The country's meat and dairy industry has great production and innovation potential. At the same time, some organizations in the industry require rapid modernization and technical re-equipment of production processes. The work discusses measures, the implementation of which will make it possible to use the reserves available at enterprises and significantly update equipment, thereby helping to increase the economic efficiency of the functioning of organizations in the meat and dairy industry - an industry that is of great importance for the successful development of the entire Belarusian economy and is one of the sectors of specialization of the economy of the Vitebsk region. One of the possible directions of economic efficiency growth is the implementation of the meat and dairy cluster model. The purpose of creating a cluster is to centralize funds for the formation of production and market infrastructure, which will ensure the advanced development of the industry based on the implementation of a synergistic effect resulting from the combined action of economic mechanisms. In the future, different types of infrastructure, in turn, will have a positive impact on the development of the cluster itself. Almost all enterprises of the meat and dairy industry of the Vitebsk region have been modernized with the installation of automated lines, the range of aged cheeses with long shelf lives and cheeses with propionic acid bacteria has been expanded. This made it possible to significantly increase the utilization of milk processing capacities.

The distribution of rennet activity between the cheese aging process and whey is not influenced by the association of enzymes with caseins

The division of rennet in cheesemaking is split between the curd and whey, influencing the taste and texture of aged cheeses. Our study aimed to examine how raising the protein concentration in reconstituted skim milk (up to 8.8 %) affects the distribution of calf rennet activity (RA) in rennet curds produced through two methods: renting only and renneting with glucono-δ-lactone (GDL) to achieve slow acidification. The distribution of rennet activity (RA) into curds increased as the concentration of skim milk rose, ranging from 8.6 % to 29.1 % without acidification, and from 6.5 % to 19.4 % when combined with slow acidification. This increase seemed to be related to the retention of moisture and protein. Surprisingly, the concentration of residual RA in the whey (measured in international milk clotting units, IMCU/mL) remained unaffected and remained consistent with the initial IMCU/mL of milk. This suggests that the division of RA between curd and whey is not influenced by the association of enzymes with caseins (CNs). Instead, it is possible that the strength of interactions between CNs themselves plays a significant role. These findings could be valuable for research focused on enhancing the cheese aging process.

Short communication: Comparing the microbiota diversity from the core, middle part and rind of six Spanish commercial goat cheeses

The cheese core has a lower oxygen saturation and salinity and a higher acidity than the rind, but there is controversy about the incidence of such factors on the magnitude of microbial diversity. The goal of the current work was to investigate the existence of differences in α-diversity between the core, middle part, and rind of six Spanish commercial cheeses through a sequencing approach. To this end, we have collected rind, middle part, and core samples from fresh (H and M), soft semi-ripened (C and P), hard semi-ripened (B) and semi-hard aged (G) goat cheeses. After purifying deoxyribonucleic acid from these 18 samples, the V3-V4 ultravariable region of the 16S rRNA gene was sequenced. The analysis of microbial composition revealed that lactic acid bacteria from the genera Lactococcus, Lactobacillus, Streptococcus, and Leuconostoc are predominant in all six goat cheeses. Furthermore, we identified several psychrophilic taxa often associated with the post-pasteurization contamination of refrigerated milk. Comparison of three α-diversity estimators (Chao1, Shannon and Faith's phylogenetic diversity indices) of microbiota in the core, middle part, and rind of all six goat cheeses did not reveal substantial differences, being only significant (at the nominal level) the comparison of rind vs middle part for the Shannon index (P-value = 0.031). Moreover, the construction of a dendrogram based on Aitchison distances revealed that cheese samples cluster according to their manufacturing characteristics, with a clear distinction between fresh vs semi-ripened or aged cheeses. We conclude that the magnitude of microbial α-diversity in the cheese core is similar to that in the rind despite their different physicochemical attributes. This result could be because physicochemical differences between cheese compartments are often attenuated during cheese ripening.

Carbon Footprint and Carbon Sink of a Local Italian Dairy Supply Chain

The dairy industry’s contribution to global warming has been thoroughly examined. However, it is important to raise public awareness of emission hotspots and the possibility of mitigation in dairy supply chains. This study assessed the Carbon Footprint (CF) of five dairy products through a cradle-to-grave Life Cycle Assessment approach and evaluated the carbon sink potential of some practices. The functional units were 1 kg of fresh raw milk, yogurt, fresh cheese, mozzarella cheese, and aged cheese. The data collected were related to an extensive dairy farm, a cheese-factory, two markets, a delivery service, and a court of consumers. The CFs were 4.39, 5.10, 9.82, 8.40, and 15.34 kg CO2 eq. for fresh raw milk, yogurt, mozzarella cheese, fresh cheese, and aged cheese, respectively. The hotspots of the dairy supply chain considered herein refer to farm activities and energy consumption, whereas conservative agriculture practices and rotational grazing sequestered 1.60 ± 0.80 kg CO2 eq. per kg of dairy product consumed. The CF was reduced by 0.14 kg CO2 eq. for 1 kg of dairy product delivered at home compared to direct purchasing at a market. The carbon sink capacity of dairy farms appeared as a primary mean for mitigating climate change in the dairy supply chain.

The correlation between the frequent intake of dietary migraine triggers and increased clinical features of migraine (analytical cross-sectional study from Egypt)

Despite the high prevalence of primary headaches, the role of food in modifying clinical characteristics among migraine patients is often overlooked. The aim is to detect the correlation between adopting unhealthy dietary habits and migraine severity and identify foods that have a greater chance of triggering specific subtypes of migraine. The present study was a cross-sectional analytical study that was conducted at Kasralainy Hospital, Cairo University, headache clinic at Alexandria University Hospital, and Al-Azhar University Hospitals from January to June 2020. We included 124 patients fulfilling the ICHD-3 criteria for migraine. A full clinical profile for migraine headaches was reported using a headache sheet applied to the Al-Azhar University headache unit. A nutritionist obtained data collected about dietary habits using many reliable scales and questionnaires such as food frequently sheets questionnaire. Logistic regression and Pearson correlation coefficients have been used to identify foods that are more likely to be associated with increased clinical features of migraine. Our participants reported that the fried meat, fried chicken, processed meats, fava beans, falafel, aged cheese “Pottery salted cheese” and “Rummy cheese”, salted-full fatty cheese “Damietta cheese”, citrus fruits, tea, coffee, soft drinks, nuts, pickles, chocolate, canned foods, sauces, ice cream, smoked herring, in addition to the stored food in the refrigerator for many days were significantly associated with the diagnosis of chronic migraine CM compared to episodic migraine (EM). Margarine, pickles, and smoked herring were significantly associated with the diagnosis of migraine with aura (MA) compared to migraine without aura (MO). Adopting unhealthy eating habits was a more prevalent dietary consumption pattern among people with chronic migraines compared to those with episodic migraine.

Phage resistance mutations affecting the bacterial cell surface increase susceptibility to fungi in a model cheese community.

Diverse populations of bacteriophages infect and coevolve with their bacterial hosts. Although host recognition and infection occur within microbiomes, the molecular mechanisms underlying host-phage interactions within a community context remain poorly studied. The biofilms (rinds) of aged cheeses contain taxonomically diverse microbial communities that follow reproducible growth patterns and can be manipulated under laboratory conditions. In this study, we use cheese as a model for studying phage-microbe interactions by identifying and characterizing a tractable host-phage pair co-occurring within a model Brie-like community. We isolated a novel bacteriophage, TS33, that kills Hafnia sp. JB232, a member of the model community. TS33 is easily propagated in the lab and naturally co-occurs in the cheese community, rendering it a prime candidate for the study of host-phage interactions. We performed growth assays of the Hafnia, TS33, and the fungal community members, Geotrichum candidum and Penicillium camemberti. Employing Random Barcode Transposon Sequencing experiments, we identified candidate host factors that contribute to TS33 infectivity, many of which are homologs of bacterial O-antigen genes. Hafnia mutants in these genes exhibit decreased susceptibility to phage infection, but experience negative fitness effects in the presence of the fungi. Therefore, mutations in O-antigen biosynthesis homologs may have antagonistic pleiotropic effects in Hafnia that have major consequences for its interactions with the rest of the community. Ongoing and future studies aim to unearth the molecular mechanisms by which the O-antigen of Hafnia mediates its interactions with its viral and fungal partners.

Identification of bitter peptides in aged Cheddar cheese by crossflow filtration-based Fractionation, Peptidomics, statistical screening and sensory analysis

Despite bitterness being a common flavor attribute of aged cheese linked to casein-derived peptides, excessive bitterness is a sensory flaw that can lead to consumer rejection and economic loss for creameries. Our research employs a unique approach to identify bitter peptides in cheese samples using crossflow filtration-based fractionation, mass spectrometry-based peptidomics, statistics and sensory analysis. Applying peptidomics and statistical screening tools, rather than traditional chemical separation techniques, to identify bitter peptides allows for screening the whole peptide profile. Five peptides—YPFPGP (β-casein [60–65]), YPFPGPIPN (βA2-casein [60–68]), LSQSKVLPVPQKAVPYPQRDMPIQA (β-casein [165–189]), YPFPGPIHNS (βA1-casein [60–69]) and its serine phosphorylated version YPFPGPIHN[S] (βA1-casein [60–69])— demonstrated high levels of bitterness with mean bitterness intensity values above 7 on a 15-point scale. In the future, this data can be combined with the microbial and protease profile of the Cheddar samples to help understand how these factors contribute to bitter taste development.

Effect of cooking temperature on alkaline phosphatase in the production of raw-milk Pecorino cheese

Alkaline phosphatase (ALP) is a native raw-milk enzyme used in many countries as the standard assay for rapidly validating the milk pasteurization process. Due to the increased restrictions on the production or import of cheeses produced from unpasteurized milk, ALP activity (<10 mU/g) in cheese was measured as a simple and reliable method to check proper milk pasteurization in cheese for both safety inspection and trading controls. In Sicily, the artisanal cheesemaking of the Protected Denomination of Origin (PDO) semi-hard cheeses made with raw sheep's milk, includes the cooking of the curd, after the whey separation, in the wooden vat under hot Scotta-whey (≥80°C), for 3 to 4 h and finally is left to cool at ambient temperature. Thus, the temperatures adopted during cheesemaking may inactivate the ALP enzyme. To this purpose, the aim of this study was to demonstrate how different temperatures of Scotta-whey (T35, T60, T70, T80, T90, and T100) used during the second cooking of Pecorino cheeses after molding for 3 h, influence the ALP activity in fresh and 3-mo aged cheese, both at core and outside. The results highlight that the rate of reduction of ALP was greater with increasing temperature of the second cooking, in particular for T 80°C curd indicating that the use of Scotta-whey >80°C, could be a breakpoint able to reduce the ALP activity to <10 mU/g values. Different effects between the core and the outside portions of the experimental cheeses were found, with a decrease in ALP activity more on the outside than in the core portions, both in fresh and 3-mo aged cheeses, for T80, T90, and T100 treatments. Care must be taken in using the ALP to control the use of pasteurized milk in the production of PDO cheeses without considering the cheesemaking processes, such as the second cooking, which could be equal to pasteurization and an adequate interaction time/temperature can reduce the ALP activity to values comparable with cheeses produced with pasteurized milk.

Sulfur content in foods consumed in an Italian population and impact of diet quality on sulfur intake

Sulfur is an essential nutrient but data about its intake are scarce. We aimed to measure sulfur content in food samples and assess its habitual intake in relation to adherence to healthy dietary patterns in 719 Italian adults. Using a food frequency questionnaire, we estimated overall sulfur intake, and its relation with adherence to healthy dietary patterns. The highest sulfur content was found in preserved/canned fish (3.0 g/kg), seafood (2.8 g/kg), white meat (2.8 g/kg) and dairy products, particularly aged cheeses (2.1 g/kg) and lowest in fresh fruit (87 mg/kg), oils and fats (157 mg/kg), and beverages (141 mg/kg), with the exception of onion and garlic (1.3 g/kg). The mean sulfur intake in the study population was 1.1 g/day, slightly higher in men than women. The foods contributing most to sulfur intake were meat (29%) and cereals (19%), with also substantial contribution (>10%) from beverages and dairy products. Adherence to dietary patterns had little influence on sulfur intake, except for adherence to MIND diet positively and linearly associated with sulfur intake. Our study provides an updated overview of sulfur content in foods composing the Italian diet, as well as of sulfur intake in an Italian community of Northern Italy.

Thermal inactivation kinetics of Paucilactobacillus wasatchensis SH05 in whole milk

Paucilactobacillus wasatchensis is a non-starter lactic acid bacterium that causes late-blowing defects in aged cheeses, such as Cheddar. As P. wasatchensis is a less studied spoilage bacterium, this work was conducted to understand its heat resistance. Four P. wasatchensis strains were initially compared for their heat resistance, and strain SH05 was selected for the thermal inactivation kinetics experiment using aluminum thermal-death-time (TDT) disks and hot water baths. Five TDT disks, each containing 5 mL of sterilized whole milk inoculated with P. wasatchensis, were submerged in a pre-heated water bath set at respective temperatures and sampled at pre-determined time intervals. The D-values of P. wasatchensis SH05 in whole milk were D50 = 1.9, D52 = 1.0, D54 = 0.6, and D56 = 0.3 min, with the z-value of 7.7 °C.

Symptoms: Sudden Hearing Loss and Aural Fullness

Symptoms: Sudden Hearing Loss and Aural Fullness

Clinically Relevant Drug Interactions with Monoamine Oxidase Inhibitors.

Monoamine oxidase inhibitors (MAOI) are a class of drugs that were originally developed for the treatment of depression but have since been expanded to be used in management of affective and neurological disorders, as well as stroke and aging-related neurocognitive changes. Ranging from irreversible to reversible and selective to non-selective, these drugs target the monoamine oxidase (MAO) enzyme and prevent the oxidative deamination of various monoamines and catecholamines such as serotonin and dopamine, respectively. Tyramine is a potent releaser of norepinephrine (NE) and is found in high concentrations in foods such as aged cheeses and meats. Under normal conditions, NE is unable to accumulate to toxic levels due to the presence of MAO-A, an enzyme that degrades neurotransmitters, including NE. When MAO-A is inhibited, the capacity to handle tyramine intake from the diet is significantly reduced causing the brain to be vulnerable to overstimulation of postsynaptic adrenergic receptors with as little as 8-10 mg of tyramine ingested and can result in life-threatening blood pressure elevations. In addition to adverse reactions with certain foods, both older and newer MAOIs can negatively interact with both sympathomimetic and serotonergic drugs. In general, patients on a MAOI want to avoid two types of medications: those that can elevate blood pressure via sympathomimetic actions (e.g., phenylephrine and oxymetazoline) and those that can increase serotonin levels via 5-HT reuptake inhibition (e.g., dextromethorphan, chlorpheniramine, and brompheniramine). Illicit drugs that stimulate the central nervous system such as ecstasy (MDMA, 3,4-methylenedioxymethamphetamine) act as serotonin releasers. Patient involvement is also crucial to ensure any interaction within the healthcare setting includes making other providers aware of a MAOI prescription as well as avoiding certain OTC medications that can interact adversely with MAOIs.

Vestibular migraine (VM) management for an ENT surgeon - an update on diagnostic criteria and current management strategies

Overview: Vestibular migraine is a very common problem needing attention as it’s a diagnosis frequently missed. This article discusses key diagnostic indicators including ID-migraine, motion sickness, phono/photophobia. Key management options including prophylactic and abortive medications are also discussed. Findings: Using of the 3 item ID-Migraine questionnaire increases sensitivity. There is no RCT evidence that Nutraceuticals usage, restriction of MSG Caffeine Chocolates, artificial sweeteners, processed meats, alcohol and aged cheese are useful in management VM. Although beta blockers are used as prophylaxis, metoprolol may not be effective.The mainstay of abortive management is 5HT receptor agonists. Recommendations: It is necessary to raise the awareness of the diagnostic entity and necessary training and education should be given to care givers. Future research is necessary to identify therapeutic agents and lifestyle changes specifically to be effective in this condition.

Cheese quality and authenticity: new technologies help solve an age-old problem

Cheese represents a complex ecosystem of starter and non-starter bacteria, with populations changing over time as the cheese matures. Successive microbial communities, particularly in aged cheeses like cheddar, have a profound impact on the final cheese flavour and quality. Being able to accurately predict cheese ripening outcomes at an early stage, based on cost-effective analyses, would be of great benefit to cheesemakers. In the past, there has been a significant gap between microbiological and chemical information obtained from omics and its application to the cheese industry, but thanks to recent advances in omics analytical methods, computing programs and sensor technologies, this gap is narrowing.

Biogenic Amine Content in Retailed Cheese Varieties Produced with Commercial Bacterial or Mold Cultures

Biogenic amines (BAs) are considered a potential microbiological toxicological hazard in aged cheese. Risk mitigation strategies include good hygiene practice measures, thermal treatment of milk and the use of competitive dairy cultures. The aim of this study was to evaluate the amount of BAs—tryptamine, β-phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine and spermine—in the core and rind of cheeses ripened by bacteria (n = 61) and by mold cultures (n = 8). The microbial communities were counted, and the dominant lactic acid bacteria (LAB) were identified, corresponding to the BA concentrations. The total BA content was highest in the core of semi-hard cheeses (353.98 mg/kg), followed by mold cheeses (248.99 mg/kg) and lowest in hard cheeses (157.38 mg/kg). The highest amount of BAs was present in the rind of cheeses with mold (240.52 mg/kg), followed by semi-hard (174.99 mg/kg) and hard cheeses (107.21 mg/kg). Tyramine was the most abundant BA, represented by 75.4% in mold cheeses, 41.3% in hard cheese and 35% of total BAs in semi-hard cheeses. Histamine was present above the defined European maximum level (ML) of 100 mg/kg in only two semi-hard and three hard cheeses. High amount of BAs (above 600 mg/kg) in cheeses, mainly tyramine, were associated with the presence of Enterococcus durans, while negligible BA concentrations were found in cheeses ripened with Lacticaseibacillus rhamnosus, Lactococcus lactis or Lacticaseibacillus paracasei cultures. This study has shown that retailed cheese varieties produced with commercial bacterial or mold cultures have acceptable levels of biogenic amines with respect to consumers.

Comparison of Cheese Aroma Intensity Measured Using an Electronic Nose (E-Nose) Non-Destructively with the Aroma Intensity Scores of a Sensory Evaluation: A Pilot Study.

Cheese aroma is known to affect consumer preference. One of the methods to measure cheese aroma is the use of an electronic nose (e-nose), which has been used to classify cheese types, production areas, and cheese ages. However, few studies have directly compared the aroma intensity scores derived from sensory evaluations with the values of metal oxide semiconductor sensors that can easily measure the aroma intensity. This pilot study aimed to investigate the relationship between sensory evaluation scores and e-nose values with respect to cheese aroma. Five types of processed cheese (two types of normal processed cheese, one type containing aged cheese, and two types containing blue cheese), and one type of natural cheese were used as samples. The sensor values obtained using the electronic nose, which measured sample aroma non-destructively, and five sensory evaluation scores related to aroma (aroma intensity before intake, during mastication, and after swallowing; taste intensity during mastication; and remaining flavor after swallowing (lasting flavor)) determined by six panelists, were compared. The e-nose values of many of the tested cheese types were significantly different, whereas the sensory scores of the one or two types of processed cheese containing blue cheese and those of the natural cheese were significantly different. Significant correlations were observed between the means of e-nose values and the medians of aroma intensity scores derived from the sensory evaluation testing before intake, during mastication, and after swallowing. In particular, the aroma intensity score during mastication was found to have a linear relationship with the e-nose values (Pearson’s R = 0.983). In conclusion, the e-nose values correlated with the sensory scores with respect to cheese aroma intensity and could be helpful in predicting them.

Nonstarter Bacterial Communities in Aged Cheddar Cheese: Patterns on Two Timescales.

The aim of this study was to investigate the temporal stability of microbial contamination during cheddar cheese production by examining patterns of nonstarter bacteria in 60-day aged cheddar collected from the start and end of 30 consecutive production days. Further, we explored the source of these temporal microbial variations by comparing microbial communities in the aged cheese to those on food contact surfaces from a piece of cheesemaking equipment previously identified as a major source of nonstarter bacteria in the same processing environment. 16S rRNA metabarcoding and culture-based sequencing methods identified two Streptococcus sequence variants significantly associated with the end of the production day in both the aged cheese and the cheese processing environment. Closer inspection of these sequence variants in the aged cheese over the 40-day sampling period revealed sinusoidal-like fluctuations in their relative ratios, which appeared to coincide with the Lactococcus starter rotation schedule. These results demonstrate that the microbial composition of finished cheese can vary according to the timing of processing within a production day. Further, our results demonstrate that time-of-day microbial differences in cheese can result from bacterial growth on food contact surfaces and that the composition of these microbial differences is subject to change day-to-day and may be linked to routine changes in the Lactococcus starter culture. IMPORTANCE Long production schedules used in modern cheese manufacturing can create circumstances that support the growth of microorganisms in the cheese processing environment. This work demonstrates that this growth can lead to significant changes in the microbial quality of aged cheese produced later in the production day. Further, we demonstrate that the dominant bacteria associated with these microbial changes throughout production are subject to change between days and might be influenced by specific cheese manufacturing practices. These findings improve understanding of microbial contamination patterns in modern food manufacturing facilities, thereby improving our ability to develop strategies to minimize quality losses due to microbial spoilage.

Natural and Synthetic Repellents for Pest Management of the Storage Mite Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae).

Simple SummaryThe ham mite is the major pest of dry-cured hams, aged cheeses, and specialty pet foods that are high in fats and proteins. Ham mites are also known to cause allergies in some cases for humans. The toxic fumigant gas methyl bromide had been used for years to control this mite pest, but it is being phased out of use due to its impact on the protective ozone layer of the earth’s upper atmosphere. Ham producers now require alternatives to methyl bromide for controlling mites. We conducted laboratory experiments with food-safe synthetic and plant-derived chemical repellents to keep mites away from dry cured hams. Our results showed that several of these repellents could effectively prevent ham mites from contacting and staying on treated pieces of ham, and that they would readily go to untreated ham pieces when given a choice. Further experiments found that mites would not feed on nor produce offspring when held on ham pieces coated with oils from thyme, lemon grass, rose, or a mixture of naturally occurring fat molecules. Our experiments suggest that these food-safe repellents might protect dry-cured hams from mites during their time in aging rooms by application to racks on which hams are aged or to the nets and packaging in which hams are held.The fumigant pesticide methyl bromide (MB) was used for stored products, but it is now banned for most uses in many countries as an ozone-depleting substance. MB was the only pesticide used to manage the ham mite, Tyrophagus putrescentiae, which is the most significant pest of dry cured hams. Effective alternatives to MB are needed to develop integrated pest management (IPM) programs for this pest. This study evaluated plant essential oils and food-safe compounds as repellents to directly protect hams from infestation. Experiments to assess the repellency to orientation, oviposition, and population growth of mites on pieces of aged country hams were conducted. Test compounds at different concentrations were dissolved in respective solvents and compared to the solvent control. Results showed that C8910, a mixture of three short-chain fatty acids, and the sesquiterpene ketone nootkatone had repellency indices of (RI) of 85.6% and 82.3%, respectively, at a concentration of 0.1 mg/cm2, when applied to a Petri dish arena. DEET and icaridin were also tested but performed poorly with RIs below 70% even at 0.1 mg/cm2.The monoterpene alcohol geraniol had the highest RI of 96.3% at 0.04 mg/cm2. Ham pieces dipped in C8910 and nootkatone at 150 ppm each had RIs of 89.3% and 82.8%, respectively. In general, as the concentrations of test compounds increased, the numbers of eggs that were laid on these treated ham cubes decreased after the 48 h exposure time. Ham pieces dipped in different concentrations of test compounds and then inoculated with 20 adult mites showed a significant decrease in mite population growth compared to control pieces after 14 days. The results of these experiments suggest that some plant secondary metabolites and synthetic food-safe compounds could serve as potential alternatives for managing mites on hams.

Gluconate metabolism and gas production by Paucilactobacillus wasatchensis WDC04

Paucilactobacillus wasatchensis, a nonstarter lactic acid bacteria, can cause late gas production and splits and cracks in aging cheese when it metabolizes 6-carbon substrates, particularly galactose, to a 5-carbon sugar, resulting in the release of CO2. Previous studies have not explained late gas production in aging cheese when no galactose is present. Based on the genome sequence of Pa. wasatchensis WDC04, genes for potential metabolic pathways were mapped using knowledgebase predictive biology software. This metabolic modeling predicted Pa. wasatchensis WDC04 could metabolize gluconate. Gluconate contains 6 carbons, and Pa. wasatchensis WDC04 contains genes to convert it to 6-P-gluconate and then to ribulose-5-P by using 6-phosphogluconate dehydrogenase in a decarboxylating step, producing CO2 during its metabolism. The goal of this study was to determine if sodium gluconate, often added to cheese to reduce calcium lactate crystal formation, could be metabolized by Pa. wasatchensis WDC04, resulting in gas production. Carbohydrate-restricted DeMan, Rogosa, and Sharpe broth was mixed with varying ratios of ribose, sodium gluconate, or d-galactose (total added substrate content of 1% wt/vol). Oxyrase (Oxyrase Inc.; 1.8% vol/vol) was also used to mimic the anaerobic environment of cheese aging in selected tubes. Tubes were inoculated with a 4-d culture of Pa. wasatchensis WDCO4, and results were recorded over 8 d. When inoculated into carbohydrate-restricted DeMan, Rogosa, and Sharpe broth containing only sodium gluconate as the added substrate, Pa. wasatchensis WDC04 grew, confirming gluconate utilization. Of the 10 ratios used, Pa. wasatchensis WDC04 produced gas in 6 scenarios, with the most gas production resulting from the ratio of 100% sodium gluconate with no added ribose or galactose. It was confirmed that obligately heterofermentative nonstarter lactobacilli such as Pa. wasatchensis WDC04 can utilize sodium gluconate to produce CO2 gas. Addition of sodium gluconate to cheese thus becomes another risk factor for unwanted gas production and formation of slits and cracks.