Cheddar Cheese Research Articles

Parameters affecting the printability of 3D-printed processed cheese

In considering three-dimensional (3D) printing of food materials, fundamental understanding of the “printability” characteristics of different food materials is of vital importance to successfully meet user needs. In this study, a processed cheese formulation was 3D-printed with a modified 3D printer. Both intrinsic factors (i.e., pH and intact casein content) and measureable attributes (i.e., texture, printing accuracy, rheology and microstructure) were analysed. Using rheological methods, the optimal viscosity range (7.55–10.94 Pa.s) at which processed cheese will print successfully (i.e., simultaneously flow from the extrusion head uninhibited and build a layered structure) was identified. Processed cheese with a higher pH (5.8) was found to give a printed product that was significantly (P < 0.05) softer, gummier and more resilient in texture than the same recipe with a lower pH (5.4 and 5.6). Printed cheese containing exclusively fresh curd was significantly (P < 0.05) harder than that containing mild or mature Cheddar cheese. 3D printing at higher temperatures (60 °C) led to harder and more resilient cheese than printing at lower temperatures (40 °C). Overall, formulation and printing parameters for processed cheese significantly affect properties relating to “printability”.

Efficiency of removal of whey protein from sweet whey using polymeric microfiltration membranes

Our objective was to measure whey protein removal percentage from separated sweet whey using spiral-wound (SW) polymeric microfiltration (MF) membranes using a 3-stage, 3× process at 50°C and to compare the performance of polymeric membranes with ceramic membranes. Pasteurized, separated Cheddar cheese whey (1,080 kg) was microfiltered using a polymeric 0.3-μm polyvinylidene (PVDF) fluoride SW membrane and a 3×, 3-stage MF process. Cheese making and whey processing were replicated 3 times. There was no detectable level of lactoferrin and no intact α- or β-casein detected in the MF permeate from the 0.3-μm SW PVDF membranes used in this study. We found BSA and IgG in both the retentate and permeate. The β-lactoglobulin (β-LG) and α-lactalbumin (α-LA) partitioned between retentate and permeate, but β-LG passage through the membrane was retarded more than α-LA because the ratio of β-LG to α-LA was higher in the MF retentate than either in the sweet whey feed or the MF permeate. About 69% of the crude protein present in the pasteurized separated sweet whey was removed using a 3×, 3-stage, 0.3-μm SW PVDF MF process at 50°C compared with 0.1-μm ceramic graded permeability MF that removed about 85% of crude protein from sweet whey. The polymeric SW membranes used in this study achieve approximately 20%lower yield of whey protein isolate (WPI) and a 50% higher yield of whey protein phospholipid concentrate (WPPC) under the same MF processing conditions as ceramic MF membranes used in the comparison study. Total gross revenue from the sale of WPI plus WPPC produced with polymeric versus ceramic membranes is influenced by both the absolute market price for each product and the ratio of market price of these 2 products. The combination of the market price of WPPC versus WPI and the influence of difference in yield of WPPC and WPI produced with polymeric versus ceramic membranes yielded a price ratio of WPPC versus WPI of 0.556 as the cross over point that determined which membrane type achieves higher total gross revenue return from production of these 2 products from separated sweet whey. A complete economic engineering study comparison of the WPI and WPPC manufacturing costs for polymeric versus ceramic MF membranes is needed to determine the effect of membrane material selection on long-term processing costs, which will affect net revenue and profit when the same quantity of sweet whey is processed under various market price conditions.

Bio‐functional attributes in Cheddar cheese made from the milk of indigenous and crossbred cows

A study was conducted to compare the bio-functional properties between Cheddar cheese made from milk of indigenous (IMCC) and crossbred cows (CMCC). The IMCC and CMCC were prepared and analyzed for proximate composition (moisture, protein, fat, salt, ash and lactose) was found to be higher in IMCC than CMCC and bio functional properties like Angiotensin-converting enzyme (ACE) inhibition, antioxidant activity by 2,2-diphenyl 1, picrylhydrazyl (DPPH) assay and Dipeptidyl-peptidase IV (DPP-IV) inhibition activities during ripening at 7 ± 2℃. The pattern of proteolysis was found to be higher in IMCC than CMCC confirmed quantitatively by soluble nitrogen content and qualitatively by urea-PAGE (polyacrylamide gel electrophoresis). Water-soluble extract (WSE) of IMCC showed significantly higher (p < .05) ACE inhibition, DPPH scavenging, and DPP-IV inhibition activities than the extracts of CMCC during 12 months of ripening. Cheddar cheese prepared from indigenous milk produces better bio-functional properties compared to cheese prepared from crossbred milk. Practical applications In recent years, bioactive peptides are a prospective alternative to pharmaceutical drugs as they are being explored in a variety of foods for better health promotion. Consumption of bioactive peptides, derived from developed functional Cheddar cheese can play an important role in the regulation of metabolic disorders. Cheese made from indigenous milk is believed to have greater health potential but no data on cheese prepared from indigenous (Deoni) milk are available. Therefore, it is a novel work as there are hardly any studies on the Cheddar cheese made from indigenous milk and even no studies on DPP-IV inhibitory peptides, which were derived from Cheddar cheese to control the elevation of the blood glucose level. The outcome of the current study revealed that novel bio-functional cheese peptides which exert better activity and functionality that give better health benefits to consumers were found to be high in cheese prepared from indigenous milk than crossbred milk. The findings of this study may provide scope to develop functional dairy products from indigenous milk with higher health benefits.

Lipoprotein Particle Size Distributions in Response to a 6-Week Dietary Intervention Using Different Dairy Food Matrices Including Cheese and Butter

Abstract Objectives Most dietary guidelines recommend saturated fat (SFA) intakes to be &amp;lt; 10% of total energy intake, since SFA increase low-density lipoprotein cholesterol (LDL-c) levels, a known risk factor for cardiovascular disease (CVD). However, within LDL-c, small, dense LDL particles are more strongly related to CVD risk than large buoyant particles, and response to SFA vary for different foods. Dairy fat, when eaten as cheese, significantly lowers total cholesterol compared to butter. Here, we aimed to test the effect of the cheese matrix on lipoprotein particle size distribution response in overweight adults aged ≥ 50 years. Methods In this secondary analysis of a 6-week randomised parallel intervention(1); participants received ∼40g dairy fat in 1 of 4 treatments: (A) 120 g of full-fat cheddar cheese (FFCC); (B) reduced-fat cheese plus butter (RFC + B); (C) butter, calcium caseinate powder, and calcium supplement (CaCO3) (BCC); or (D) 120 g FFCC as per (A). Fasting EDTA blood samples at wk. 0 (baseline) and wk. 6 were analysed for lipoprotein particle size distribution via nuclear magnetic resonance (NMR) spectroscopy. To examine extremes in response, those with greatest reduction in LDL-c (n = 15, ‘positive’ responders) were compared to those with the greatest increase in LDL-c (n = 15, ‘negative’ responders). Results Correlation analyses between the change in cholesterol levels and change in particle size distribution suggest a relationship between change in LDL-c, HDL-c, and corresponding particle sizes, which differs dependent on the dairy fat matrix. The correlation of LDL-c and LDL particle (LDL-p) concentration weakened as less fat was present within a cheese matrix, as LDL-c decreased so did total LDL-p, due to larger LDL particles. The positive responders displayed a stronger relationship between change in cholesterol and lipoprotein levels, with the changes in cholesterol driven by the large LDL-p and large HDL-p. Conclusions Lipoprotein particle distribution is correlated with change in cholesterol levels after a 6-week intervention of dairy fat. The changes in LDL-c and HDL-c were driven by the less atherogenic, large LDL-p and large HDL-p which are inversely associated with CVD risk. The overall response in LDL-p to SFA appears to vary, dependent on the dairy food matrix in which the fat was eaten. Funding Sources Food for Health Ireland (FHI). Enterprise Ireland.

Impact of vitamin A supplementation on composition, lipolysis, stability, and sensory of refrigerated stored Cheddar cheese

In the present investigation, cheese milk was supplemented with vitamin A (retinol palmitate) at four different concentrations, i.e., 3,500, 4,000, 4,500, and 5,000 IU (T1, T2, T3, and T4), respectively. Treatment without supplementation of vitamin A was used as control. Prepared Cheddar cheese samples were stored at 4°C and further analyzed for vitamin A, organic acids, and fatty acids composition at different stages of ripening using high performance liquid chromatography and gas chromatography–mass spectrometry. Supplementation of vitamin A at all concentrations showed no significant effect on moisture, fat and protein contents of Cheddar cheese. After salting, recovery of vitamin A in control, T1, T2, T3, and T4 was 91.98%, 91.60%, 91.47%, 91.92%, and 91.56%, respectively. Storage period of 90 days significantly affected the fatty acids composition in control and all experimental samples. No significant difference was recorded in free fatty acids, peroxide value, and sensory characteristics in 90-day-old cheese samples. Practical applications Effect of vitamin A supplementation on retention and stability of Cheddar cheese was first time investigated. These results suggest that vitamin A supplemented Cheddar cheese may be prepared by supplementing the cheese milk from 3,500 to 5,000 IU retinol palmitate with acceptable sensory properties. In modern world, the Cheddar cheese prepared with vitamin A supplementation may have huge market and can be widely used in many countries worldwide as indispensable part of wide range of fast foods and also a part of daily meals in some regions.

Composition and physicochemical properties of commercial plant-based block-style products as alternatives to cheese

The global market for plant-based foods intended as alternatives to cheese products is increasing and will reach almost $4 billion by 2024. In this study, an evaluation of the composition, structure and physicochemical properties of four commercial plant-based block-style products was conducted, with results compared with those for Cheddar and processed cheeses. The plant-based products had considerably lower protein contents (0.11–3.00%) compared to the Cheddar and processed cheeses (25.04 and 18.50%, respectively). Analysis of microstructure demonstrated that the plant-based products did not have a continuous protein network, with the fat globules being stabilised by starch and other hydrocolloids. The Cheddar cheese had the highest hardness, firmness and Young's modulus values (126.8, 98.81 N and 953.3 KPa, respectively), with some of the plant-based products showing similar textural properties to the Cheddar cheese. Furthermore, rheological analysis showed that the meltability profiles of the plant-based products differed to those of Cheddar cheese. The differential scanning calorimetry thermograms showed a similar peak at ∼20 °C for all plant-based products, being different from the two peaks displayed by the dairy-based products. This study shows the complexity of the mechanisms behind the physicochemical properties of plant-based block-style alternatives to cheese and the challenges related to them.

Age and Sex Interact to Determine the Effects of Commonly Consumed Dairy Products on Postmeal Glycemia, Satiety, and Later Meal Food Intake in Adults.

Dairy consumption reduces postprandial glycemia and appetite when consumed with carbohydrates. The objective was to test the effects of frequently consumed dairy products, age, and sex on glycemia, appetite, and food intake. In a randomized, unblinded, crossover design, 30 older [60-70 y; BMI (kg/m2): 18.5-29.9] and 28 young (20-30 y; BMI: 18.5-24.9) adults consumed 500mL of a calorie-free control (water), skim milk and whole milk, 350g Greek yogurt, and 60g cheddar cheese. Food intake at an ad libitum meal was measured 120min later. Glycemia, appetite, and gastric hormone responses were measured premeal (15-120min), within-meal (120-140min), and postmeal (140-170min). Effects of treatment, age, and sex and their interactions were analyzed using ANOVA followed by Tukey's post hoc test. All forms of dairy, compared with water, decreased postmeal glycemia, premeal appetite, and meal intake (P<0.0001). Premeal glucose, insulin, and glucagon-like peptide 1 increased, and ghrelin decreased, but effects of dairy differed with age and sex. Older adults had 10% higher pre- and postmeal glucose (P<0.01). Premeal appetite suppression per 100kcal of treatments was more after yogurt than other dairy, but overall appetite suppression was less in older adults than in young adults and in males than in females (P<0.05). Pizza intake was reduced by 175kcal after yogurt and cheese and by 82kcal after milks compared to water (P<0.001). Mealtime reduction for treatment calories averaged 62% after yogurt and cheese but was less at 33% after milks (P<0.05). Compensation was less in older (33%) than in young (63%) adults (P<0.03). Dairy products consumed in usual forms before a meal stimulate metabolic responses leading to reduced premeal appetite, later food intake, and postmeal glycemia, but their effects differ in magnitude and with the sex and age of adults.

On the joint volatility dynamics in international dairy commodity markets*

The present study investigates the price (co)volatility of four dairy commodities—skim milk powder, whole milk powder, butter, and cheddar cheese—in three major dairy markets. It uses a multivariate factor stochastic volatility model for estimating the time‐varying covariance and correlation matrices by imposing a low‐dimensional latent dynamic factor structure. The empirical results support four factors representing the European Union and Oceania dairy sectors as well as the milk powder markets. Factor volatilities and marginal posterior volatilities of each dairy commodity increase after the 2006/07 global (food) crisis, which also coincides with the free trade agreements enacted from 2007 onward and EU and US liberalization policy changes. The model‐implied correlation matrices show increasing dependence during the second half of 2006, throughout the first half of 2007, as well as during 2008 and 2014, which can be attributed to various regional agricultural dairy policies. Furthermore, in‐sample value at risk measures (VaRs and CoVaRs) are provided for each dairy commodity under consideration.

Effect of Different Processing Conditions on the Physicochemical and Sensorial Characteristics of Cheddar Cheese Prepared from Different Milk Sources

Effect of Different Processing Conditions on the Physicochemical and Sensorial Characteristics of Cheddar Cheese Prepared from Different Milk Sources

Effect of lactose standardization of milk using low-concentration factor ultrafiltration: Effect of reducing the lactose-to-casein ratio on the properties of milled-curd Cheddar cheese

The pH of cheese is determined by the amount of lactose fermented and the buffering capacity of the cheese. The buffering capacity of cheese is largely determined by the protein contents of milk and cheese and the amount of insoluble calcium phosphate in the curd, which is related to the rate of acidification. The objective of this study was to standardize both the lactose and casein contents of milk to better control final pH and prevent the development of excessive acidity in Cheddar cheese. This approach involved the use of low-concentration factor ultrafiltration of milk to increase the casein content (∼5%), followed by the addition of water, ultrafiltration permeate, or both to the retentate to adjust the lactose content. We evaluated milks with 4 different lactose-to-casein ratios (L:CN): 1.8 (control milk), 1.4, 1.1, and 0.9. All cheesemilks had similar total casein (2.3%) and fat (3.4%) contents. These milks were used to make milled-curd Cheddar cheese, and we evaluated cheese composition, texture, functionality, and sensory properties over 9 mo of ripening. Cheeses made from milks with varying levels of L:CN had similar moisture, protein, fat, and salt contents, due to slight modifications during manufacture (i.e., cutting the gel at a smaller size than control) as well as control of acid development at critical steps (i.e., cutting the gel, whey drainage, salting). As expected, decreasing the L:CN led to cheeses with lower lactic acid, residual lactose, and insoluble Ca contents, as well as a substantial pH increase during cheese ripening in cheeses. The L:CN ratio had no significant effect on the levels of primary and secondary proteolysis. Texture profile analysis showed no significant differences in hardness values during ripening. Maximum loss tangent, an index of cheese meltability, was lower until 45 d for the L:CN 1.4 and 0.9 treatments, but after 45 d, all reduced L:CN cheeses had higher maximum loss tangent values than the control cheese (L:CN 1.8). Sensory analyses showed that cheeses made from milks with reduced L:CN contents had lower acidity, sourness, sulfury notes, and chewdown cohesiveness. Standardization of milk to a specific L:CN ratio, while maintaining a constant casein level in the milk, would allow Cheddar cheese manufacturers to have tighter control of pH and acidity.

Spectrophotometric method for evaluating proteolysis in cheeses and aromatic additives with a cheesy taste

The spectrophotometric method for measuring protein content can be used to evaluate the degree of proteolysis in cheeses. At a wavelength of 280 nm, tryptophan and tyrosine are absorbed, a high amount of them is found in casein, the main protein of cheese mass. It was found that the value of the absorbance coefficient of the solution of proteins extracted from flavoring additives with cheese flavor (FA) and cheeses depends on the degree of proteolysis of proteins in the cheese mass and differs in FA and different types of cheeses. The highest absorbance coefficient is observed in the FA samples A1%1cm = 10.30, in which from 65 to 81% of the protein is converted into a soluble state. In cheeses, the degree of proteolysis is from 23 to 33%, and the absorbance coefficient of solution is from 1.1 to 2.4 (with the exception of Cheddar cheese), which indicates an incomplete transition of amino acids absorbing radiation at 280 nm into the extract released from cheeses. Using the spectrophotometric method, the results of measuring the content of soluble protein in cheeses and FA, strictly correlating with the results achieved by the Kjeldahl method (R2 &gt; 0.81), can be obtained. To get reliable results of evaluating the content of water-soluble protein in cheeses, it is necessary to carry out measurements on a sample of cheeses belonging to the same species group, having the same specificity of proteolysis and slightly different absorbance coefficient between samples within the instance.

Impact of Nisin and Nisin-Producing Lactococcus lactis ssp. lactis on Clostridium tyrobutyricum and Bacterial Ecosystem of Cheese Matrices.

Clostridium tyrobutyricum spores survive milk pasteurization and cause late blowing of cheeses and significant economic loss. The effectiveness of nisin-producing Lactococcus lactis ssp. lactis 32 as a protective strain for control the C. tyrobutyricum growth in Cheddar cheese slurry was compared to that of encapsulated nisin-A. The encapsulated nisin was more effective, with 1.0 log10 reductions of viable spores after one week at 30 °C and 4 °C. Spores were not detected for three weeks at 4 °C in cheese slurry made with 1.3% salt, or during week 2 with 2% salt. Gas production was observed after one week at 30 °C only in the control slurry made with 1.3% salt. In slurry made with the protective strain, the reduction in C. tyrobutyricum count was 0.6 log10 in the second week at 4 °C with both salt concentration. At 4 °C, nisin production started in week 2 and reached 97 µg/g after four weeks. Metabarcoding analysis targeting the sequencing of 16S rRNA revealed that the genus Lactococcus dominated for four weeks at 4 °C. In cheese slurry made with 2% salt, the relative abundance of the genus Clostridium decreased significantly in the presence of nisin or the protective strain. The results indicated that both strategies are able to control the growth of Clostridium development in Cheddar cheese slurries.

Complete Genome Sequences of 10 Lactococcal Skunavirus Phages Isolated from Cheddar Cheese Whey Samples in Canada.

We report the complete genome sequences of 10 virulent phages of the Skunavirus genus (Siphoviridae) that infect Lactococcus lactis strains used for cheddar cheese production in Canada. Their linear genomes range from 28,969 bp to 31,042 bp with GC contents of 34.1 to 35.1% and 55 to 60 predicted open reading frames (ORFs).

The key aroma compounds and sensory characteristics of commercial Cheddar cheeses

To study the key aroma components and flavor profile differences of Cheddar cheese with different maturity and from different countries, the flavor components of 25 imported commercial Cheddar cheese samples in the China market were determined by gas chromatography-mass spectrometry. The quality and quantity of 40 flavor compounds were analyzed by gas chromatography-olfactometry among 71 aroma compounds determined by gas chromatography-mass spectrometry. Combined with odor activity value calculation, principal component analysis (PCA) was conducted to analyze the relationship among 26 flavor compounds with odor activity values >1 and the maturity of Cheddar cheese. The PCA results showed significant differences between the group of mild Cheddar cheese and the groups of medium Cheddar cheese and mature Cheddar cheese, and no significant differences were observed between medium Cheddar cheese and mature Cheddar cheese. According to the results of PCA and consumers' preference test, representative Cheddar cheese samples with different ripening times were selected for the flavor profile analysis. Partial least squares regression analysis was conducted to obtain the relationship between sensory properties and flavor compounds of different Cheddar cheeses. Based on partial least squares regression analysis, 1-octen-3-one, hexanal, acetic acid, 3-methylindole, and acetoin were positively correlated with milky, sour, and yogurt of mild Cheddar cheese. Dimethyl trisulfide, phenylacetaldehyde, ethyl caproate, octanoic acid, and furaneol and other compounds were positively correlated with fruity, caramel, rancid, and nutty notes of the medium and mature Cheddar cheeses.

Population dynamics of coliforms in a commercial Cheddar cheese production facility

The detection of coliforms in young cheese is a potential indication of undesirable microbial growth within the processing environment. The aim of this study was to investigate sources and conditions that lead to the intermittent detection of coliforms (1-3 log cfu/g) in young Cheddar cheese at a single commercial facility. Analysis of historical production data, in combination with iterative investigative sampling events, was performed to determine coliform levels in milk, whey, curd, and surfaces at the beginning, middle, and end of the production day. After sanitation, conveyor belt pieces from the draining and matting conveyor (DMC) were collected and evaluated for bacterial survivors using culture-based methods and scanning electron microscopy. Production data analysis indicated that cheese produced later in the production day (≥16 h) was significantly more likely to test positive for coliforms than cheese made earlier in the production day (<12 h). Enumeration of coliforms in raw and heat-treated milk demonstrated that the subpasteurization thermal treatment (67-70°C, 26-28 s) was effective at reducing, but not eliminating, coliforms. Repeated sampling identified the DMC, particularly the drain belt and belt 1, as a critical area that supported coliform growth during the production day. Coliform levels in whey entering the weir maintained a level of <1 cfu/mL throughout production; however, coliform levels in whey below the drain belt increased from <1 cfu/mL at midday (8 h) to 5.04 log cfu/mL by the end of the production day (~18 h). Routine sanitation inside the DMC resulted in undetectable coliform levels on easily accessible surfaces. However, enrichment and scanning electron microscopy of belt sections revealed pockets of viable coliforms and other bacteria in cracks and defects in conveyor belts, indicating that sanitation did not eliminate all viable bacteria. Low levels of coliforms are present in heat-treated milk and survive sanitation in the DMC and could serve as the initial seed for high levels of coliforms at the end of the production day.

Determination of the efficiency of removal of whey protein from sweet whey with ceramic microfiltration membranes

Our research objective was to measure percent removal of whey protein from separated sweet whey using 0.1-µm uniform transmembrane pressure ceramic microfiltration (MF) membranes in a sequential batch 3-stage, 3× process at 50°C. Cheddar cheese whey was centrifugally separated to remove fat at 72°C and pasteurized (72°C for 15 s), cooled to 4°C, and held overnight. Separated whey (375 kg) was heated to 50°C with a plate heat exchanger and microfiltered using a pilot-scale ceramic 0.1-µm uniform transmembrane pressure MF system in bleed-and-feed mode at 50°C in a sequential batch 3-stage (2 diafiltration stages) process to produce a 3× MF retentate and MF permeate. Feed, retentate, and permeate samples were analyzed for total nitrogen, noncasein nitrogen, and nonprotein nitrogen using the Kjeldahl method. Sodium dodecyl sulfate-PAGE analysis was also performed on the whey feeds, retentates, and permeates from each stage. A flux of 54 kg/m2 per hour was achieved with 0.1-µm ceramic uniform transmembrane pressure microfiltration membranes at 50°C. About 85% of the total nitrogen in the whey feed passed though the membrane into the permeate. No passage of lactoferrin from the sweet whey feed of the MF into the MF permeate was detected. There was some passage of IgG, bovine serum albumen, glycomacropeptide, and casein proteolysis products into the permeate. β-Lactoglobulin was in higher concentration in the retentate than the permeate, indicating that it was partially blocked from passage through the ceramic MF membrane.

Growth potential and biofilm development of nonstarter bacteria on surfaces exposed to a continuous whey stream

Commercial Cheddar cheese production uses an automated, continuous production system that provides favorable conditions for specific undesirable bacterial subpopulations in certain sections of the processing system. The draining and matting conveyor (DMC) is a large, fully enclosed series of conveyor belts that separates curd and whey on the first drain belt and supports the cheddaring process in subsequent sections. In a previous study, we demonstrated that coliforms increase in the draining section of the DMC (pH 6.0-6.3, 36°C) over a typical 18-h production shift and can lead to detectable coliforms in finished cheese. Sampling at the commercial plant indicated 2 sources of very low levels of coliforms: (1) subpasteurized whey and curd entering the DMC and (2) surfaces in the DMC after sanitation. Mitigation of these sources would require different approaches. The aim of this study was to investigate whether naturally low levels of coliforms in whey could increase in the bulk liquid and attach to different surface materials within 18 h. A laboratory-scale system was created to mimic the conditions of the initial draining section of the DMC and consisted of single-pass, naturally contaminated whey (pH 6.3, 35°C) flowing through a bioreactor (1.11 L/h) containing coupons of surface types found in the DMC (stainless steel and polypropylene). Whey inside the bioreactor chamber and surface coupons were enumerated for bacterial subpopulations on selective media for planktonic and attached bacteria, respectively, at 0, 12, 15, and 18 h. Bacterial isolates were identified by 16S rDNA sequencing. Nonstarter bacteria present in the whey at 0 h included coliforms (Enterobacter), Pseudomonas, and Acinetobacter (0.80, 2.55, and 2.32 log cfu/mL, respectively), with each increasing significantly in whey (6.18, 7.00, and 5.89 log cfu/mL) and on coupons (5.20, 6.85, and 5.29 log cfu/cm2, respectively) after 18 h in the continuous flowing system. Scanning electron microscopy confirmed bacterial attachment on both surfaces, with early biofilm development evident on polypropylene coupons by 18 h. Results from this laboratory-scale study demonstrated that naturally low levels of coliforms entering the DMC in the whey could replicate within the conditions of the draining section of the DMC to the levels found in the commercial production environment.

Optimizing the acceleration of Cheddar cheese ripening using response surface methodology by microbial protease without altering its quality features

Cheddar cheese proteolysis were accelerated employing Penicillium candidum PCA1/TT031 protease into cheese curd. In the present study, several of the significant factors such as protease purification factor (PF), protease concentration and ripening time were optimized via the response surface methodology (RSM). The ideal accelerated Cheddar cheese environment consisted of 3.12 PF, 0.01% (v/v) protease concentration and 0.6/3 months ripening time at 10 °C. The RSM models was verified to be the most proper methodology for the maintain of chosen Cheddar cheese. Under this experimental environment, the pH, acid degree value (ADV), moisture, water activity (aw), soluble nitrogen (SN)%, fat and overall acceptability were found to be 5.4, 6.6, 35%, 0.9348, 18.8%, 34% and 13.6, respectively of ideal Cheddar cheese. Furthermore, the predicted and experimental results were in significant agreement, which confirmed the validity and reliability of the suggested method. In spite of the difference between the ideal and commercial Cheddar cheese in the concentration of some of amino acids and free fatty acids, the sensory evaluation did not show any significant difference in aroma profile between them.

Histamine-forming ability of Lentilactobacillus parabuchneri in reduced salt Cheddar cheese

Lentilactobacillus parabuchneri, a member of the non-starter microbiota in cheese, was recently associated with fast and effective histamine-formation ability, a safety issue. The present study was performed to investigate Lentilactobacillus parabuchneri KUH8, a histamine-producer (HP) in reduced-salt Cheddar cheese. Four cheeses were manufactured: 1) normal-salt (NS); 2) reduced-salt (RS); 3) normal-salt with HP (NS+HP); 4) reduced-salt with HP (RS+HP). Two replicates were produced with milk from the same batch, and the cheeses ripened at 10 and 15 °C. Cheeses were sampled immediately after manufacture and after 1, 3 and 6 months of ripening. Ultra-high-performance-liquid chromatography indicated that with the HP, histamine reached higher levels in reduced-salt cheeses (3.5–3.7% S/M) at 15 °C (86, 1112, 2149 and 3149 mg kg−1), compared to normal-salt cheeses (5.4–6.3% S/M) at 10 °C (78, 584, 593 and 1389 mg kg−1), at each respective cheese-sampling point. Higher salt-content reduced the growth rate of non-starter microbiota, but after six months the levels in all cheeses were similar, according to the ripening temperature: at 10 °C (8.05–8.30 log10 cfu g−1), and at 15 °C (6.00–6.94 log10 cfu g−1). A correlation between increased histamine levels, non-starter-cell development and pH was found. This study highlights the importance of normal-salt content and low-ripening temperature as measures to control histamine-formation and to improve safety in cheese.

Proteolysis and ACE-inhibitory peptide profile of Cheddar cheese: Effect of digestion treatment and different probiotics

Proteolysis degree, ACE-inhibitory (ACE-I) activity, water-soluble peptide profiles of Cheddar cheese with different probiotics were determined during digestion period and were comprehensively compared to evaluate the influence of digestion and the addition of different probiotics. After digestion, further hydrolysis of protein led to the production of more low molecular weight peptides, and ACE-I peptides with higher activity were released. ACE-I activity of Cheddar cheese with Lactobacillus helveticus (B4, 86.06%) was significantly (P < 0.05) higher than other cheese groups. Three ACE-I peptides were uniquely presented in B4 before digestion and more new ACE-I peptides were released after digestion. Meanwhile, cheese with Lactobacillus rhamnosus was more likely to produce anti-digestion ACE-I peptides. Most of ACE-I peptides come from β-casein. Hydrophobic amino acids Val, Phe, Pro, Tyr, Leu, and basic amino acids Arg, Lys at the C-terminal were more responsible for the formation of ACE inhibitory peptides that resist digestion. This research provides the basis to increase the exploitation of the health benefits of Cheddar cheese with probiotic.