Influence of sustainable packaging material and packaging conditions on physicochemical, microbiological, and sensorial properties of cheeses.

The aim of this study was to evaluate the influence of different packaging materials [standard foil: BOPP (biaxially oriented polypropylene)/PET (polyester)/PE (polyethylene) for upper layer, and APET (polyethylene terephthalate)/PE for bottom layer; foil 1: PP (polypropylene)/PET/PE/EVOH (ethylene-vinyl alcohol copolymer)/PE upper layer, and PP/PE/EVOH/PE bottom layer; foil 2: PP/PET/PE/EVOH/PE upper layer, and PA (polyamide)/EVOH/PE bottom layer; foil 3: PP/PET/PE upper layer, and PA/EVOH/PE bottom layer; foil 4: PP/PET/PE upper layer, and PA/PE bottom layer; foil 5: PP upper layer, and PP/PP bottom layer] on the quality of 3 different ripening rennet cheeses packed under different modified atmosphere (MAP) conditions as reflected in particular physicochemical, microbiological, and sensorial changes. The changes were monitored during a period of 90 d of storage at 2°C or 8°C. For Gouda cheese, CO2 content of the headspace of the packages was in the range 35% to 45%, whereas for Maasdamer and Sielski Klasyczny cheeses it was 55% to 65%. Three-way ANOVA showed that the foil type influenced the moisture content of Gouda cheese stored for 90 d at 2°C and for Sielski Klasyczny cheese at 8°C, whereas the moisture content was not dependent on MAP conditions during storage. Moreover, the foil type had a significant effect on free fatty acid changes for Gouda and Sielski Klasyczny cheeses stored at 2°C for 90 d. Sensory attributes changed significantly over storage time at 2°C for all studied cheeses as affected by foil type, whereas there was no effect of MAP conditions. In general, the cheeses packed in standard foil and foil 4 were characterized by the highest values of mean sensory attributes. Time was the most significant factor influencing most changes in physicochemical and sensory attributes of cheeses stored at 2°C and 8°C. The storage temperature did not affect the moisture of the samples during storage. In general, we found an increase in the pH value during storage regardless of storage temperature. It was possible to decrease the thickness of the packaging material from initial 103 and 250 µm (standard foil; lid and bottom, respectively) to 98 and 100 µm (foil 4) without affecting sensory attributes of the product.

Short communication: Calcium partitioning during microfiltration of milk and its influence on rennet coagulation time.

Pasteurized skim milk was subjected to (1) microfiltration (MF) at 50°C and (2) MF at 6°C after storage at 2°C. The products of these treatments were retentate (RMF50) and permeate (PMF50), and retentate (RMF6) and permeate (PMF6), respectively. Additionally, RMF50 was subjected to (3) cold MF after water dilution to produce retentate (RMF6R) and permeate (PMF6R). Calcium migration was monitored by analyzing ionic, soluble, and total calcium content in feed, retentates, and permeates. The influence of calcium partitioning and calcium addition to feed, retentates, and retentates diluted with water was determined. Without CaCl2 addition, only skim milk, RMF50, and RMF6 coagulated after rennet addition. Higher true protein and casein content of RMF50 and RMF6 resulted in shorter time of renneting. The retentates diluted with water showed no signs of coagulation within 40 min. The addition of PMF6R to RMF50 did not affect rennet coagulation time within the observed 40 min in comparison to RMF50 + water. In general, higher CaCl2 addition resulted in shorter rennet coagulation time. Special attention should be paid to calcium partitioning during membrane processing of cheesemilk. The level of calcium addition should be adopted to calcium content in such cheesemilk, which is affected by conditions of the filtration process (i.e., concentration factor and temperature).

Properties of Rennet Gels from Retentate Produced by Cold Microfiltration of Heat-Treated and Microfiltered Skim Milk.

This study investigated the production of rennet gels from ß-casein-depleted retentates obtained through cold microfiltration (MF) of skim milk (SM) that was treated beforehand to ensure microbial safety. The treatments included thermization (65 °C, 20 s), pasteurization (72 °C, 15 s), and microfiltration (50 °C; 1.4 µm pore size). The reduction in ß-casein content was 0.98, 0.51 and 0.90%, respectively. All treatments resulted in the partial aggregation of serum proteins, which were slightly concentrated in the retentates obtained post cold MF process. This aggregation, along with concentration effect, likely inhibited ß-casein dissociation from casein micelles and permeation, particularly in pasteurized milk. Renneting and coagulation properties of the retentates were comparable to those of the respective SM samples, with no significant differences in syneresis, water-holding capacity, or protein hydration. Notably, the retentate from thermized SM, which showed the best performance with the highest ß-casein reduction (0.98%), demonstrated shorter coagulation time compared to retentate from pasteurized milk or the corresponding unfiltered SM. Textural analysis revealed greater firmness, cohesiveness, and viscosity of retentate-based rennet gels compared to gels made from unfiltered SM, attributed to protein concentration during cold MF. Overall, this study successfully produced rennet gels from cold MF retentates without compromising their physicochemical properties.

Comprehensive Analysis of Yoghurt Made with the Addition of Yellow Mealworm Powder (Tenebrio molitor).

The study aimed to be able to incorporate mealworm powder into yoghurts to increase protein content. Tenebrio molitor is gaining popularity as an alternative protein source. In the face of a growing human population and the associated challenges of sustainable nutrition, mealworms offer a promising solution. The mealworm is distinguished by its high protein content and for being rich in essential amino acids, vitamins, and minerals, making it a valuable component of diet. Among others, chemical composition, colour, texture, degree of syneresis, sensory analysis, and microbiological analysis were analysed. As expected, the addition of insect powder increased the protein content from 4.91% (0 TM) to 7.41% (5 TM). It also increased the fat content from 1.67% (0 TM) to 3.88% (5 TM). Furthermore, the addition of mealworm powder resulted in a significant change in the colour of the yoghurt to a darker colour, due to the dark brown colour of the powder. Food with added edible insects is increasingly available but is not always popular due to cultural and psychological barriers. Sensory analysis of yoghurts has shown that the more powder that is added, the less appealing the product becomes and the more bitter the taste.

Influence of Different Packaging Materials on the Composition of the Headspace of Rennet Cheeses under Different Modified Atmosphere Conditions.

The aim of this study was to analyze the influence of different packaging materials on the composition of the headspace (CO2 and O2) of rennet cheeses packed in unit packaging under different modified atmosphere (MAP) conditions during a storage period of 90 days at 2 °C and 8 °C. The packaging materials comprised different combinations of BOPP-biaxially oriented polypropylene; PET-polyester; PE-polyethylene; PP-polypropylene; EVOH-ethylene-vinyl alcohol copolymer; PET-polyethylene terephthalate; and PA-polyamide. As the properties of the packaging material (foil) affect the gas conditions inside the packaging, it is important to study whether the modifications, i.e., properties and thickness, of the foils will result in significant differences in the composition of the headspace of packed cheeses. The CO2 content in the headspace of Gouda cheese packages ranged from 35% to 45%, while for Maasdamer and Sielski Klasyczny cheese, it varied between 55% and 65%. Throughout the storage period, the O2 content in the headspace of cheeses packaged in tested foils (1-5) did not exceed 0.5%. The type of foil used did not influence the modified atmosphere packaging (MAP) conditions.

Use of House Cricket (Acheta domesticus) Powder in Yoghurt Products.

This study aims to implement and increase values regarding the use of cricket powder in food. This is due to the need to increase the range of products enriched with cricket powder in order to increase the market and acceptance of insects in the diet. The work analyzed properties of yoghurt with cricket powder added (chemical composition, acidity, colour, consistency, degree of syneresis, texture and sensory analysis). Research has shown that the greater the addition of cricket powder, the higher the protein, fat and dry matter content and the lower the hardness of the yoghurt. As the content of cricket powder in yoghurt increased, the brightness (L*) and redness (a*) decreased, while the yellowness (b*) of the samples increased. A change in the colour of the yoghurt was observed with the increase in the cricket powder content; the yoghurt had a darker, browner colour. The best overall sensory rating compared to the control variant (6.4) was given to the yoghurt with 1.5% cricket powder added (5.7), while the worst rating was given to the yoghurt with 5% powder added (2 points out of 7).

Modeling the growth of Listeria monocytogenes in mold-ripened cheeses.

This study presents possible applications of predictive microbiology to model the safety of mold-ripened cheeses with respect to bacteria of the species Listeria monocytogenes during (1) the ripening of Camembert cheese, (2) cold storage of Camembert cheese at temperatures ranging from 3 to 15°C, and (3) cold storage of blue cheese at temperatures ranging from 3 to 15°C. The primary models used in this study, such as the Baranyi model and modified Gompertz function, were fitted to growth curves. The Baranyi model yielded the most accurate goodness of fit and the growth rates generated by this model were used for secondary modeling (Ratkowsky simple square root and polynomial models). The polynomial model more accurately predicted the influence of temperature on the growth rate, reaching the adjusted coefficients of multiple determination 0.97 and 0.92 for Camembert and blue cheese, respectively. The observed growth rates of L. monocytogenes in mold-ripened cheeses were compared with simulations run with the Pathogen Modeling Program (PMP 7.0, USDA, Wyndmoor, PA) and ComBase Predictor (Institute of Food Research, Norwich, UK). However, the latter predictions proved to be consistently overestimated and contained a significant error level. In addition, a validation process using independent data generated in dairy products from the ComBase database (www.combase.cc) was performed. In conclusion, it was found that L. monocytogenes grows much faster in Camembert than in blue cheese. Both the Baranyi and Gompertz models described this phenomenon accurately, although the Baranyi model contained a smaller error. Secondary modeling and further validation of the generated models highlighted the issue of usability and applicability of predictive models in the food processing industry by elaborating models targeted at a specific product or a group of similar products.

Fate of Salmonella spp. in the Fresh Soft Raw Milk Cheese during Storage at Different Temperatures.

The aim of this study was to determine the survival kinetics of Salmonella spp. in unripened, fresh raw milk cheese during storage at 5, 15 and 25 °C. Microbiological (coliforms and E. coli, S. thermophilus, Lactococcus sp., total microbial count and Enterobacteriaceae) and physicochemical (pH and aw) characteristics were also determined. Two primary models were used to estimate the kinetic parameters of Salmonella spp., namely Weibull and Baranyi and Roberts (no lag) models. Additionally, goodness-of-fit of the primary models was assessed by calculating the R-Square and mean square error. Salmonella spp. growth in the unripened raw milk cheese was inhibited during storage, but nevertheless bacteria survived at 5 °C for 33 days (2.5 log cfu/g) and 15 °C for 18 days (1.8 log cfu/g). A decrease in the number of Salmonella spp. populations from an initial concentration 6.6 log cfu/g to below a detection limit was observed at 25 °C after 7 days of storage of contaminated cheese samples. It was concluded that the storage temperature significantly influenced the inactivation rate of Salmonella spp. in fresh raw milk cheese and proceeded faster at 25 °C compared to remaining storage temperatures.

Influence of flavors and stabilizers used on the preferences and properties of aerated tvarog curd cheese.

BACKGROUND: The Polish market for tvarog (curd cheese)-based products is growing continuously. The as- sortment of these goods include products with different textures, different additives and different flavours. In developing a successful food product one should ensure consumers are sufficiently involved during the development stages. Consumer-led food product development should be a standard procedure. The study aimed to develop a new variants of aerated tvarog spreads. METHODS: The research was divided into the following steps: evaluation of consumer pref- erences (questionnaire); production of aerated tvarog cheeses (different flavor variants); physico-chemical evaluation of new products (composition, TPA test); evaluation of new products by consumers (questionnaire with a 5-point scale); sensory evaluation of new products by an expert panel (2 types of questionnaire). RESULTS: Sweet tvarog spreads were characterized by a higher degree of aeration than cheeses with a savory flavor. The savory variants had a semi-liquid consistency after aeration. This could result from the addition of salt (6%) to flavor preparation. The products stabilized by gelatine showed a higher degree of aeration than the ones with starch. The savory cheeses showed lower hardness than sweet cheeses (P < 0.05). Both consum- ers and experts gave higher marks to the sweet variants of manufactured tvarog cheeses. CONCLUSIONS: The addition of salt to savory flavor preparation probably affected the texture of these products, which was semi-liquid. Texture plays a very important role in the development of new products and affects consumers’ preferences for the product.

Modelling the Growth Rate of Listeria Monocytogenes in Cooked Ham Stored at Different Temperatures.

INTRODUCTION: The purpose of the study was to determine and model the growth rates of L. monocytogenes in cooked cured ham stored at various temperatures. MATERIAL AND METHODS: Samples of cured ham were artificially contaminated with a mixture of three L. monocytogenes strains and stored at 3, 6, 9, 12, or 15ºC for 16 days. The number of listeriae was determined after 0, 1, 2, 3, 5, 7, 9, 12, 14, and 16 days. A series of decimal dilutions were prepared from each sample and plated onto ALOA agar, after which the plates were incubated at 37ºC for 48 h under aerobic conditions. The bacterial counts were logarithmised and analysed statistically. Five repetitions of the experiment were performed. RESULTS: Both storage temperature and time were found to significantly influence the growth rate of listeriae (P > 0.01). The test bacteria growth curves were fitted to three primary models: the Gompertz, Baranyi, and logistic. The mean square error (MSE) and Akaike's information criterion (AIC) were calculated to evaluate the goodness of fit. It transpired that the logistic model fit the experimental data best. The natural logarithms of L. monocytogenes' mean growth rates from this model were fitted to two secondary models: the square root and polynomial. CONCLUSION: Modelling in both secondary types can predict the growth rates of L. monocytogenes in cooked cured ham stored at each studied temperature, but mathematical validation showed the polynomial model to be more accurate.