A Review of the Preservation of Hard and Semi-Hard Cheeses: Quality and Safety

Towards on-line cheese monitoring: Exploration of semi-hard cheeses using NIR and 1H NMR spectroscopy

This study aims to investigate the potential of using advanced spectroscopies for cheese quality monitoring. For this purpose, six semi-hard cheeses manufactured using lactic acid bacteria (LAB) and/or propionic acid bacteria (PAB) were explored using near-infrared spectroscopy (NIRS) and Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy. The spectral data were analyzed using principal component analysis for extraction of possible discriminative patterns in quality parameters. The results show that the green analytical, but primarily bulk-sensitive, NIRS method was able to discriminate the cheese varieties primarily due to differences in the first overtone CH stretching region between 1650 and 1720 nm, in particular by the lactate methylene absorption at 1674 nm. A total of 25 metabolites were identified in the 1H NMR spectra of the cheese extracts, several of which were associated with the LAB and PAB metabolic pathways. PAB-associated metabolites include propionate, acetate, and glutamate, while LAB-associated metabolites include lactate and acetoin among others.

Novel formulations for developing fresh hybrid cheese analogues utilizing fungal-fermented brewery side-stream flours

This study investigated the development of hybrid cheese analogues (HCA) made with fermented brewery side-stream ingredients (spent yeast and malt rootlets) and dairy milk. Different percentages of side-stream flours (3.5%, 5%, and 7.5%) were mixed with pasteurized milk, and the developed HCA were evaluated for their biochemical and textural properties. The addition of a fermentation step improved nutrient availability and led to pH (range 4.79-5.60) and moisture content (range 45.86%-61.29%) similar to traditional animal-based fresh cheeses (control). The inclusion of side-stream flours led to coagulation, even without rennet addition. The higher the concentration of the flour used, the faster the coagulation time, suggesting synergistic effect between the enzymes of the rennet and the enzymes present in the fermented side-stream flours. Nevertheless, textural properties were inferior compared to the control. Selected HCA formulations with added 3.5% flour exhibited increased counts of enterococci and enterobacteria cell densities, ranging from 7.28 ± 0.03 to 7.72 ± 0.09 log CFU/g and 4.90 ± 0.16 to 5.41 ± 0.01 log CFU/g, respectively. Compared to the control sample, HCA formulations exhibited higher concentrations of organic acids, peptides, and free amino acids (FAAs). Lactic acid reached up to 23.78 ± 0.94 g/kg of dry matter (DM), while the peptide area reached up to 22918.50 ± 2370.93 mL⋅AU. Additionally, the total concentration of individual FAAs reached up to 2809.74 ± 104.85 mg/kg of DM, contrasted with the control, which resulted in lower concentrations (847.65 ± 0.02 mg/kg of DM). The overall findings suggested that despite challenges in microbiological quality and textural properties, HCA produced with the inclusion of up to 3.5% brewery side-stream flours could be a sustainable solution to produce nutritious dairy alternatives.

Stability and Biaxial Behavior of Fresh Cheese Coated with Nanoliposomes Encapsulating Grape Seed Tannins and Polysaccharides Using Immersion and Spray Methods

In the food industry context, where fresh cheese stands out as a highly perishable product with a short shelf life, this study aimed to extend its preservation through multi-layer edible coatings. The overall objective was to analyze the biaxial behavior and texture of fresh cheese coated with nanoliposomes encapsulating grape seed tannins (NTs) and polysaccharides (hydroxypropyl methylcellulose; HPMC and kappa carrageenan; KC) using immersion and spray methods, establishing comparisons with uncoated cheeses and commercial samples, including an accelerated shelf-life study. NT, HPMC, and KC were employed as primary components in the multi-layer edible coatings, which were applied through immersion and spray. The results revealed significant improvements, such as a 20% reduction in weight loss and increased stability against oxidation, evidenced by a 30% lower peroxide index than the uncoated samples. These findings underscore the effectiveness of edible coatings in enhancing the quality and extending the shelf life of fresh cheese, highlighting the innovative application of nanoliposomes and polysaccharide blends and the relevance of applying this strategy in the food industry. In conclusion, this study provides a promising perspective for developing dairy products with improved properties, opening opportunities to meet market demands and enhance consumer acceptance.

A Sustainable Material for Sheep's Cheese Wedges Stored under Different Atmosphere Conditions

This study is based on the need to improve packaging sustainability in the food industry. Its aim was to assess the performance of a recyclable plastic material for semi-hard sheep's cheese wedges packaging as an alternative to conventional non-sustainable plastic materials. Four different packaging treatments (air, vacuum, and CO2/N2 gas mixtures 50/50 and 80/20% (v/v)) were studied. Changes in gas headspace composition, sensory properties, cheese gross composition, weight loss, pH, colour, and texture profile were investigated at 5 ± 1 °C storage for 56 days. The sensory analysis indicated that vacuum packaging scored the worst in paste appearance and holes, and air atmosphere the worst in flavour; it was concluded that cheeses were unfit from day 14-21 onwards. Air and vacuum packaging were responsible for most of the significant changes identified in the texture profile analysis, and most of these happened in the early stages of storage. The colour parameters a* and b* differentiated the air packaging from the rest of the conditions. As in previous studies using conventional plastic materials, modified atmosphere packaging, either CO2/N2 50/50 or 80/20% (v/v), was the most effective preserving technique to ensure the quality of this type of cheese when comparing air and vacuum packaging treatments.

Prevalence and concentration of aflatoxin M1 and ochratoxin A in cheese: a global systematic review and meta-analysis and probabilistic risk assessment

Exposure to mycotoxins such as aflatoxins can endanger human health, especially infants and children. In this study, an attempt was made to retrieved studies related to the concentration of aflatoxin M1 (AFM1) and ochratoxin A (OTA). Search was performed in international databases such as Embase, PubMed, Scopus, and Web of Science for the period 1 January 2010 to 20 February 2023. Then, the pooled concentration in the defined subgroups was calculated using meta-analysis and the health risk assessment was conducted by margin of exposure (MOEs). Thirty-one scientific papers with 34 data reports (Sample size=2,277) were included in our study. The lowest and highest prevalence of AFM1 in cheese was related to El Salvador (12.18 %) and Serbia (100.00 %). The pooled prevalence of AFM1 was 49.85 %, 95 %CI (37.93-61.78 %). The lowest and highest prevalence of OTA in cheese was related to Türkiye (6.67 %) and Italy (44.21 %). The pooled prevalence of OTA was 35.64 %, 95 %CI (17.16-56.44 %). Health risk of AFM1 revealed that except Pakistan and Iran, MOE in the other countries was lower than 10,000 for adults and also except Pakistan, MOE for other countries was lower than 10,000 for children. Health risk of OTA revealed that except Greece, MOE in the other countries was higher than 10,000 for adults and also except Germany and Greece, MOE for other countries was higher than 10,000 for children. Therefore, it is recommended to conduct control plans to reduce the concentration of mycotoxins in cheese, especially AFM1.

Effect of Biobased Cling Films on Cheese Quality: Color and Aroma Analysis for Sustainable Food Packaging

Biobased and biodegradable polymeric materials are a sustainable alternative to the conventional plastics used in food packaging. This study investigated the possible effect of biobased cling films derived from renewable and circular and sustainable sources on key cheese sensory parameters (appearance and odor) able to influence consumer acceptance or rejection of a food product over time. For this purpose, a semi-hard cheese was selected as food model and stored for 14 days at 5 °C wrapped with five cling films: two bio-plastic materials from renewable circular and sustainable sources (R-BP1 and R-BP2), one bio-plastic film from a non-renewable source (NR-BP), and two conventional cling films (LDPE and PVC). Three analytical approaches (image analysis, electronic nose, and sensory test) were applied to evaluate the variation and the acceptability in terms of appearance and odor of the cheese. In preserving cheese color, the R-BP1 and RBP2 films were comparable to LDPE film, while NR-BP film was comparable to PVC film. In terms of odor preservation, R-BP2 film was comparable to LDPE and PVC. The consumer test showed that appearance and odor scores were higher for cheeses stored in R-BP1 and R-BP2 films than NR-BP film. Moreover, in terms of odor, R-BP1 film performed better than conventional films. This study shows how biodegradable cling films from renewable circular and sustainable resources could have comparable performance to conventional plastics (LDPE and PVC) used in the food sector.

Understanding animal-based flavor generation, mechanisms and characterization: Cheddar cheese and bacon flavors

Natural animal-based flavors have great appeal to consumers and have broad applications in the food industry. In this review, we summarized findings related to bacon and Cheddar cheese flavors' components and their precursors, reaction mechanisms, influential factors, and characterization methods. The results show that free sugars, free amino acids, peptides, vitamins, lipids, and nitrites are precursors to bacon flavor. The conditions governing the formation of bacon flavor are thermally dependent, which facilitates the use of thermal food processing to generate such a flavor. For Cheddar cheese flavor, milk ingredients such as lactose, citrate, fat, and casein are reported as precursors. The optimum conditions to generate Cheddar cheese flavor from precursors are quite strict, which limits its application in food processing. As an alternative, it is more practical to generate Cheddar cheese flavor by combining key aroma compounds using thermal food processing. This review provides the food industry the comprehensive information about the generation of bacon and Cheddar cheese flavors using precursor molecules.

Changes in Sensory Properties, Physico-Chemical Characteristics, and Aromas of Ras Cheese under Different Coating Techniques

Ras cheese is one of the main hard cheeses in Egypt and is well-known worldwide. Herein, we investigated the potential effects of different coating techniques on the physico-chemical characteristics, sensory properties, and aroma-related volatile organic compounds (VOCs) of Ras cheese over a six-month ripening period. Four coating techniques were tested, including (I) uncoated Ras cheese (the benchmark control), (II) Ras cheese coated with paraffin wax (T1), (III) Ras cheese coated with a plastic film under a vacuum (PFUV; T2), and (IV) Ras cheese coated with a plastic film treated with natamycin (T3). Although none of the treatments significantly affected the salt content, Ras cheese coated with a plastic film treated with natamycin (T3) slightly reduced the moisture content over the ripening period. Moreover, our findings revealed that while T3 had the highest ash content, it showed the same positive correlation profiles of fat content, total nitrogen, and acidity % as the control cheese sample, indicating no significant effect on the physico-chemical characteristics of the coated cheese. Furthermore, there were significant differences in the composition of VOCs among all tested treatments. The control cheese sample had the lowest percentage of other VOCs. T1 cheese, coated with paraffin wax, had the highest percentage of other volatile compounds. T2 and T3 were quite similar in their VOC profiles. According to our GC-MS findings, thirty-five VOCs were identified in Ras cheese treatments after six months of ripening, including twenty-three fatty acids, six esters, three alcohols, and three other compounds identified in most treatments. T2 cheese had the highest fatty acid % and T3 cheese had the highest ester %. The development of volatile compounds was affected by the coating material and the ripening period of the cheeses, which played a major role in the quantity and quality of volatile compounds.

Novel, Edible Melanin-Protein-Based Bioactive Films for Cheeses: Antimicrobial, Mechanical and Chemical Characteristics

The cheese rind is the natural food packaging of cheese and is subject to a wide range of external factors that compromise the appearance of the cheese, including color defects caused by spoilage microorganisms. First, eight films based on whey protein isolate (WPI) coatings were studied, of which IS3CA (WPI 5% + sorbitol 3% + citric acid 3%) was selected for presenting better properties. From the IS3CA film, novel films containing melanin M1 (74 µg/mL) and M2 (500 µg/mL) were developed and applied to cheese under proof-of-concept and industrial conditions. After 40 days of maturation, M2 presented the lowest microorganism count for all the microbial parameters analyzed. The cheese with M2 showed the lowest lightness, which indicates that it is the darkest cheese due to the melanin concentration. It was found that the mechanical and colorimetric properties are the ones that contribute the most to the distinction of the M2 film in cheese from the others. Using FTIR-ATR, it was possible to distinguish the rinds of M2 cheeses because they contained the highest concentrations of melanin. Thus, this study shows that the film with M2 showed the best mechanical, chemical and antimicrobial properties for application in cheese.

Effect of Microencapsulated Basil Extract on Cream Cheese Quality and Stability

The antimicrobial and antioxidant effects of plant extracts are well known, but their use is limited because they affect the physicochemical and sensory characteristics of products. Encapsulation presents an option to limit or prevent these changes. The paper presents the composition of individual polyphenols (HPLC-DAD-ESI-MS) from basil (Ocimum basilicum L.) extracts (BE), and their antioxidant activity and inhibitory effects against strains of Staphylococcus aureus, Geobacillus stearothermophilus, Bacillus cereus, Candida albicans, Enterococcus faecalis, Escherichia coli, and Salmonella Abony. The BE was encapsulated in sodium alginate (Alg) using the drop technique. The encapsulation efficiency of microencapsulated basil extract (MBE) was 78.59 ± 0.01%. SEM and FTIR analyses demonstrated the morphological aspect of the microcapsules and the existence of weak physical interactions between the components. Sensory, physicochemical and textural properties of MBE-fortified cream cheese were evaluated over a 28-day storage time at 4 °C. In the optimal concentration range of 0.6-0.9% (w/w) MBE, we determined the inhibition of the post-fermentation process and the improvement in the degree of water retention. This led to the improvement of the textural parameters of the cream cheese, contributing to the extension of the shelf life of the product by 7 days.

Effect of Vacuum Packaging on the Biochemical, Viscoelastic, and Sensory Properties of a Spanish Cheese during Chilled Storage

The unique qualities of Spanish cheeses, such as the San Simón da Costa (SSC) cheese, are protected by the Protected Designation of Origin (PDO) status. The technological importance of chilled storage at 4 °C of vacuum-packaged (V) and natural (N) (unpackaged) cheeses was examined. For this purpose, the physico-chemical, biochemical, mechanical (puncture tests), viscoelastic (oscillatory and transient tests) and sensory properties of V and N cheeses were compared and analysed. During chilled storage, the caseins in V cheeses did not undergo proteolytic reactions. Low temperature maintained a low intensity of proteolytic phenomena for up to 6 months. Lipolysis was more intense in the N than in the V samples. The moisture content decreased in the N cheeses during chilled storage, and thus, the casein matrix concentration and ionic strength increased, resulting in an increase in the gel strength (S) parameter and complex modulus (G*), and the conformational stability-high stress amplitude (σ_max). The low and similar values of the n' and n'' exponents (mechanical spectra) and the n parameter (transient tests) indicated the high degree of the temporal stability of the cheese network in both the N and V samples, irrespective of storage time. Likewise, the similar values of the phase angle (δ) for the N and V cheeses during storage indicate energy-stable bonds in the SSC cheese matrix. The attributes of the oral tactile phase (firmness, friability, gumminess, and microstructure perception), mechanical parameters and viscoelastic moduli enabled the discrimination of the packaged and unpackaged cheeses. Cheeses chilled and stored without packaging were awarded the highest scores for sensory attributes (preference) by trained panellists.

Optimization of Modified Atmosphere Packaging for Sheep's Milk Semi-Hard Cheese Wedges during Refrigerated Storage: Physicochemical and Sensory Properties

Modified atmosphere packaging (MAP) has become a good potential strategy to retain quality throughout the shelf life of perishable foods. The aim of this work was to evaluate different packaging atmospheres on semi-hard protected designation of origin Idiazabal cheese wedges. Six different packaging treatments (air, vacuum, and CO₂/N₂ gas mixtures in the ratio of 20/80, 50/50, 80/20, and 100/0% v/v, respectively) were studied. Changes in gas headspace composition, cheese gross composition, weight loss, pH, acidity, colour, and textural and sensory properties were investigated during 56 days of refrigerated storage at 5 ± 1 °C. MAP was the most effective preserving technique compared to air- and vacuum-packaging treatments. The cheese characteristics with the greatest discriminating weight in the preservation techniques were paste appearance, holes, flavour, a* (redness) and b* (yellowness) colour parameters, and slope to hardness. Air-packaged cheeses, on 35 day, presented a mouldy flavour. Vacuum packaging affected paste appearance (greasy, plastic marks, and non-homogeneous colour) and holes (occluded and unnatural appearance) starting after 14 packaging days. MAP mixtures with CO₂ concentration between 50/50 and 80/20% CO₂/N₂ (v/v) are recommended to ensure sensory quality and stability in the distribution of these raw sheep-milk cheese wedges.

Diversity of Filamentous Fungi Associated with Dairy Processing Environments and Spoiled Products in Brazil

Few studies have investigated the diversity of spoilage fungi from the dairy production chain in Brazil, despite their importance as spoilage microorganisms. In the present study, 109 filamentous fungi were isolated from various spoiled dairy products and dairy production environments. The isolates were identified through sequencing of the internal transcribed spacer (ITS) region. In spoiled products, Penicillium and Cladosporium were the most frequent genera of filamentous fungi and were also present in the dairy environment, indicating that they may represent a primary source of contamination. For dairy production environments, the most frequent genera were Cladosporium, Penicillium, Aspergillus, and Nigrospora. Four species (Hypoxylon griseobrunneum, Rhinocladiella similis, Coniochaeta rosae, and Paecilomyces maximus) were identified for the first time in dairy products or in dairy production environment. Phytopathogenic genera were also detected, such as Montagnula, Clonostachys, and Riopa. One species isolated from the dairy production environment is classified as the pathogenic fungi, R. similis. Regarding the phylogeny, 14 different families were observed and most of the fungi belong to the Ascomycota phylum. The understanding of fungal biodiversity in dairy products and environment can support the development of conservation strategies to control food spoilage. This includes the suitable use of preservatives in dairy products, as well as the application of specific cleaning and sanitizing protocols designed for a specific group of target microorganisms.

Relationship between the Dynamics of Gross Composition, Free Fatty Acids and Biogenic Amines, and Microbial Shifts during the Ripening of Raw Ewe Milk-Derived Idiazabal Cheese

This study reports for the first time the relationship between bacterial succession, characterized by high-throughput sequencing (sequencing of V3-V4 16S rRNA regions), and the evolution of gross composition, free fatty acids (FFAs) and biogenic amines (BAs) during cheese ripening. Specifically, Idiazabal PDO cheese, a raw ewe milk-derived semi-hard o hard cheese, was analysed. Altogether, 8 gross parameters were monitored (pH, dry matter, protein, fat, Ca, Mg, P and NaCl) and 21 FFAs and 8 BAs were detected. The ripening time influenced the concentration of most physico-chemical parameters, whereas the producer mainly affected the gross composition and FFAs. Through an O2PLS approach, the non-starter lactic acid bacteria Lactobacillus, Enterococcus and Streptococcus were reported as positively related to the evolution of gross composition and FFAs release, while only Lactobacillus was positively related to BAs production. Several environmental or non-desirable bacteria showed negative correlations, which could indicate the negative impact of gross composition on their growth, the antimicrobial effect of FFAs and/or the metabolic use of FFAs by these genera, and their ability to degrade BAs. Nonetheless, Obesumbacterium and Chromohalobacter were positively associated with the synthesis of FFAs and BAs, respectively. This research work provides novel information that may contribute to the understanding of possible functional relationships between bacterial communities and the evolution of several cheese quality and safety parameters.

Hygiene and Safety of Hard Cheese Made from Raw Cows' Milk

Simple Summary

Raw cheeses have gained the preference of some consumers because of their intense and stronger taste compared with that of pasteurised cheeses. The pasteurization of raw milk causes the inactivation of the pathogenic and beneficial microorganisms of milk and of enzymes such as proteases and lipases which play a significant role in enhancing the unique flavour of raw cheeses. This study was conducted to evaluate the microbiological status of cheese made from unpasteurized cows’ milk, to examine the safety of the cheese and to observe the changes that occurred in its microbial community during ripening and storage. The microbiological quality of raw milk was found generally good and was improved throughout the experiments. For the cheese samples, a small increase in the prevalence of indicator microorganisms in curd and cheese samples was observed for the first few days, followed by a relatively stable condition as manufacturing proceeded and throughout the ripening of the final product. The outcome of our study was that the use of good-quality raw milk under sanitary conditions, the application of good manufacturing practices and a maturation period in a controlled environment were found to be the necessary prerequisites for the production of safe raw cheese products.

Abstract

This study was conducted to evaluate the microbiological status of cheese made from unpasteurized cows’ milk, to examine the safety of the cheese and to observe the changes that occurred in its microbial community during ripening and storage. Furthermore, the pH, the moisture and salt concentration were also monitored throughout processing, ripening and storage. Seven cheesemaking trials took place along with the microbiological and physicochemical analysis of the milk, curd and cheese produced. The milk used for the cheesemaking, two curd samples before the heating and two after the heating, two cheese samples at days 3, 7, 15, 30, 60 and 90 were subjected to microbiological analysis for total mesophilic bacterial count (for milk only), Enterobacteriaceae, E. coli, Staphylococcus, Salmonella, Listeria, and Clostridium. The microbiological quality of raw milk was found to be good. It was initially slightly above the EU limit but improvements associated with farm biosecurity and milking equipment hygiene led to a significantly improved milk quality. A small increase in the prevalence of indicator microorganisms in curd and cheese samples was observed for the first few days, followed by a relatively stable condition as manufacturing proceeded and throughout the ripening of the final product. In two cheesemaking trials, Clostridium perfringens and Salmonella spp. were detected, the first originating from the milk and the second from the environment. The use of good-quality raw milk under sanitary conditions, the application of good manufacturing practices and a maturation period in a controlled environment were found to be the necessary prerequisites for the production of safe raw cheese products.

Assessing Risks in Dairy Supply Chain Systems: A System Dynamics Approach

Due to the dynamic nature of the food supply chain system, food supply management could suffer because of, and be interrupted by, unforeseen events. Considering the perishable nature of fresh food products and their short life cycle, fresh food companies feel immense pressure to adopt an efficient and proactive risk management system. The risk management aspects within the food supply chains have been addressed in several studies. However, only a few studies focus on the complex interactions between the various types of risks impacting food supply chain functionality and dynamic feedback effects, which can generate a reliable risk management system. This paper strives to contribute to this evident research gap by adopting a system dynamics modelling approach to generate a systemic risk management model. The system dynamics model serves as the basis for the simulation of risk index values and can be explored in future work to further analyse the dynamic risk’s effect on the food supply chain system’s behaviour. According to a literature review of published research from 2017 to 2021, nine different risks across the food supply chain were identified as a subsection of the major risk categories: macro-level and operational risks. Following this stage, two of the risk groups identified first were integrated with a developed system dynamics model to conduct this research and to evaluate the interaction between the risks and the functionality of the three main dairy supply chain processes: production, logistics, and retailing. The key findings drawn from this paper can be beneficial for enhancing managerial discernment regarding the critical role of system dynamics models for analysing various types of risks across the food supply chain process and improving its efficiency.