Cheese-making Industry Research Articles

Isolation and identification of milk-clotting proteases from Prinsepia utilis Royle and its application in cheese processing

The aim of this study was to isolate and identify the main milk-clotting proteases from Prinsepia utilis Royle. Protein isolates obtained using precipitation with 20 %–50 % ammonium sulfate (AS) showed higher milk-clotting activity (MCA) at 154.34 + 0.35 SU. Two milk-clotting proteases, namely P191 and P1831, with molecular weight of 49.665 kDa and 68.737 kDa, respectively, were isolated and identified using liquid chromatography-mass spectrometry (LC-MS/MS). Bioinformatic analysis showed that the two identified milk-clotting proteases were primarily involved in hydrolase activity and catabolic processes. Moreover, secondary structure analysis showed that P191 structurally consisted of 40.85 % of alpha-helices, 15.96 % of beta-strands, and 43.19 % of coiled coil motifs, whereas P1831 consisted of 70 % of alpha-helices, 7.5 % of beta-strands, and 22.5 % of coiled coil motifs. P191 and P1831 were shown to belong to the aspartic protease and metalloproteinase types, and exhibited stability within the pH range of 4–6 and good thermal stability at 30–80 °C. The addition of CaCl2 (<200 mg/L) increased the MCA of P191 and P1831, while the addition of NaCl (>3 mg/mL) inhibited their MCA. Moreover, P191 and P1831 preferably hydrolyzed kappa-casein, followed by alpha-casein, and to a lesser extent beta-casein. Additionally, cheese processed with the simultaneous use of the two proteases isolated in the present study exhibited good sensory properties, higher protein content, and denser microstructure compared with cheese processed using papaya rennet or calf rennet. These findings unveil the characteristics of two proteases isolated from P. utilis, their milk-clotting properties, and potential application in the cheese-making industry.

Screening of Aroma-Producing Performance of Anticlostridial Lacticaseibacillus casei Strains

AbstractThe cheesemaking industry is increasingly interested in using adjunct cultures with potential aromatic and anticlostridial activities. In this study, 34 Lb. paracasei and 2 Lb. rhamnosus strains were isolated from a semi-hard cheese and characterized for their proteolytic, esterase, and anticlostridial activity. Moreover, the strains were inoculated in a curd-based medium and the volatile compounds in the headspace of samples were evaluated by solid-phase microextraction–GC–MS analysis. Proteolytic activity was present in 30 strains, whereas only one Lb. paracasei strain showed esterase activity. All strains inhibited Cl. sporogenes, Cl. beijerinckii, and Cl. butyricum, and 18 isolates inhibited at least one Cl. tyrobutyricum strain. Principal component analysis and clustering analysis based on the volatilome grouped strains into three groups. One of these groups was characterized by high amounts of acids and esters and clustered with control samples inoculated with commercial starter cultures, suggesting similarity in the aroma profile. Strains belonging to this group with inhibitory effects against Cl. tyrobutyricum might be exploited as autochthonous adjunct cultures for the reduction of late-blowing defects in semi-hard cheeses.

Анализ и перспективы развития отрасли сыроделия: региональный аспект

Cheese is a unique product of animal origin. The history of cheese-making dates back millennia, and every nation has its own traditional cheese formulations. Recent decades have seen a growing public interest in craft cheese-making and national cheese-making. As a multinational country, Russia boasts a wide range of traditional cheeses. However, the domestic cheese market belongs mainly to such popular foreign cheese sorts as Mozzarella, Camembert, Tilsit, Brie, etc. The steady increase in consumer demand for cheese products encourages cheese-makers to expand their product range, and, in their search for new formulations, they often appeal to traditional cheeses, e.g., those produced in the Altai Region. Despite this trend, the average annual per capita consumption of cheese in Russia remains at 6.5 kg while in some other developed countries this criterion is as high as 16 kg. The present development assessment of the Russian cheese-making industry showed a severe shortage in domestic direct-application starter cultures. Russian cheese-makers prefer imported recombinant milk-clotting enzymes, which significantly hampers industrial development. A new domestic production could provide enough raw materials to satisfy the growing demand for rennet products. At present, the raw milk production capabilities cannot meet the ever-increasing needs. The domestic market of dairy raw materials is dominated by cow milk while goat milk and sheep milk are associated mainly with soft cheeses, and buffalo milk occupies a very narrow sector of craft cheese-making.

Correlations of goat milk coagulation properties between dams and daughters

Goat milk coagulation properties (gMCP) are important trait for the cheesemaking industry but are rarely included in national breeding programs. In the present study, we monitored goat milk quality traits and gMCP of Slovenian Alpine goats within a single flock (N = 77), reared in the same common environment over three-year period. In addition, using pedigree data, we looked for correlations among dams, daughters (N = 32 pairs) and gMCP. Traditional gMCP measurements were introduced into a 4-parameter curd firmness over time (CFt) model. Several gMCP parameters were associated with parity and stage of lactation. Most notably, estimated rennet coagulation time (RCTeq), curd firmness at 15 (a15eq) and 20 min (a20eq) after rennet addition were strongly correlated between dams and their daughters. These results support further research of genetic parameters for gMCP and the inclusion of breeding value predictions for gMCP in national breeding programs.

Slower proteolysis in Cheddar cheese made from high-protein cheese milk is due to an elevated whey protein content.

A growing number of companies within the cheese-making industry are now using high-protein (e.g., 4-5%) milks to increase cheese yield. Previous studies have suggested that cheeses made from high-protein (both casein and whey protein; WP) milks may ripen more slowly; one suggested explanation is inhibition of residual rennet activity due to elevated WP levels. We explored the use of microfiltration (MF) to concentrate milk for cheese-making, as that would allow us to concentrate the casein while varying the WP content. Our objective was to determine if reducing the level of WP in concentrated cheese milk had any impact on cheese characteristics, including ripening, texture, and nutritional profile. Three types of 5% casein standardized and pasteurized cheese milks were prepared that had various casein:true protein (CN:TP) ratios: (a) control with CN:TP 83:100, (b) 35% WP reduced, 89:100 CN:TP, and (c) 70% WP reduced, 95:100 CN:TP. Standardized milks were preacidified to pH 6.2 with dilute lactic acid during cheese-making. Composition, proteolysis, textural, rheological, and sensory properties of cheeses were monitored over a 9-mo ripening period. The lactose, total solids, total protein, and WP contents in the 5% casein concentrated milks were reduced with increasing levels of WP removal. All milks had similar casein and total calcium levels. Cheeses had similar compositions, but, as expected, lower WP levels were observed in the cheeses where WP depletion by MF was performed on the cheese milks. Cheese yield and nitrogen recoveries were highest in cheese made with the 95:100 CN:TP milk. These enhanced recoveries were due to the higher fraction of nitrogen being casein-based solids. Microfiltration depletion of WP did not affect pH, sensory attributes, or insoluble calcium content of cheese. Proteolysis (the amount of pH 4.6 soluble nitrogen) was lower in control cheeses compared with WP-reduced cheeses. During ripening, the hardness values and the temperature of the crossover point, an indicator of the melting point of the cheese, were higher in the control cheese. It was thus likely that the higher residual WP content in the control cheese inhibited proteolysis during ripening, and the lower breakdown rate resulted in its higher hardness and melting point. There were no major differences in the concentrations of key nutrients with this WP depletion method. Cheese milk concentration by MF provides the benefit of more typical ripening rates.

A Low-Temperature and Low-Pressure Distillation Plant for Dairy Wastewater

The paper investigates an alternative treatment plant for the typical wastewater effluent of a cheese-making industry, mainly composed of acid or sweet whey mixed with washing-water. Two variable parameters have been considered during the tests: four treatment temperatures (39, 46, 53 and 60 °C) and three solid content values (30%, 50% and 70%) of the concentrated product. The minimum and maximum values of the removal efficiency (pollutant amount into concentrate related to raw whey) range from 94.6% to 97.7% for conductivity, from 98.3% to 99.5% for BOD5, from 98.7% to 99.6% for COD and from 98.2% to 99.3% for Total Nitrogen. The plant capacity ranges from about 2 L/h (at 39 °C) to 6 L/h (at 60 °C) of processed whey. On the basis of the experimental findings, the proposed purification technology has demonstrated its suitability both to purify the effluent wastewater and to recover high-quality products (e.g., whey protein concentrate, lactose), thanks to its low thermal damage on the treated product and to its relatively low energy consumption from 0.4 kWh/L (at 60 °C) to 1.0 kWh/L (at 39 °C) of processed whey, with a Coefficient of Performance from approximately 0.6 up to 1.5.

Obtaining of Recombinant Camel Chymosin and Testing Its Milk-Clotting Activity on Cow's, Goat's, Ewes', Camel's and Mare's Milk.

In the cheese-making industry, commonly chymosin is used as the main milk-clotting enzyme. Bactrian camel (Camelus bactrianus) chymosin (BacChym) has a milk-clotting activity higher than that of calf chymosin for cow's, goat's, ewes', mare's and camel's milk. A procedure for obtaining milk-clotting reagent based on recombinant camel chymosin is proposed here. Submerged fermentation by a recombinant yeast (Pichia pastoris GS115/pGAPZαA/ProchymCB) was implemented in a 50 L bioreactor, and the recombinant camel chymosin was prepared successfully. The activity of BacChym in yeast culture was 174.5 U/mL. The chymosin was concentrated 5.6-fold by cross-flow ultrafiltration and was purified by ion exchange chromatography. The activity of the purified BacChym was 4700 U/mL. By sublimation-drying with casein peptone, the BacChym powder was obtained with an activity of 36,000 U/g. By means of this chymosin, cheese was prepared from cow's, goat's, ewes', camel's and mare's milk with a yield of 18%, 17.3%, 15.9%, 10.4% and 3%, respectively. Thus, the proposed procedure for obtaining a milk-clotting reagent based on BacChym via submerged fermentation by a recombinant yeast has some prospects for biotechnological applications. BacChym could be a prospective milk-clotting enzyme for different types of milk and their mixtures.

Production of a novel milk-clotting enzyme from solid-substrate Mucor spp. culture.

Calf rennet has been traditionally used for cheese making all over the world since ancient times. It is primarily a type of aspartic protease. Calf rennet, also known as chymosin, is considered the best milk coagulant in cheese manufacturing. Its usage and demand are increasing day by day in the food industry; however, some ethical issues are also related since it is naturally present in the calf's stomach and obtained by the slaughtering of young animals. Therefore, researchers are trying to introduce some new and better alternatives for chymosin in the food industry. Mucor racemosus f. racemosus CBS 381, Mucor racemosus DSM 62760, and Aspergillus oryzae were cultivated by solid substrate fermentation using the design of experiment (DoE) (MODDE; Umetrics, Sweden) to optimize and analyze the various combinations of different factors and responses (milk-clotting activity, proteolytic activity, specific activity). Based on the analysis of the screening and optimization results, Mucor racemosus CBS 381 was found to be the potential strain in terms of high production of aspartic protease, as well as had high milk-clotting activity under a solid-state fermentation system. However, molasses and casein were determined to be significant carbon and nitrogen sources, respectively, under conditions such as 70% moisture content and 25°C temperature. The molecular weight of the enzyme (Mucor CBS 381) is ∼30 KDa and it exhibits maximum activity at pH 4.8 at 45°C. The investigated enzyme was pronounced as thermal-sensitive and lost activity completely after 10 min incubation at 55°C. The remarkable qualities of the studied enzyme, such as cost-effective production, milk-clotting and proteolytic activity make Mucor racemosus CBS 381 a promising alternate to calf chymosin in the cheese-making industry. PRACTICAL APPLICATION: The milk-clotting enzyme (aspartic protease) produced by the Mucor racemosus is the alternative to calf chymosin. It can be used to produce cheese on the industrial level with some desired properties such as good taste and texture that includes gumminess. Nowadays, consumers prefer products that do not involve any animal cruelty whereas a huge group of consumers oppose the use of genetically modified enzymes. Therefore, the enzyme by Mucor racemosus would produce the cheese that is going to meet the demands of various types of cheese consumers.

Identification, structure, and caseinolytic properties of milk-clotting proteases from Moringa oleifera flowers

The protein extract of Moringa oleifera flowers is reported to have milk-clotting activity (MCA), but information regarding its protease is unclear. In this study, two milk-clotting proteases (MoFP 12 and MoFP 13) with molecular weights of 42.304 kDa and 31.741 kDa, respectively, were isolated and identified from M. oleifera flowers using liquid chromatography-mass spectrometry (LC-MS/MS). Bioinformatics analysis showed that these two milk-clotting proteases were primarily involved in hydrolase activity and catabolic process, and exhibited hydrophilicity. The secondary structure of MoFP 12 consisted of 43.65% helix, 13.23% strand, and 43.12% coil, and MoFP 13 consisted of 26.51% helix, 20.14% strand, and 53.35% coil. The proteases were stable in the pH range of 5.0 to 8.0 and showed their maximum MCA at 70℃. Additionally, by investigating the effect of proteases on caseins, κ-casein (CN) was observed to preferentially be hydrolyzed by the two proteases, followed by α-CN, and to a lesser extent β-CN. These findings revealed the main milk-clotting proteases in M. oleifera flowers and its milk-clotting properties, indicating its potential for application in the dairy and food sectors, especially in the cheese-making industry.

The Michael Porter Diamond approach. Level of international competitiveness of the Mennonite cheesemaking industry in Cuauhtémoc, Chihuahua, Mexico

Faced with globalization and its impacts on the promotion of trade, local consumers gained access to international brands and entrepreneurs were able to offer their goods and services in other climes, translating into an economic benefit. Unfortunately, many artisanal businesses, such as the cheesemakers of Cuauhtémoc in the state of Chihuahua, Mexico, do not enjoy these same effects, as they fail to implement technical processes or marketing strategies and their commercial vulnerability increases as a result. This study employed Michael Porter’s diamond model to assess this industry in terms of its competitiveness. The research is mixed: 26 cheesemakers were sampled, three experts in the field were interviewed, and the data was analyzed using SPSS software. It is concluded that the cheese cluster presents weaknesses in the relationships with suppliers and in the marketing networks, while a notable strength is the high product quality. Given these findings, an intercultural negotiation strategy between the various actors is proposed in order to maximize the potential of this distinctive regional product.

The effect of probiotic crops and lipolytic enzymes on the properties of dairy products in the cheese biotechnology under development

This article aims to evaluate the influence of probiotic microorganisms and pregastric lipase on organoleptic and biochemical characteristics of soft cheese made from a mixture of milk and buttermilk. The study was designed to determine how the temperature and exposure at this temperature affect the growth and development of lactose and bifidobacteria, as well as their quantity in the finished product. In order to increase the biological and nutritional value of the developed soft cheese, protein-carbohydrate raw materials rich in vitamins A, B12, D, E, phosphate and minerals were introduced into the production mixture. The addition of buttermilk increased the biological value of the product and improved its consistency. The taste and consistency of cheese was improved by a pregastric lipase preparation, widely used in the cheesemaking industry for production of various cheeses with high and low temperatures of the second heating. As a result of directed lipolysis, the finished product accumulates free fatty acids and diacylglycerols, acting as plasticizers and affecting the texture and organoleptic characteristics of the cheese. The results show that combining buttermilk and milk in an optimal ratio and addition of lipase produce a product with the best physicochemical parameters and a maximum evaluation of organoleptic characteristics. In the presence of a probiotic starter culture (provided there is a ready-made substrate), an active synthesis of enzymes necessary for the complete hydrolysis of milk fat begins. This all creates a functional product.

Design of systems for integrated processing of dairy raw materials in the cheese industry

For the functioning of integrated systems for processing dairy raw materials in the cheesemaking industry, it is proposed to consider the basic concepts of synthesis of production systems. In order to implement the concept of waste minimization, it is proposed to separate the industrial wastewater into flows based on the concentration and values of the main parameters, as well as to protect the cheese whey from entering the water treatment facilities and direct it for disposal. The possibilities of implementing the concepts of deep raw materials processing into a target product have been analyzed, as well as the full utilization of raw and auxiliary materials. To this end, an experimental study was performed on the extraction of protein clots and adjusting the buffer capacity of infant dairy products using cheese whey. The study results indicate the insufficient effect of extracting the protein clot from whey (5–50 %) by combining the thermal and chemical processes. It was established that the redox conditions of the medium, in terms of the Eh indicator, can significantly affect the results, in close connection with the pH parameter and the estimated value of rH2. It was found that the optimal conditions for the functioning of lactic acid microflora in the production of soft cheeses can be ensured by adjusting the Eh indicator through the introduction of whey of pH=4.4–4.6 units, Eh≤–0.1 V. Whey is introduced at the stage of dairy raw material fermentation, which creates optimal conditions for the formation of a clot until reaching rH2 in the range from −5 to –7, and increases the product output by 1.5–7 %. The results of the experimental study indicate the high potential of using whey desalinated by ion exchange in order to reduce the buffer capacity in terms of acidity and adjust the redox conditions for infant milk mixtures until achieving rH2=15.5–15.9. The research reported in this paper could be the basis for the further development of systems for the integrated processing of dairy raw materials in the cheesemaking industry

Proteomics analysis of the bio-functions of Dregea sinensis stems provides insights regarding milk-clotting enzyme

Dregea sinensis (D. sinensis) stems have traditionally been used as milk coagulant in Dali of Yunnan Province, China. In this study, proteomics was used to investigate the bio-functions of D. sinensis stem proteins, leading to the purification and identification of the milk-clotting enzyme. A total of 205 proteins mainly involved in the catalytic and metabolic processes were identified, of which 28 proteins exhibited hydrolase activity. Among the 28 proteins, we focused on two enzymes (M9QMC9 and B7VF65). Based on proteomics, a cysteine protease (M9QMC9) with a molecular weight of 25.8 kDa and milk-clotting activity was purified from D. sinensis stems using double ammonium sulfate precipitation and was confirmed using liquid chromatography-mass spectrometry (LC-MS/MS). The milk-clotting temperature using the purified enzyme was around 80 °C (specific activity at 314.38 U/mg), and it was found to be stable in the pH range of 6–9 in NaCl concentration of <0.8 mol/L. These findings indicated that the enzyme isolated from D. sinensis stems has potential in the dairy and food sectors, especially in the cheese-making industry.

Renewable energy from the solid-state anaerobic digestion of grape marc and cheese whey at high treatment capacity

Globally, wine production annually generates some 11 million metric tonnes of grape marc (GM) while the cheese-making industry releases over 200 million m3 y−1 of effluent. Where value-creation mechanisms are absent, such wastes may be channelled to landfills. The study aimed to evaluate the bioenergy potential of the combined treatment of such wastes. Digestion of feedstock at a ratio 3/1 GM/CW (w/w) was conducted in unstirred conditions at 45 °C, following optimisation through the Taguchi Method. Cumulative biogas and methane yields were 0.601 m3 gas kg−1 VS and 0.363 m3 CH4 kg−1 VS, respectively. Firmicutes and Bacteroides mediated hydrolysis and acidogenesis, thus providing metabolites to Methanosarcina. Co-digestion can potentially generate 1330 GW h and 482,000 Mt CO2-equivalents avoidance. Wine and dairy industries jointly present a case for value-creation through a circular economy, thereby reducing the dependency on non-renewables, renewing commitment to the Paris Agreement.

Production of Maral (Cervus elaphus sibiricus Severtzov) Recombinant Chymosin in the Prokaryotic Expression System and the Study of the Aggregate of Its Biochemical Properties Relevant for the Cheese-Making Industry

The paper reports on the production of the maral recombinant chymosin in the Escherichia coli expression system (SHaffle express strain) and the study of its biochemical properties relevant for the cheese-making industry. The highest maral recombinant prochymosin content in inclusion bodies was observed when producer cells were cultured at 25°C for 6 h after the introduction of an inducer, 10 mM isopropyl-β-D-1-thiogalactopyranoside. The biochemical properties of the obtained enzyme were compared with those of bovine and dromedarian recombinant chymosins. It is shown that total proteolytic activity of the maral recombinant chymosin was comparable with that of the bovine enzyme and that it exceeded the activity of the dromedarian enzyme by about 3.8 times. The thermal stability of the recombinant chymosin from maral was found to be 5–10°C higher than that of the chymosins from the cow and dromedary. The patterns of dependence of milk-clotting activity on the pH level and calcium chloride concentration in cow’s milk on the enzyme from maral met the requirements set by the cheese industry. Its high proteolytic activity and thermal stability limits the scope of application of maral recombinant chymosin to the production of cheeses with short ripening and short storage times.

Life-Cycle Assessment of Dairy Products—Case Study of Regional Cheese Produced in Portugal

Nowadays, there is a growing promotion to label products ecologically in European markets. Knowing that daily products have relevant environmental impact associated with their production, it is of utmost importance to analyse all the related production processes for a better understanding of each process impact. The present study analysed the potential environmental impacts of a Portuguese regional product, the Beira Baixa cheese, coming from the largest national sheep milk region. So, a life cycle assessment (LCA) methodology is used from -cradle-to -gate, including the supplying of the animal feedstock. Impact calculations are performed using the ReCiPe midpoint 2008 method, allowing an analysis of the environmental impacts contributing to climate change, terrestrial acidification, freshwater and marine eutrophication of all productive processes. The results have shown that the greatest impacts occur within the milk production process for all four selected impact categories. This happens mainly due to the fodder cultivation process, also necessary to produce animal feed, which contain processes of fertilization and land preparation. The enteric fermentation and manure management processes have also shown relevant contributions. The impact assessment also showed that the cheesemaking industry has practically insignificant impacts. Nonetheless, the cheesemaking industry can promote their business with these results, by advertising and marketing their product as environmentally friendly, with production processes causing reduced impacts, and therefore also their products.

Production of Antioxidant and ACEI Peptides from Cheese Whey Discarded from Mexican White Cheese Production.

Cheese whey, a byproduct of the cheese-making industry, is discarded in many countries in the environment, causing pollution. This byproduct contains high-quality proteins containing encrypted biologically active peptides. The objective of this work was to evaluate the suitability of using this waste to produce bioactive peptides by enzymatic hydrolysis with a digestive enzyme. Cheese whey from white cheese (Panela cheese) was concentrated to increase total protein and hydrolyzed with trypsin. A central composite design was used to find the best conditions of pH and temperature, giving the higher antioxidant capacity and Δ Angiotensin-converting enzyme inhibition (Δ ACEI) activity. Higher biological activities were found when hydrolysis was performed at 52 °C and a pH of 8.2. The maximum value for the 2,2- diphenyl-1-picrylhydrazyl (DPPH)-scavenging activity was 26%, while the higher Δ ACE inhibition was 0.89. Significant correlations were found between these biological activities and the peptides separated by HPLC. The hydrophilic fraction (HI) showed highly significant correlations with the antioxidant capacity (r = 0.770) and with Δ ACE inhibition (r = 0.706). Antioxidant capacity showed a significant positive correlation with 34 peaks and Δ ACE inhibition with 33 peaks. The cheese whey was successfully used as raw material to produce peptides showing antioxidant capacity and ACEI activity.

The use of acid whey for the production of yogurt-type fermented beverages

Acid whey is a by-product of cheese-making industry, which, in comparison to rennet whey, has less favourable processing properties and thus it is more difficult to utilize. The aim of the study was to evaluate the quality of yogurt-type fermented beverages based on acid whey. In the beverages production yogurt bacteria cultures Streptococcus thermophilus and Lactobacillus delbruecki ssp. bulgaricus (YO-MIX, Danisco, Denmark) were used. The production process included combining of pasteurized acid whey with UHT milk, unsweetened condensed milk or skimmed milk powder. Milk was incorporated to beverages in order to enrich casein content and obtain product with quality characteristics similar to fermented milk drinks. Moreover, the beverages were supplemented with oligofructose and whey protein concentrate WPC 35. The products were stored under refrigerated conditions (5±1°C) for 21 days. During the storage, an assessment of physicochemical properties and sensory characteristics was carried out. In addition, the beverages were evaluated in consumer preference test. The study showed, that by combining of acid whey with milk it is possible to obtain a products similar to yogurt, although their characteristics were influenced by the composition and storage time. During storage period, the acidity increased and acetaldehyde content decreased. Moreover the deterioration of sensory properties was observed. Consumer preference test indicated, that the best sensory properties had beverages from whey and condensed milk.

Potential application of essential oils as antimicrobial preservatives in cheese

Increasing demand of consumers to use food products without preservatives or natural preservatives as possible has compelled the food industries for utilization of preservatives with herbal and microbial origins instead of artificial preservatives in their production. Essential oils are volatile, natural plant-derived substances that are used in medicine, food flavoring and food preservation. These diverse compounds represent considerable potential antioxidant, antibacterial and antifungal activities via various mechanisms. This review represents an overview on the impact of essential oils and their constituents as natural antimicrobials versus common pathogenic and spoilage microorganisms in cheese along with the related mechanisms of actions. Natural preservatives have proven popularity such that interest continues in substituting artificial additives with natural. Therefore, production of safe food without or with low amounts of synthetic preservatives is one of the most important challenges in the food industry. This review, introduces the potential application of essential oils as natural antimicrobial agents for reduction of common spoilage and pathogenic bacteria as well as molds and yeasts in cheese-making industry.

Estimation of coagulation time in cheese manufacture using an ultrasonic pulse-echo technique

The essential parameter in the cheese-making industry is the coagulation time because it marks the end point of the enzymatic phase and the start point of the aggregation. Furthermore, it is used to evaluate the cutting time that characterizes the time at which curd is cut. This paper proposes a non-destructive ultrasonic pulse-echo to monitor in real-time the acoustic impedance of milk during cheese manufacturing in order to predict the coagulation time. The evolution of the acoustic impedance is going through two phases the enzymatic phase and the aggregation phase. The transition point between these two phases defines the milk coagulation time. Three rennet concentrations and three temperatures were considered in our experiments to study the effect of these factors on coagulating milk. The experimental results prove that our proposed method determines the coagulation time with efficiency, and it is more simple compared with our previous work in which the phase velocity was used to determine the milk coagulation time.