Rheological, textural and melting properties of commercial samples of some of the different types of pasteurized processed cheese

The detailed rheological and textural properties of commercially available samples of the three major categories of pasteurized processed cheese in the USA, that is, pasteurized process American cheese (PPA), pasteurized process cheese product (PPP) and pasteurized process cheese food (PPF), were analysed. All samples had similar pH values, ranging from 5.65 to 5.87, but most were ∼5.7. Even within each of the categories considerable differences were observed in textural and melting behaviour. The samples with the lowest melt and the lowest loss tangent parameter from the rheological tests were two PPF and one PPA samples. These two PPF samples also had the highest hardness and adhesiveness force. Significant correlations were observed between several textural, rheological and melting properties.     

The effect of cheese maturity on selected properties of processed cheese without traditional emulsifying agents

The aim of this work was to compare selected properties (hardness, cohesiveness, adhesiveness, characteristics of fat globules, pH, meltability and sensory characteristics – homogeneity, rigidity and flavour) of processed cheeses (dry matter content 40 g/100 g; fat in dry matter content 50 g/100 g) made with traditional emulsifying salts (sodium salts of phosphates) and products in which the traditional emulsifying salts were replaced with 1 g/100 g κ-carrageenan. The development of the above-mentioned properties was studied in dependence on the maturity level of cheese (raw material; 1–16 weeks' maturity). The samples made without the use of traditional emulsifying salts were nearly five times as hard as the products with phosphates regardless of the maturity level of cheese. In both types of samples, hardness was decreasing and adhesiveness was rising with the increasing maturity level of cheese. Meltability of the samples without traditional emulsifying salts was very low and remained practically unchanged with the increasing maturity level of cheese. On the other hand, in the processed cheeses with phosphates, meltability was increasing with the rising maturity level of cheese.     

Texture,physicochemical and sensory properties of artisanal Adobera cheese from Los Altos de Jalisco,a genuine Mexican cheese

Physicochemical and sensory properties of Adobera, a genuine, understudied Mexican raw‐milk cheese, were explored by analysing commercial samples from different manufacturers and seasons. Composition‐wise, Adobera could be considered a fresh cheese with a high moisture content (42.5%), although its relatively low water activity (0.953) and pH (5.14) and high free amino acid content (0.46 mmol/g, dry basis) could indicate otherwise. Instrumental texture corresponded to that of a semifirm cheese, while its colour was whitish‐to‐ivory. Both texture and composition were significantly affected by sampling season and cheese composition, while some attributes of sensory acceptability significantly varied with brand.     

Effect of Penicillium roqueforti and incorporation of whey cheese on volatile profiles and sensory characteristics of mould‐ripened Civil cheese

In this study, four different types of mould‐ripened Civil cheese were manufactured. A defined (nontoxigenic) strain of a Penicillium roqueforti (SC 509) was used as secondary starter for the manufacture of mould‐ripened Civil cheese with and without addition of the whey cheese Lor; in parallel, secondary starter‐free counterparts were manufactured. A total of 83 compounds were identified. Ketones, alcohols and esters were the principal classes of volatile components. Principal component analysis of the headspace volatiles grouped cheeses by age and type. P. roqueforti inoculated cheese was clearly separated from the other cheeses at 180 days of ripening, and these cheeses were characterised with high levels of ketones (e.g., 2‐butanone, 2‐heptanone). Differences in the panel scores between the cheese samples were not significant during the first stage of ripening (up to 60 days); as ripening proceeded, these differences were become evident and P. roqueforti inoculated cheeses received higher scores than others. Addition of Lor in the manufacture of mould‐ripened Civil cheese caused lower points by the sensory panel, and the cheese inoculated with P. roqueforti and Lor‐free was the best type of mould‐ripened Civil cheese. The results showed that the use of P. roqueforti in the manufacture of mould‐ripened Civil cheese has significant impact on the volatile profiles and sensory attributes.     

Effect of the type of fat on rheology,functional properties and sensory acceptance of spreadable cheese analogue

The objective of this work was to evaluate the effect of different types of fat (butter oil, partially hydrogenated soybean fat and soybean oil) on the functionality, rheology and sensory acceptance of spreadable cheese analogues. Analogues made with partially hydrogenated soybean fat or soybean oil in substitution to butter oil presented lower fat globule size. As a consequence, these analogues showed lower melting, lower spreadability, higher hardness and higher values for the elastic and viscous moduli than cheese made with butter oil. Despite not managing to imitate the flavour of the traditional cheese, the analogue made with partially hydrogenated soybean fat showed good sensory acceptance.     

Prediction of processed cheese instrumental texture and meltability by mid-infrared spectroscopy coupled with chemometric tools

The objective of this study was to determine the potential of mid-infrared spectroscopy coupled with multidimensional statistical analysis for the prediction of processed cheese instrumental texture and meltability attributes. Processed cheeses (n = 32) of varying composition were manufactured in a pilot plant. Following two and four weeks storage at 4 °C samples were analysed using texture profile analysis, two meltability tests (computer vision, Olson and Price) and mid-infrared spectroscopy (4000–640 cm⁻¹). Partial least squares regression was used to develop predictive models for all measured attributes. Five attributes were successfully modelled with varying degrees of accuracy. The computer vision meltability model allowed for discrimination between high and low melt values (R² = 0.64). The hardness and springiness models gave approximate quantitative results (R² = 0.77) and the cohesiveness (R² = 0.81) and Olson and Price meltability (R² = 0.88) models gave good prediction results.     

Texture concepts for consumers: a better understanding of crispy–crunchy sensory perception

Differences in the definitions and terms used by consumers to describe their sensory sensations of crispness/crunchiness were studied, highlighting the relevance of using well-defined terms in consumer studies. A questionnaire was presented to consumers from two different Spanish-speaking countries (Spain and Uruguay, n = 200). The answers showed that the terms crispy and crunchy had different meanings or evoked different perceptions depending on the country. The crispy/crunchy food items most frequently mentioned by consumers were dry-crisp, processed products; vegetables or other wet-crisp products were not often mentioned by the consumers interviewed. The main difference between the two countries was that 38% of Spanish consumers did not know the Spanish term for “crunchy” and 17% thought that “crispy” and “crunchy” had the same meaning. The results contribute to a greater knowledge of the terminology used by the consumers to describe oral sensations related to crispness and crunchiness.     

Characterisation of aroma‐active compounds,chemical and sensory properties of acid‐coagulated cheese: Circassian cheese

The objectives of this study were to determine basic composition, aroma and sensory characteristics of Circassian cheese. Seven Circassian cheeses were provided by local producers. Aroma compounds were extracted by using solid‐phase microextraction procedure and determined by gas chromatography‐olfactometry system. Water‐soluble, trichloroacetic acid‐soluble and phosphotungstic acid‐soluble nitrogen fractions ranged between 2.30–29.35%, 2.48–9.96% and 3.33–6.26%, respectively. Diacetyl, butyric acid, 2‐acetyl‐1‐pyrroline, 1‐octen‐3‐one and methional were identified at high intensities in cheeses. In addition, ‘cooked’, ‘whey’, ‘creamy’ and ‘fermented’ were defined as characteristic flavour terms for Circassian cheeses.     

Pathway-based genome-wide association analysis of milk coagulation properties,curd firmness,cheese yield,and curd nutrient recovery in dairy cattle

It is becoming common to complement genome-wide association studies (GWAS) with gene-set enrichment analysis to deepen the understanding of the biological pathways affecting quantitative traits. Our objective was to conduct a gene ontology and pathway-based analysis to identify possible biological mechanisms involved in the regulation of bovine milk technological traits: coagulation properties, curd firmness modeling, individual cheese yield (CY), and milk nutrient recovery into the curd (REC) or whey loss traits. Results from 2 previous GWAS studies using 1,011 cows genotyped for 50k single nucleotide polymorphisms were used. Overall, the phenotypes analyzed consisted of 3 traditional milk coagulation property measures [RCT: rennet coagulation time defined as the time (min) from addition of enzyme to the beginning of coagulation; k₂₀: the interval (min) from RCT to the time at which a curd firmness of 20 mm is attained; a₃₀: a measure of the extent of curd firmness (mm) 30 min after coagulant addition], 6 curd firmness modeling traits [RCT_eq: RCT estimated through the CF equation (min); CF_P: potential asymptotic curd firmness (mm); k_CF: curd-firming rate constant (% × min^?1); k_SR: syneresis rate constant (% × min^?1); CF_max: maximum curd firmness (mm); and t_max: time to CF_max (min)], 3 individual CY-related traits expressing the weight of fresh curd (%CY_CURD), curd solids (%CY_SOLIDS), and curd moisture (%CY_WATER) as a percentage of weight of milk processed and 4 milk nutrient and energy recoveries in the curd (REC_FAT, REC_PROTEIN, REC_SOLIDS, and REC_ENERGY calculated as the % ratio between the nutrient in curd and the corresponding nutrient in processed milk), milk pH, and protein percentage. Each trait was analyzed separately. In total, 13,269 annotated genes were used in the analysis. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway databases were queried for enrichment analyses. Overall, 21 Gene Ontology and 17 Kyoto Encyclopedia of Genes and Genomes categories were significantly associated (false discovery rate at 5%) with 7 traits (RCT, RCT_eq, k_CF, %CY_SOLIDS, REC_FAT, REC_SOLIDS, and REC_ENERGY), with some being in common between traits. The significantly enriched categories included calcium signaling pathway, salivary secretion, metabolic pathways, carbohydrate digestion and absorption, the tight junction and the phosphatidylinositol pathways, as well as pathways related to the bovine mammary gland health status, and contained a total of 150 genes spanning all chromosomes but 9, 20, and 27. This study provided new insights into the regulation of bovine milk coagulation and cheese ability that were not captured by the GWAS.     

The effects of probiotic cultures on the organic acid content,texture profile and sensory attributes of Tulum cheese

The aim of this study was to evaluate the effects of Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis on the organic acid, texture profile and sensory attributes of Tulum cheese. The acidity of sample increased throughout the storage. Storage time influenced the organic acid content of samples (P < 0.0001). Lightness decreased while redness increased (P < 0.05). Cohesiveness decreased during storage, whereas the values of all other Texture Profile Analyses (TPA) parameters increased. The samples produced with L. acidophilus had the highest texture and acceptability ratings, whereas samples produced with B. animalis subsp. lactis had the highest flavour score.     

Textural and microstructural properties of Kradi cheese (an indigenous cheese of Jammu and Kashmir,India)

The texture and microstructure of Kradi cheese, an indigenous fresh unripened cheese of Jammu and Kashmir, India, were studied. There were significant differences (P < 0.05) for hardness, adhesiveness, springiness, cohesiveness, chewiness and resilience between samples from four different market areas. The optimised products made in the laboratory from cultures NCDC‐167 and NCDC‐144 showed significant differences (P < 0.05) in the textural and mechanical properties of tensile strength. The microstructure of the market samples was distinguished by the greater size of the voids present in three‐dimensional casein network. The optimised laboratory product had a more compact and fibrous structure compared to the market samples, which was attributed to its higher protein content.     

Effects of Penicillium roqueforti and whey cheese on gross composition,microbiology and proteolysis of mould‐ripened Civil cheese during ripening

Four different types of mould‐ripened Civil cheese were manufactured. A defined (nontoxigenic) strain of a Penicillium roqueforti (SC 509) was used as the secondary starter with and without addition of the whey cheese (Lor); in parallel, secondary starter‐free counterparts were manufactured. Chemical composition, microbiology and proteolysis were studied during the ripening. The incorporation of whey cheese in the manufacture of mould‐ripened Civil cheese altered the gross composition and adversely affected proteolysis in the cheeses. The inoculated P. roqueforti moulds appeared to grow slowly on those cheeses, and little proteolysis was evident in all cheese treatments during the first 90 days of ripening. However, sharp increases in the soluble nitrogen fractions were observed in all cheeses after 90 days. Microbiological analysis showed that the microbial counts in the cheeses were at high levels at the beginning of ripening, while their counts decreased approximately 1–2 log cfu/g towards the end of ripening.     

Assessment of the quality of cottage cheese produced from standard and protein-fortified skim milk

The effects of milk protein fortification on the texture and microstructure of cottage cheese curd were evaluated. Protein powder (92.6% protein) was added to the skim milk at a level of 0.4% (w/w) to produce curds. Control curds with no protein powder addition were also produced. These curds were analysed for differences in yield, total solids, curd size, texture and structure. It was found that the addition of protein powder contributed to a significant yield increase, which can be attributed to increased water retention, with better curd size distribution. Control curds were firmer than the fortified curds and the structure showed less open-pore structure as revealed by electron microscopy. However, the addition of dressing masked the textural differences, and a sensory panel was unable to distinguish between cheeses produced from fortified milk and controls.     

Evaluation of iron‐fortified Feta cheese for physicochemical and sensory properties

Standardised cow's milk (fat 3 g/100 g) was used to manufacture Feta cheese fortified with 40, 60 and 80 mg of iron/kg cheese using ferrous sulphate (FeSO₄), ferric chloride (FeCl₃), ferric pyrophosphate (Fe₄ (P₂O₇)₃) and microencapsulated ferrous sulphate. Chemical composition and sensory characteristics of fortified cheeses were determined after 60 days of ripening, during which the iron content and thiobarbituric acid (TBA) values were measured. The metallic taste, colour, flavour, overall score and TBA values were statistically (P < 0.05) affected by the source and concentration of iron. The best quality was found in cheeses fortified with 40 mg/kg of microencapsulated ferrous sulphate.     

Reduction in sodium content of fresh,semihard Tzfat cheese using salt replacer mixtures: taste,texture and shelf life evaluation

Tzfat cheese is a semihard, fresh cheese commonly produced in Israel, with an average sodium content of 1000 mg/100 g cheese. Reduction in sodium levels by 30% and 50% (w/w) with and without salt replacer mixtures was assessed in terms of cheese physicochemical, microbiological and sensory properties. Cheese, containing 30% KCl and 70% NaCl had the closest taste profile to the control cheese, according to electronic tongue analysis. All cheeses underwent a similar increase in extent of proteolysis and microbial growth during shelf life. This study demonstrates the possibility of reducing the sodium content in fresh, semihard cheeses like Tzfat cheese by more than 30% using salt replacer mixtures, without significantly affecting quality.     

Changes in the composition and sensory properties of Croatian cheese in a lamb skin sack (Sir iz mišine) during ripening

Croatian traditional cheese, which ripens in a lamb skin sack, was studied to determine compositional, biochemical and sensory changes over 60 days of ripening. The ripening time had a significant effect on the chemical, biochemical and sensory parameters, particularly on the medium‐ and long‐chain free fatty acids (P < 0.05) and total FFAs (P < 0.001). At the end of ripening palmitic, oleic and stearic acids were the predominant FFAs. Cheese ripened for more than 45 days was less acceptable to consumers as a consequence of extensive proteolysis and lipolysis. Therefore, ripening for more than 45 days, which is commonly practised by cheesemakers, is not recommended.     

Changes of physicochemical, microbiological, and textural properties during ripening of Italian low-acid sausages. Proteolysis, sensory and volatile profiles

In this study low-acid sausages were studied to characterize their physicochemical, microbiological, and textural properties during ripening. The final a(w) was 0.87-0.88, whereas pH values stayed around their initial values during processing. Lactic acid bacteria increased very slowly in number and a small increase of Micrococcaceae was also noticed. Low-acid sausages showed low hardness and cohesiveness, and were easily distinguishable by sensory analysis from other industrial and artisan sausages. Under the conditions of the study, observed volatile compounds were mainly from spices and wine. The respective contribution of muscle and indigenous bacterial enzymes to proteolysis was determined by comparing changes in low-acid sausages to those containing an antibiotic-antimycotic mixture or sugar. A large part of the degradation of myofibrillar proteins appeared due to endogenous enzymes, although bacterial proteinases contributed to the degradation of these proteins. The role of microorganisms in proteolysis was more evident in the degradation of sarcoplasmic proteins.     

The effect of concentration of chymosin on the yield and sensory properties of camel cheese and on its microbiological quality

The transformation of camel milk into soft cheese by using chymosin and yoghurt starter culture (Streptococcus thermophilus and Lactobacillus bulgaricus) was investigated. The cheese yield and sensory properties were related to the concentration of chymosin. A yield of 16.74 g/100 mL of milk was obtained with a chymosin concentration of 1.7 mL/L of milk. The cheeses obtained with concentrations ranging between 1.0 mL and 2.9 mL of chymosin/L of milk scored highly regarding their sensory properties and had an acceptable microbiological quality. This study demonstrated that cheesemaking from camel milk can be made successfully providing that the appropriate chymosin concentration is used; and that 1.7 mL of chymosin/L of milk was optimal.     

Use of low concentration factor ultrafiltration retentates in reduced-fat Minas Frescal cheese manufacture: effect on yield and sensory properties

The yield and sensory properties of reduced-fat Minas Frescal cheese made from low concentration factor (CF) retentates were studied. Three different CFs were tested (1.2, 1.5 and 1.8). The chemical compositions of the milk, retentate, whey and cheese were determined, as well as the cheese yield. The cheese moisture content decreased with increasing CF. The cheese yield was significantly dependent on the CF in the same direction as the moisture content. Despite compositional differences among the samples, only the cheese made with a CF of 1.8 presented low sensorial acceptance. CF 1.2 was found to be the optimum value for reduced-fat Minas Frescal cheese manufacture in the CF range studied.