Impact of physiological state of starter culture on ripening and flavour development of Swiss–Dutch‐type cheese

The changes in the physiological state and metabolism of starter culture in 15kg Swiss–Dutch‐type cheese blocks during two‐stage ripening were studied. The analyses were performed on samples from three layers of cheese between the rind and the core. Cell membrane integrity, intracellular esterase activity and bacteria culturability were chosen as physiological state indicators. Cheese flavour development was determined by static headspace gas chromatography. During warm room ripening, the number of cells with intact cell membranes and displaying intracellular esterase activity increased. Lactic acid bacteria underwent resuscitation and regained their culturability. A lack of homogeneity within the cheese was noticed in relation to bacterial activity and the volatiles concentration.     

Fatty acid profiling of bovine milk and cheese from six European areas by GC‐FID and GC‐MS

The fatty acid (FA) composition of milk from six European areas, as well as the alteration in the FA profile during cheese production, was studied using both a targeted GC‐FID and an untargeted GC‐MS approach. By applying principal component, partial least square discriminant and chemical similarity enrichment analysis, a discrimination of the geographical areas could be achieved highlighting important FA classes such as odd‐ and branched‐chain FAs for the differentiation. The FA profile remained constant during cheese production, and aroma compounds have been identified as biomarkers for the ripening methods used, namely foil and smear ripening.     

Chemical and biochemical study of industrially produced San Simón da Costa smoked semi-hard cow's milk cheeses: Effects of storage under vacuum and different modified atmospheres

Two batches of smoked, semi-hard (ripened for 45 d) San Simón da Costa cow's milk cheeses with Protected Designation of Origin were used to investigate the chemical, biochemical, and sensorial parameters that may be affected by modified-atmosphere packaging. Cheeses were packaged for 45 d as follows: vacuum packaging, packaging in 100% N₂, packaging in a gas mixture of 20% CO₂/80% N₂, and packaging in a gas mixture of 50% CO₂/50% N₂. The San Simón da Costa cheeses were characterized by high contents of lactic, oxalic, and citric organic acids. The main free amino acids found were isoleucine, phenylalanine, serine, valine, lysine, and glutamic acid, and the most abundant volatile compounds included ethanol, diacetyl, 2-butanol, isopropyl alcohol, furfural, acetaldehyde, 2-butanone, acetone, and 2-methylfuran. Modified atmospheres appeared to alter the ripening processes by affecting lipolysis, as indicated by the lower concentrations of butyric and propionic acids compared with control cheeses. In addition, modified-atmosphere packaging altered the proteolysis processes, yielding higher amounts of branched-chain alcohols. The results revealed that storage under modified atmosphere contributes to the accumulation of several compounds probably derived from smoke, including aldehydes such as 2-furancarboxaldehyde (furfural), alcohols such as 2-methoxyphenol (guaiacol), ketones such as 2-cyclopenten-1-one, and esters such as methyl furancarboxylate, which were negatively correlated with flavor. Vacuum packaging was the most useful technique in terms of preserving the sensory quality of San Simón da Costa Protected Designation of Origin cheeses. Considering the current demands for packaged portions of food at the distribution and retail levels and the potential health risks associated with some smoke-derived compounds usually present in some smoked foods, the results obtained in this study may be of special interest to the cheese industry.     

The compositional properties,proteolytic–lipolytic maturation parameters and volatile compositions of commercial enzyme‐modified cheeses with different cheese flavours

Eight different commercial enzyme‐modified cheeses (EMCs) were analysed, and the distinctive/common features of the products and production methods were investigated. Results showed that the total free fatty acid contents of EMC samples were 10 to 100 times higher than the values reported for the related cheese varieties. A total of 37 volatile compounds were identified, and acids were found as the most dominant group in all EMC samples. While furan compounds and 2‐acetylpyrrole were most intensively detected in the goat cheese EMC, methyl ketones were found in the highest amounts in Blue cheese EMC.     

Microbiological,biochemical and compositional changes during ripening of São Jorge – a raw milk cheese from the Azores (Portugal)

The microbial, compositional and biochemical profiles of São Jorge cheese (PDO) obtained from three distinct cheese plants, throughout the ripening period were determined. Fully ripened cheeses (i.e. by 130 days) contained a total of 3.1 × 10⁷ CFU g⁻¹ mesophilic bacteria, and a decrease in moisture content, concomitantly with an increase in salt content, was observed throughout the same time frame. The pH decreased until 30 days of ripening; thereafter, a slight increase was reported, up to 5.6 by the end of ripening. Urea-PAGE results showed extensive primary proteolysis, of both β-casein and α_s1-casein − degraded at essentially similar rates; plasmin and chymosin accordingly appear to be active in the cheese curd. RP-HPLC profiles of water-soluble fractions showed minor differences between 1 and 130 day old cheeses, whereas equivalent profiles of 7% (v/v) ethanol-soluble fractions contained several peaks, indicative of a heterogeneous mixture of products of proteolysis, that evolved with time.     

The effect of two types of mould inoculants on the microbiological composition,physicochemical properties and protein hydrolysis in two Gorgonzola‐type cheese varieties during ripening

The aim of this paper was to investigate the role of two types of Penicillium roqueforti moulds (type esportazione and dolce) in the ripening of two Gorgonzola‐type cheese varieties. Cheeses were analysed after 4, 14, 30 and 60 days of ripening. Microbiological analysis showed high numbers of total bacterial count, yeasts and moulds in both 60‐day‐old cheese varieties. The concentration of water‐soluble N, nonprotein N and 5% phosphotungstic acid‐soluble N increased significantly during ripening. Patterns of proteolysis by urea‐polyacrylamide gel electrophoresis showed that rind‐to‐core gradients and age‐related changes in moisture and salt content influenced mould and other enzyme activities, which are reflected in various rates of protein degradation. The hydrolysis of αs₁‐ and β‐caseins was more extensive in the core than under the rind of both cheese varieties.     

Ripening of traditional Örgü cheese manufactured with raw or pasteurized milk: Composition and biochemical properties

The changes in composition and some biochemical properties of Örgü cheeses made from raw (RMC) and pasteurized (PMC) cow milk were investigated during a 90-day ripening period. The average contents of total solids (TS), protein, water soluble nitrogen (WSN), trichloro-acetic acid soluble nitrogen (TCA-SN) and acid degree value (ADV) were lower, while salt and salt in TS were found to be statistically higher in PMC than RMC (P < 0.05). In addition, in both RMC and PMC, the TS and protein contents were decreased as compared to an increase in salt, salt in TS, WSN and TCA-SN contents, and ADV, during ripening (P < 0.05). The evaluation of WSN, TCA-SN and ADV shows that these two experimental Örgü cheese types undergo little proteolysis and lipolysis. On the other hand, acidity development was observed to be high in both before curdling and in cheese made from raw milk during ripening.     

Effects of curd heating with or without previous milk pasteurisation on the microbiological quality and safety of craft‐made ‘Pasta Filata’ Kashkaval cheese curds

An empirical ‘Pasta Filata’ process used for traditional Kashkaval cheese manufacture from raw ewes’ milk improved the hygiene of fresh curd. Coagulase‐positive (RPF+) staphylococci and coliforms declined by 2.4 and 4.5 log units, respectively, and Listeria contamination was minimised. Before Pasta Filata, RPF+ staphylococci exceeded the 5‐log threshold level specified in EC Regulation 1441/2007 in raw milk curds despite the prevalence of indigenous mesophilic lactic acid bacteria. Pasta Filata favoured enterococci in raw milk curds. Pasteurisation enhanced prevalence of Streptococcus thermophilus and Lactococcus lactis starters and microbial quality and safety of pasteurised milk curds before and particularly after Pasta Filata.     

A comparative study of submicron‐ and micron‐sized rice particles: enzymatic hydrolysis in vitro and food efficiency ratio in vivo

Hydrolysis and absorption properties of submicron‐ (below 1 μm) and micron‐sized (over 100 μm) powders of raw rice, heat‐gelatinized rice, fermented rice and wheat were investigated in vitro and in vivo. Nutrient content such as protein, carbohydrate or vitamin C in the samples was not different significantly between submicron‐ and micron‐sized powders, but it showed difference according to processed type of the powders. Submicron‐sized powders were hydrolyzed more easily than micron‐sized powders by α‐amylases such as industrial, human salivary and porcine pancreatic α‐amylase but not by α‐glucosidase in all the tested samples. Patterns of blood glucose change were investigated in rats. The highest glucose levels were obtained at 30 min after oral administration in both submicron‐and micron‐sized powders, but the levels were decreased drastically in groups administered submicron‐sized powders, while they were slow and gradual in groups administered micron‐sized powders. On the contrary, the body weight gained and food efficiency ratios showed a tendency to be decreased slightly in mice fed with submicron‐sized rice powders compared to those with micron‐sized rice powder.     

Physico‐chemical and sensory attributes in conjunction with multivariate analysis of two potato (Solanum tuberosum L.) cultivars after 90 days of storage: an exploratory authentication study

Two cultivars of potato (Spunta and Agria), were studied in terms of their physico‐chemical and sensory characteristics. These cultivars were cultivated in three geographical regions of Greece (Macedonia, North Greece; Thessaly, Central Greece; Peloponnese, South Greece) and were stored for 90 days after harvesting. The physico‐chemical characteristics of the tubers determined, were pH, total acidity, firmness, dry matter and content in Ν, in Κ, P, Cu, Mn, Zn and Fe. The sensory characteristics measured for raw tubers of potato after storage, were skin colour, skin brightness, internal colour, surface roughness, odour intensity, moistness, surface wrinkling and stains while the sensory characteristics measured for the boiled tubers of potato were odour intensity, moistness, special taste, sweet taste, aftertaste persistence, metal taste, pastiness, mastication, flavour intensity, elasticity and overall acceptability. The application of multivariate analysis (principal component analysis, cluster analysis and discriminant analysis), revealed a variety of relations between the various parameters and resulted in satisfactory grouping either per geographical region or per cultivar.     

Digestion of peanut allergens Ara h 1, Ara h 2, Ara h 3, and Ara h 6: A comparative in vitro study and partial characterization of digestion‐resistant peptides

Scope : There are differences in stability to pepsin between the major allergens in peanut; however, data are from different reports using different digestion models. This study provides a comprehensive comparison of the digestibility of the major peanut allergens. Methods and results : Peanut allergens Ara h 1, Ara h 2, Ara h 3 and Ara h 6 were incubated with pepsin to mimic the effect of gastric digestion. Samples were analyzed using SDS‐PAGE. To further investigate resistance to digestion, Ara h 2 was additionally subjected to digestion with trypsin and residual peptides were characterized. Ara h 1 and Ara h 3 were rapidly hydrolyzed by pepsin. On the contrary, Ara h 2 and Ara h 6 were resistant to pepsin digestion, even at very high concentrations of pepsin. In fact, limited proteolysis could only be demonstrated by SDS‐PAGE performed under reducing conditions, indicating an important role for the disulfide bridges in maintaining the quaternary structure of Ara h 2 and Ara h 6. Trypsin digestion of Ara h 2 similarly resulted in large residual peptides and these were identified. Conclusion : Ara h 2 and Ara h 6 are considerably more stable towards digestion than Ara h 1 and Ara h 3.