Effect of the type of emulsifying salt on microstructure and rheological properties of "requeijão cremoso" processed cheese spreads

Abstract: The role of different types of emulsifying salts—sodium citrate (TSC), sodium hexametaphosphate (SHMP), sodium tripolyphosphate (STPP) and tetrasodium pyrophosphate (TSPP)—on microstructure and rheology of “requeijão cremoso” processed cheese was determined. The cheeses manufactured with TSC, TSPP, and STPP behaved like concentrated solutions, while the cheese manufactured with SHMP exhibited weak gel behavior and the lowest values for the phase angle (G”/G’). This means that SHMP cheese had the protein network with the largest amount of molecular interactions, which can be explained by its highest degree of fat emulsification. Rotational viscometry indicated that all the spreadable cheeses behaved like pseudoplastic fluids. The cheeses made with SHMP and TSPP presented low values for the flow behavior index, meaning that viscosity was more dependent on shear rate. Regarding the consistency index, TSPP cheese showed the highest value, which could be attributed to the combined effect of its high pH and homogeneous fat particle size distribution.     

Effect of temperature on evolution of free amino acid and biogenic amine contents during storage of Azeitão cheese

A study on the evolution of free amino acids and biogenic amines in Azeitão cheese during 4 weeks at different temperatures of storage (4 and 25°C) was performed. Free amino acids and biogenic amines were determined by RP-HPLC with visible detection, following extraction from the cheese and derivatization with dabsyl chloride. The method presented a linear relation between peak area and concentration from 2–200 mg/l. The detection limit value was less than 1.5 mg/l. The average repeatability was less than 4%. The major free amino acids were proline, valine, isoleucine and leucine and the major amines were tyramine, cadaverine and histamine. Room temperature (25°C) promoted a significant increase of the contents of valine, leucine, tyramine and putrescine, expressed as g/kg of dry matter. These two free amino acids and two biogenic amines may serve as indicators of temperatures changes in ripened cheese.     

Influence of chemical and biochemical characteristics on the texture of Appenzeller® cheese

Texture properties are very important quality parameters of Appenzeller^® cheese. The Appenzeller^® Cheese Makers Association defines optimal texture quality as being characterised by a softness that lasts at least three months. During winter production, texture-related problems are sporadically encountered. In the present study, ten Appenzeller^® cheese loaves with optimal texture properties aged for 90 days and ten loaves with dry and firm texture of the same age were selected and characterised through a uniaxial compression test and with physicochemical and biochemical methods. All cheeses had been produced in the same week during winter (January) in different cheese factories and ripened for three months. The aim of the study was to determine the main factors responsible for classification into the two groups based on univariate and multivariate statistical analysis tools. The three main parameters influencing the force at 33% deformation in this study were calcium, water, and free amino acids.     

Antimicrobial resistance of Staphylococcus spp. isolated from organic and conventional Minas Frescal cheese producers in São Paulo,Brazil

The genus Staphylococcus is recognized worldwide as a cause of bacterial infections in humans and animals. Antibiotics used in dairy cattle combined with ineffective control can increase antimicrobial resistance. The objective of this study was to characterize 95 Staphylococcus strains isolated from organic and conventional Minas Frescal cheese production regarding antibiotic resistance (phenotype and genotype), presence of sanitizer-resistant genes and biofilm-formation genes, and SCCmec typing. Most strains (25.3%) showed higher resistance to penicillin, followed by oxacillin (21.1%) and clindamycin (11.6%). Among antibiotic resistance genes, the most prevalent were blaZ (25.3%), mecA (13.7%), lsaB (6.3%), msrA (4.2%), ant4 (3.2%), and tetM (2.1%); among sanitizer-resistance genes they were qacA/B (5.3%) and qacC (6.3%); and among biofilm, bap (4.2%), icaA (29.5%), icaD (41.1%). However, there was no statistically significant difference between organic and conventional dairy products, possibly due to the lack of synthetic antibiotic use on conventional farms during the sample collection period. Methicillin-resistant Staphylococcus aureus (MRSA) had their SCCmec identified as types I and IVc, and the methicillin-resistant coagulase-negative staphylococci had nontypeable SCCmec. These results suggest that there are antibiotic-resistant strains in both organic and conventional Minas Frescal cheese production in the state of São Paulo, Brazil. This supports the idea that improved quality control is needed from the milking stage up to the final product.     

Effects of Lactobacillus strains on the ripening and organoleptic characteristics of Arzúa-Ulloa cheese

Seven batches of Arzúa-Ulloa, a short-ripened soft cow's milk cheese produced in Galicia (NW Spain), were prepared from pasteurized milk. Two control batches of cheese (CB) were made with an acid-aromatic starter containing Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. lactis var. diacetylactis, isolated from raw-milk Arzúa-Ulloa cheeses. Five batches of cheese (LB) were made with the acid-aromatic starter plus one of five strains of mesophilic homofermentative Lactobacillus spp.: four of them isolated from raw-milk Arzúa-Ulloa cheese (characterized in previous works) and the remaining was a commercial Lactobacillus strain. Higher counts of mesophilic viable bacteria, lactic acid bacteria and citrate-fermenting bacteria were found on days 1 or 15 of ripening, while higher counts of lactobacilli were found on day 30 of ripening. On day 1 of ripening the highest diacetyl-acetoin content was noted in the CB, but after day 15 the diacetyl-acetoin content was similar or higher in three of the five LB. The mean degradation of beta-casein in CB was higher than in LB, while the degradation of alpha(s1)-casein was higher in LB. The mean contents of nitrogen-soluble fractions were slightly higher in the LB than in the CB. Volatile free fatty acid (VFFA) contents were, in general, greater in LB than in CB and maximum amounts were determined on day 15 of maturation. Sensorial analysis indicated a more acid taste was in LB, while bitter and astringent tastes were more intense in CB. A positive correlation was found between beta-casein degradation and bitter taste. Yogurt and butter aromas were more intense in CB and in two of the five LB. Firmness was lower in LB and a negative correlation was found between this parameter and alpha(s1)-casein degradation. Crumbliness showed a positive correlation with beta-casein degradation. The use of the Lactobacillus strains assessed in this study is recommended for Arzúa-Ulloa cheese manufacture, in order to enhance the desirable characteristics of this cheese variety, i.e., a soft texture due to alpha(s1)-casein proteolysis but without the bitter taste due to beta-casein degradation and a spicy and slightly rancid aroma and taste.     

Survey of aflatoxin M1 in cheese from the North-east region of São Paulo,Brazil

In the present study, 24 samples of Minas Frescal cheese and 24 samples of Minas Padrão cheese produced in the North-east region of the state of São Paulo, Brazil, were analysed for aflatoxin M₁ (AFM₁) by high-performance liquid chromatography (HPLC) between March and August 2008. AFM₁ was detected in 13 (27.1%) samples at concentrations ranging from 0.037 to 0.313?ng?g^?1. The mean concentrations of AFM₁ in positive samples of Minas Frescal and Minas Padrão cheese were 0.142?±?0.118 and 0.118?±?0.054?ng?g^?1, respectively. It is concluded that the incidence of AFM₁ in Minas cheese may contribute to an increase in the overall ingestion of aflatoxins in the diet, hence indicating the need for the adoption of a tolerance limit for AFM₁ in cheese in Brazil.     

Effect of calcium and sodium caseinates on physical characteristics of soy protein isolate–lipid films

The effect of addition of caseinates to soy protein isolated (SPI) based films containing lipids (33% of oleic acid or 85:15 oleic acid (OA)–beeswax blend (BW)) on water vapour permeability (WVP), mechanical and optical properties was evaluated. SPI–lipids was combined with caseinates (sodium or calcium) in different SPI:caseinate ratios with the aim of improving water vapour barrier, mechanical and optical properties of SPI films containing lipids. Caseinate incorporation to SPI based films provoked an increase of elastic modulus and tensile strength at break, mainly for calcium caseinate. Both caseinates contributed to increase the water vapour barrier properties of soy protein-based films. Caseinates also provoked an increase of transparency of SPI based films and colour softening. The most effective combination was 1:1 sodium caseinate:SPI ratio, when film contains 85:15 oleic acid:beeswax ratio.     

Incidence of Listeria monocytogenes in cheese manufacturing plants from the northeast region of São Paulo, Brazil

The incidence of Listeria monocytogenes in three cheese manufacturing plants from the northeastern region of S?o Paulo, Brazil, was evaluated from October 2008 to September 2009. L. monocytogenes was found in samples from two plants, at percentages of 13.3% (n = 128) and 9.6% (n = 114). Samples of raw and pasteurized milk, water, and Minas Frescal cheese were negative for L. monocytogenes, although the pathogen was isolated from the surface of Prato cheese and in brine from one of the plants evaluated. L. monocytogenes was also isolated from different sites of the facilities, mainly in non-food contact surfaces such as drains, floors, and platforms. Serotype 4b was the most predominant in the plants studied. The results of this study indicate the need for control strategies to prevent the dispersion of L. monocytogenes in the environment of cheese manufacturing plants.     

Evolution of the sensory characteristics of Parmigiano–Reggiano cheese to the present day

Parmigiano–Reggiano cheese is one of the most important Italian Protected Designation of Origin (PDO), and is exported worldwide. As a PDO the product should have distinctive sensory characteristics which come from the traditional method of production thus guaranteeing the consumer a sensory quality which lasts over time. This research gathers sensory information about the cheese starting from XV century, considering visual, olfactory, taste and texture characteristics.Until XIX century the characteristics of the cheese remained relatively stable. Important sensory changes happened in the XX century in relationship to the accelerated rate of modernization of the environment. The cheese still retained its granular texture being also tasty, a little sweet and rather fatty. The characteristics of Parmigiano–Reggiano mean that, as in XIV century Italy, it is still suitable today for grating over pasta.     

Effect of high-pressure treatment of ewe raw milk curd at 200 and 300 MPa on characteristics of Hispánico cheese

Hispánico cheese is a semihard variety made from a mixture of cow and ewe milks. Production of ewe milk declines in summer and autumn. To surmount the seasonal shortage of ewe milk and prevent the inactivation of milk enzymes by pasteurization, curd made in spring from ewe raw milk was pressurized at 200 and 300 MPa and stored frozen for 4 mo. Thawed ewe milk curds were added to fresh curd made from pasteurized cow milk for the manufacture of experimental Hispánico cheeses. Control cheese was made from a mixture of pasteurized cow and ewe milk in the same proportions as those used for experimental cheeses. Experimental cheeses exhibited lower dry matter content, higher aminopeptidase activity and total free amino acid concentration, and higher levels of acetic and propionic acids, aldehydes, alcohols, and esters compared with control cheese. In contrast, the concentration of total free fatty acids and ketones and the levels of textural parameters were significantly higher in control cheese. The use of ewe raw milk curd pressurized at 200 and 300 MPa, stored frozen and thawed for Hispánico cheese manufacture, was generally beneficial for cheese characteristics and increased cheese yield because of the lower dry matter content of experimental cheeses.     

Monitoring and identification of bacteria associated with safety concerns in the manufacture of São Jorge, a Portuguese traditional cheese from raw cow's milk

The aim of this study was to assess the hygienic quality of raw milk used in the manufacture of S?o Jorge, a Protected Denomination of Origin Portuguese semihard cheese, as well as to ascertain the sanitary conditions prevailing during its processing. Viable counts of Enterobacteriaceae and Micrococcaceae were accordingly obtained, pertaining to 21 independent batches (including samples of raw milk, curd, and cheeses after 1, 3, and 4 months of ripening), from 7 dairy farms. Standard plate counts (log CFU per milliliter or per gram) ranged from 6.1 to 8.6 in raw milk, whereas they ranged from 7.0 to 8.0 in 4-month-old cheeses. Viable counts of Enterobacteriaceae ranged between 5.9 and 7.0 in raw milk and between 0.0 and 1.3 in 4-month-old cheeses. Species identified within this family encompassed Klebsiella oxytoca, Klebsiella cloacae, Klebsiella pneumoniae, Enterobacter sakazakii, and Escherichia coli; Klebsiella ornithinolytica, Klebsiella terrigena, and Serratia odorifera were detected only in raw milk. No Salmonella whatsoever could be detected in any of the samples. Viable counts of Micrococcaceae ranged between 4.7 and 5.9 and between 1.3 and 3.3 in raw milk and 4-month-old cheeses, respectively. Species identified within this family encompassed Staphylococcus sciuri, Staphylococcus epidermidis, Staphylococcus saprophyticus (which was found mainly in ripened cheeses), and Staphylococcus aureus (which was not detected in 4-month-old cheeses). Accompanying physicochemical analyses included determination of moisture, salt, and pH. Statistical analyses revealed a negative correlation between salt content and viable numbers of Enterobacteriaceae in cheese, whereas in the case of Micrococcaceae, a more negative correlation was found between viable numbers and moisture content than between viable numbers and pH. The results of our study indicate, in general, poor milk handling conditions in all farms, given that the indicators total mesophile and Enterobacteriaceae counts were high, between 100- and 1,000-fold those enforced by international standards pertaining to the matrices in question. However, by the time of regular consumption (i.e., after 4 months of ripening), S?o Jorge cheeses exhibit low levels of contamination by Enterobacteriaceae and S. aureus, as well as absence of Salmonella.     

Heat–Moisture Treatment on Pinhão Starch Impacts the Properties of the Biodegradable Films

Using non-conventional starch can benefit the industry since it can present different properties. It also can lead to new properties upon physical modification, which improves its derivate film properties. Therefore, the aim of this work is to evaluate the heat–moisture treatment (HMT) on pinhão starch and its effectiveness in film properties. After isolation using water as a solvent, the pinhão starch is treated by HMT for 16 h at 110 °C. Native and HMTed starches are used to produce biodegradable films. Pinhão starch and starch films chemical and physical properties are properly characterized. The HMT causes some changes in short-range ordered structures, reduces the relative crystallinity, and shifts the pinhão starch from C-type to A-type. Also, HMT decreases the peak viscosity and the breakdown, and improves thermal stability. These starch changes upon HMT reduces water vapor permeability, increases tensile strength, and elongation at the break of pinhão starch films. Desirable changes in starch and film properties are achieved by physically modifying pinhão starch using HMT, which is a promising alternative to chemical modifications.     

Effect of different ingredients on color and oxidative characteristics of high pressure processed chicken breast meat with special emphasis on use of β-glucan as a partial salt replacer

Color characteristics and oxidative stability of high pressure processed chicken breast meat were studied as a function of various added ingredients such as sodium chloride (NaCl), sodium tripolyphosphate (STPP) and β-glucan (BG). There was an increase in L* value and a decrease in a* value for samples with increase in applied pressure. The additives had little impact on color characteristics in most of the combinations studied. At 40 °C and 600 MPa pressure, expressible moisture of all the samples were not statistically different. SDS PAGE profile of sarcoplasmic proteins revealed a decrease in number of bands in high molecular weight region and an increase in low molecular weight region with increase in applied pressure. Simultaneous application of high pressure and temperature cause breakdown of myosin into its subunits. Carbonyl content of BG samples was lower while treating at 60 °C. Samples with β-glucan showed significantly lower lipid oxidation levels.

Industrial relevance

Preparation of ready to eat gel-type meat products using temperature assisted high pressure processing is still not commercialized. This is basically due to lack of information on the chemistry of food undergoing this process. Increased salt content in modern convenient foods is a major drawback. The results of this experiment showed that high pressure processing and addition of β-glucan can help to partially replace salt addition. In addition, anti-oxidative property of β-glucan in meat system was revealed. This information will help industry to adopt temperature assisted high pressure processing to prepare ready to eat chicken products.     

Consumers’ perception of bakery products with insect fat as partial butter replacement

Including insect ingredients into familiar food products could be a step in enabling a higher acceptance of insects in Western countries. This study investigates the potential of bakery products containing black soldier fly larvae fat (BSF LF) as an ingredient. Sensory and emotional profiling, WTP, liking and product preference were examined for cakes, cookies, and waffles by a total of 344 respondents. Each bakery product was formulated with 0%, 25% and 50% BSF LF as butter substitute. Results showed that BSF LF can replace 25% of butter in these bakery products without changing the overall food experience and liking. In waffles, the substitution might even be up to 50% without influencing consumer’s acceptance. The attributes related to texture and color were hardly affected indicating that this insect fat provides a similar structure and functionality to bakery products as compared with butter. Future research should explore the use of refined BSF LF to reduce off-flavors perceived in formulations containing a higher percentage of insect fat.     

Effect of processing history on the functional and structural characteristics of starch–fatty acid extrudates

Normal maize starch was extruded with and without the addition of fatty acid potassium salts in a twin screw cooker extruder equipped with a slit die rheometer, at 100, 120, 140 or 160 °C barrel temperatures and at screw speeds 20, 91, 161 or 227 rpm. The in line melt viscosity measurements showed that the flow behaviour of the starch system was influenced by the addition of either myristic or palmitic acids used. The examination of functional properties of the extrudates such as bulk density, water solubility index, expansion ratio, degree of gelatinization and water adsorptivity indicated that the addition of fatty acids affected the functionality of starch systems. That is, the extrudate texture became more cohesive and compact whereas the water solubility exhibited by the system was decreased. Structural studies indicated that the crystallinity of starch–fatty acid extrudates was higher than that of the starch systems without fatty acid whereas all extrudates exhibited high glass transition temperatures and their structure was very rigid and brittle.     

Effect of natamycin-containing coating on the evolution of biochemical and microbiological parameters during the ripening and storage of ovine hard-Gruyère-type cheese

The effect of a coating containing natamycin on the ripening course of the hard-Gruyère-type cheese Graviera Kritis was assessed. A single treatment at an early stage of ripening was carried out; samples from natamycin-treated (NT) and control cheeses (CTR) were then taken throughout a 12 month ripening and storage period. Coating gave a statistically significant reduction in the yeasts and moulds counts in the cheese rind. It did not influence the counts and the evolution of the thermophilic bacteria related to starter or of the propionic acid bacteria, nor did it affect the associated aminopeptidase activities. Gross composition of NT cheeses did not differ significantly from that of the control cheeses; the same was also true for proteolysis. Natamycin in the cheese rind after the removal of coating was lower than 0.1 mg dm⁻² at all stages of ripening and no migration to the cheese interior was observed.     

Effect of industrial wood particle size on mechanical properties of?wood-polyvinyl chloride composites

Wood-polyvinyl chloride (PVC) composites were prepared using industrial wood particles used for manufacturing three-layer particleboards. The effect of particle size (0.25–0.5, 0.5–1, 1–2, and 2–4?mm) on the mechanical properties of the composites was investigated. The effect of cross-section size (4×10, 6×15 and 8×20?mm²) of composite pieces made by an injection moulding method was also studied. Both the particle size and specimen cross-section area significantly influenced these properties. The tensile and flexural properties as well as the impact strength in general increased with increasing particle size, and decreased with increasing cross-section size.