Soft Goat Cheese Research Articles

Propionic acid production from food waste in batch reactors: Effect of pH, types of inoculum, and thermal pre-treatment

In this study, lab-scale batch fermentation tests were carried out at mesophilic temperature (30 °C) to examine the influence of inoculum type, pH-value, and thermal pretreatment of substrate on propionic acid (PA) production from dog food. The selected inocula comprised a mixed bacterial culture, milk, and soft goat cheese. The batch tests were performed at pH 4, pH 6, and pH 8 for both, untreated and thermally pretreated food. Results show that the production of PA and volatile fatty acids (VFAs) in general were significantly dependent on the chosen inoculum and adjusted pH value. The maximum PA production rates and yields were determined for the cheese inoculum at pH 6 using untreated and pretreated dog food. PA concentration reached 10 gL−1and 26.5 gL−1, respectively. Our findings show that by selecting optimal process parameters, an efficient PA production from model food waste can be achieved.

Survival of spray-dried and free-cells of potential probiotic Lactobacillus plantarum 564 in soft goat cheese.

A high viability of probiotics in food product, with a living cells threshold of 107 /cfu/g (colony-forming units/g) is a challenge to achieve in food production. Spray drying is an efficient and economic industrial method for probiotic bacterial preservation and its application in food products. In this study, the survival of free and spray-dried cells of potential probiotic strain Lactobacillus plantarum 564 after production and during 8weeks of storage of soft acid coagulated goat cheese was investigated, as well as compositional and sensory quality of cheese. Total bacterial count of spray-dried Lb. plantarum 564 cells were maintained at the high level of 8.82log/cfu/g in cheese after 8weeks of storage, while free-cell number decreased to 6.9log/cfu/g. However, the chemical composition, pH values and sensory evaluation between control cheese (C1 sample made with commercial starter culture) and treated cheese samples (C2 and C3, made with the same starter, with the addition of free and spray-dried Lb. plantarum 564 cells, respectively) did not significantly differ. High viability of potential probiotic bacteria and acceptable sensory properties indicate that spray-dried Lb. plantarum 564 strain could be successfully used in the production of soft acid coagulated goat cheeses.

Reducing Goat milk Flavor by Beta – Cyclodextrin (β-CD) and its Effect on Texture and Microstructure in Soft Goat Cheese

Reducing Goat milk Flavor by Beta – Cyclodextrin (β-CD) and its Effect on Texture and Microstructure in Soft Goat Cheese

Fish Oil Fortification of Soft Goat Cheese

Soft goat cheese was fortified with four levels of purified fish oil (0, 60, 80, and 100 g fish oil per 3600 g goat milk) prior to curd formation to deliver high levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) per serving. The cheese was evaluated for proximate composition, EPA+DHA content, oxidative stability, color, pH, and consumer acceptability. The cheese was partially vacuum packed and stored at 2 °C for four weeks. The fat content was significantly (p < 0.05) higher in the fortified treatments compared to the control, but was not significantly different among fortified treatments. Likewise, EPA+DHA contents were not significantly different among fortified samples, averaging 127 mg EPA+DHA per 28 g serving. No significant lipid oxidation was detected by thiobarbituric acid reactive substances (TBARS) or hexanal and propanal headspace analyses over the four week refrigerated shelf-life study for any treatments. The fortified cheeses were all liked 'moderately' by consumers (n = 105) for overall acceptability, although the 60 g fortification level did rate significantly higher. The control cheese and the 60 g fortification level had no significant differences in consumer purchase intent. These results demonstrate that fortification levels of up to 127 mg EPA+DHA per serving may be added to soft cheese without negatively affecting shelf-life or consumer purchase intent. Omega-3 fatty acids have been shown to have strong associations with health and well-being, and fish oil is a rich source of these fatty acids. In this study, goat cheese was successfully fortified to deliver 127 mg omega-3 fatty acids per 28 g serving without affecting shelf life or consumer purchase intent.

Antioxidant activity, bioactive polyphenols in Mexican goats' milk cheeses on summer grazing

Two feeding systems trials were carried out to determine the antioxidant activity of soft goats' milk cheeses, and also to evaluate the presence of bioactive polyphenolic compounds. Two groups (A and B), each one with 20 (BW 50+/-5 kg) French Alpine goats were employed. All animals had between 70 to 80 milking days and were milked once a day. Group A included daily grazing on shruby rangeland vegetation, and group B was kept in full indoor confinement. Thirty kg of goats' milk from each group were collected; 15 kg from each were pasteurized and the remaining 15 kg were not pasteurized (raw), resulting in four treatments (two feeding system x two milk treatments). Soft goat's cheese antioxidant activity can be modified by the animals feeding system; grazing management represents a better option than indoor feeding to produce a healthy profile of bioactive compounds; providing an increase of total polyphenol, hydroxycinnamic acids and flavonoid concentrations. Pasteurization did have a significant effect on these metabolites, and diminished total polyphenol concentration. More research is needed to elucidate the potential of soft goat's cheese as a functional food.

Rheological characteristics of goat and sheep milk

Rheology represents the properties of both solid and liquid foods, where texture is the rheology related to solid foods, and viscosity is the rheology of fluid foods. Three categories of tests measure textural characteristics of solids foods, empirical (ball compressor, penetrometer, curd tension meter), imitative (texturometer, texture profile analysis [TPA]), and fundamental tests (small amplitude oscillatory shear analysis [SAOSA], torsion analysis [TA]). Regardless of animal species, milk casein gels are mainly responsible for the rheological properties of cheese and other dairy products. In normal fluid milk, the viscosity is affected by the state and concentrations of fat, protein, temperature, pH, and age of the milk. Average milk viscosity has been determined for goats at 2.12 cPas, sheep 2.48 cPas, camels 2.8 cPas, buffaloes 2.2 cPas, and cows 1.7 cPas. Heating decreases the dynamic viscosity, but it increases at the point of coagulation. Sheep and goat milk have the same proteins as cow milk, but their proportions and genetic polymorphs differ widely, which explains different rennetabilities and considerable rheological variations in cheesemaking. Casein micelle structure is similar in goat, sheep, and cow milk, but differs in composition, size and hydration. Sheep milk has caseins richer in calcium than cow caseins, it is also very sensitive to rennet, because of higher β/α s-casein ratio, and coagulation proceeds faster than in cow milk. Rheological studies with Monterey Jack cheese from goat milk found “knitting” with progressing aging time, less hardness, less shear stress values, and more rubberiness. High correlations were noted between SAOSA scores and proteolysis in cheeses. Terrincho sheep cheese showed increased hardness, fracturability, gumminess, chewiness, yelloweness, decreased adhesiveness, resilience, and cohesiveness during ripening. Frozen storage of soft goat cheeses had minimal effects on textural qualities, which has valuable market implications. Feta cheeses showed increased compactness and porosity, when goat milk had been added to sheep milk. Yogurt studies, including Labneh from the Middle East, found highest viscosity for sheep followed by goats, cows, and camels, and viscosity increased with solids contents. Three different transient viscosity stages were described mathematically, and camel milk varied least in viscosity during yogurt gelation. Viscosity decreased with increasing angular velocity of the inner cylinder, suggesting that yogurt behaved as a shear-thinning non-Newtonian fluid. Rheological properties are important monitors of quality control in dairy processing and in scientific research.

Microbiological characteristics of Crottin goat cheese made in different seasons

General profiles and effect of season on microbiological characteristics of Crottin goat's cheese were evaluated in different batches during storage. Microorganisms determined were: mesophilic, proteolytic, halotolerant, psychotrophs, coliforms, yeasts and Staphylococcus aureus. The presence of Escherichia coli, Salmonella spp., Yersinia enterocolitica and pH and moisture content were also analyzed. E. coli, Salmonella spp. and Y. enterocolitica were not detected in the Argentinian soft goat cheese. Cheese made during winter had significant differences in mesophilic, psychrotrophics, halotolerant microorganisms and yeast between batches. In fall cheese, there were significant differences to mesophilic, proteolytic and psychrotrophics. There were not significant differences to the microbial groups in summer cheese. The variability between batches in Crottin cheese occurred during cold months, which may be attributed to the coagulation process of the cheese at environmental temperature (without any control), creating a delay in the lactic flora activity in winter. The results showed a significant influence of the seasons in the microbial population evolution during storage, suggesting that the differences in each microbial group in different seasons could be caused by differences in the predominant strains of each group. Further studies are needed for the composition of the microorganisms, where goat's products have not specific hygienic and quality standards in Argentina.

Effect of 3 months frozen-storage on organic acid contents and sensory properties, and their correlations in soft goat milk cheese

Organic acid concentrations and sensory properties, and correlations between the two parameters for soft goat milk cheeses were evaluated throughout 3 months of frozen-storage. Three different lots of commercial soft goat cheeses were purchased, and subdivided into three equal portions. One portion was stored at 4 °C as the non-frozen control and the other two were immediately frozen (−20 °C) for 0 and 3 months, then subsequently thawed the next day at 4 °C and stored at 4 °C for 0, 14 and 28 days. Organic acids were analyzed using a HPLC (Hewlett Packard; LC-1100 Series). Descriptive sensory properties were evaluated by a trained panel, and flavors and tastes were scored on a 10-point Spectrum™ intensity scale. Results showed that tartaric, citric, uric and propionic acids in the soft goat cheese tended to increase after 3 months frozen-storage, while formic and malic acids decreased, and pyruvic acid was absent. Initial sensory properties of goat cheeses through 3 months frozen-storage were not changed in comparison of non-frozen fresh cheeses. However, cooked/milky, whey, milkfat, diacetyl and sweet, sour, and salty tastes diminished with prolonged refrigerated aging time for all frozen-storage regimes, while brothy, yeasty, and oxidized flavors increased. Some correlations ( r) between organic acids and sensory properties were observed, including r-values between tartaric acid and goaty/waxy flavor, formic acid and sour taste, malic acid and cooked milky flavor, acetic acid and saltiness, citric acid and whey flavor, propionic and brothy or oxidized flavor, and some unknown acids with milk fat lactone flavor.

Changes in the microflora of commercial soft goat milk cheese during refrigerated and frozen-storage

Three batches of commercial soft goat cheese were divided into fresh-unfrozen, 3 and 6 months frozen-storage treatment groups. All groups were stored refrigerated at 4 °C for 0, 14 and 28 days. Microbiological contents of the cheeses, including total aerobes, Escherichia coli, coliforms, Staphylococcus aureus, yeast and mold levels were determined using Petrifilm plate counts techniques. Mean total plate count (TPC), yeast and mold counts of the initial unfrozen cheese for 0 day storage at 4 °C were 5.58, 5.16 and 4.47 log cfu/g, respectively. The TPC, yeast and mold counts after 6 months frozen-storage and 0 day storage at 4 °C were 5.86, 3.70 and 3.00 log cfu/g, indicating that significant reductions of yeast and mold counts occurred during frozen-storage. These microbial populations gradually decreased during subsequent aging in refrigerated storage at 4 °C for 14 and 28 days. No detectable levels of E. coli, coliform, and S. aureus counts were found in the fresh, or frozen samples. It was concluded that commercially marketed soft goat milk cheeses were free of pathogenic bacteria, and the present study confirmed that consumers may purchase fresh and frozen-stored goat cheese products without food safety concerns.

Changes in the microflora of commercial soft goat milk cheese during refrigerated and frozen-storage

Three batches of commercial soft goat cheese were divided into fresh-unfrozen, 3 and 6 months frozen-storage treatment groups. All groups were stored refrigerated at 4 °C for 0, 14 and 28 days. Microbiological contents of the cheeses, including total aerobes, Escherichia coli, coliforms, Staphylococcus aureus, yeast and mold levels were determined using Petrifilm plate counts techniques. Mean total plate count (TPC), yeast and mold counts of the initial unfrozen cheese for 0 day storage at 4 °C were 5.58, 5.16 and 4.47 log cfu/g, respectively. The TPC, yeast and mold counts after 6 months frozen-storage and 0 day storage at 4 °C were 5.86, 3.70 and 3.00 log cfu/g, indicating that significant reductions of yeast and mold counts occurred during frozen-storage. These microbial populations gradually decreased during subsequent aging in refrigerated storage at 4 °C for 14 and 28 days. No detectable levels of E. coli, coliform, and S. aureus counts were found in the fresh, or frozen samples. It was concluded that commercially marketed soft goat milk cheeses were free of pathogenic bacteria, and the present study confirmed that consumers may purchase fresh and frozen-stored goat cheese products without food safety concerns.

Soft goat cheeses at different ripening stages: cheese structure, composition and non solvent water

Soft goat cheeses of the Sainte-Maure variety were studied at different ripening stages to characterise their microstructure in relation to their composition and water content. The intemalliq- uid phase of the cheeses was extracted by hydraulic pressure and analysed. Non solvent water (NSW) in cheese was calculated according to the method of van Boekel and Walstra from the concentration of sorne completely dissolved components such as potassium (K), sodium (Na) or 13-lactoglobulin (I3-Lg) in the liquid fraction compared to that in the whole cheese. The values obtained for NSW in the 7-d-old cheeses were 1.1, 0.8, 2.1 ss:' casein (CN) for K, Na and I3-Lg, respectively. A reduc- tion in NSW values was observed during ripening, down to 0.6 gg CN for K and Na and 1.3 ss:' CN for I3-Lg in the 58-d-old cheese. Total water content of cheese decreased during ripening from 4.7 to 1.9 g.g-I CN, so that the relative proportion of NSW to total water increased during ripening. Very different cheese microstructures were observed at the beginning and end of the ripening period. In the early stage of ripening the structure of cheese was loose, characterised by accelerated enzymatic reactions which developed in the aqueous phase as a result of proteolysis. A rapid decrease in the water content occurred due to evaporation at the cheese surface, facilitated by the easy movement of water from the inner part of cheese to the surface through the open and porous structure. During these early stages of ripening, pressing of the cheese led to high flow rates of Iiquid. When cheese total solids reached 600-650 g·kg-1, which occurred after -43 d of ripening, the cheese microstructure became more compact. The residual water had a slower diffusion rate in the structure, as indicated by the lower variation in the cheese water content with time. Residual water was mainly non solvent. The prote- olytic rate in the cheeses decreased, probably due to the lower content in solvent water. The kinetics of the pressing at this stage was characterised by a low flow rate. © InraJElsevier, Paris. goat cheese 1non solvent water 1hydraulic pressing 1desorption 1structure

Characterization of aroma compounds in the volatile fraction of soft goat cheese during ripening

A traditional Sainte-Maure soft cheese was analyzed from 2 days to 31 days of ripening for ils gross composition, total and free fatty acid distribution and the aroma cornpounds in the volaiile fraction of cheese, which were studied by gas chromatography coupled with mass spectrometry. Cheese ripening was characterized by a very low level of casein proteolysis, 5%, which was hydrolyzed in low molecular mass peptides, and by a high lipolysis level, up to 6% of free to total fatty acids at the end of ripening. The volatile fraction of cheese was studied using gas chromatography coupled with mass spectrometry. Among the 38 compounds identified in the volatile fraction, seven were characterized by olfactometry as having a specifie cheese or goat cheese aroma. They were: hexanoic, octanoic, nonanoic, decanoic 3-methylbutanoic, 4-methyl- octanoic and 4-ethyloctanoic. Sorne acids were present at levels higher than their threshold value (TV) even in 2-day cheeses, while sorne others only reached their TV in the 31-day cheeses, showing that the flavor of ripened cheeses was different from that of fresh cheeses. © InralElse- vier, Paris. goat cheese 1ripening 1aroma compound

Incidence des traitements technologiques sur la qualité hygiénique du lait et des fromages de chèvre à pâte molle

and on soft goat's cheeses. The aims of this study were first/y to compare the reduction in contaminant flora when pasteurization (70°C for 5 min) or microfiltration (1.4 um pore size) are applied to goat's milk, second/y the acidification kinetics of both mi/ks compared to that of raw milk, and third/y the deve/opment of contaminant faeca/ coliforms and staphylococci during the making and ripening of 2 types of goat's cheese: /actic and rennet curds. Pasteurization and microfiltration were found to significantly reduce the contaminant flora in goat's milk. Staphylococcal flora were reduced respectively by 1.4 and 1.1 Log units (P < 0.001) and faeca/ coliforms by 1.4 and 1.0 Log units (P < 0.05) respectively. Development of contaminant flora during milk acidification at 22°C was inverse/y proportiona/ to the initial level of /actic flora. Acidification rate was highest in raw milk, intermediate in pasteurized milk and lowest in microfiltrated milk. Botn pasteurized and microfiltrated milks a/lowed a higher deve/opment of contaminant flora than raw milk in the drained curds; these differences were

A ripening and storage study of soft goat cheese with Penicillium candidum on the surface

The present study analyzed physico-chemical characteristics, proteolysis, and lipolysis over a 14-day ripening period and a 14-day storage period in two batches of industrially produced goat cheese with Penicillium candidum on the surface. After the 28 days the pH inside the cheese was considerably lower than that on the surface, due to the activity of the moulds. At the end of the study the water-soluble nitrogen was 16% of the total nitrogen, and 84% of the water-soluble nitrogen was non-protein nitrogen. Degradation of α s and β-caseins was low, but at the end of the storage period a series of bands, chiefly degradation products of β-casein, was observed in the γ-casein region; weak bands with higher electrophoretic mobility than that of α s-casein were also found. Electrophoretic analysis of the water-soluble protein fraction showed no variation. No change in the triglyceride fatty acid composition was observed during the study period. The total free fatty acid content increased from 9 881 to 12 137 ppm.