Experimental Cheeses Research Articles

Cheese milk low homogenization enhanced early lipolysis and volatiles compounds production in hard cooked cheeses

Homogenization applied to cheese milk has shown to increase lipolysis but its use is not spread as it can induce detrimental effects. The aim of this work was to assess the effect of low-pressure homogenization of the cream followed by pre-incubation of cheese milk on the composition, ripening index, lipolysis and volatile profiles of hard cooked cheeses. For that, control and experimental miniature Reggianito cheeses were made and analyzed during ripening (3, 45 and 90days). Homogenization had no impact on composition and proteolysis. An acceleration of the lipolysis reaction was clearly noticed in cheeses made with homogenized milk at the beginning of ripening, while both type of cheeses reached similar levels at 90days. We found the level of several compounds derived from fatty acid catabolism were noticeably influenced by the treatment applied: straight-chain aldehydes such as hexanal, heptanal and nonanal and methylketones from C5 to C9 were preferentially formed in experimental cheeses.

Enhancement of ester formation in Camembert cheese by addition of ethanol

Ethyl esters are often detected at trace levels in Camembert cheese. This study investigated how the addition of ethanol prior to cheesemaking influenced the composition, texture and flavour profile of Camembert compared to a control cheese manufactured under identical conditions without ethanol. No statistical differences were observed in the composition, microbes or textures of the experimental and control cheeses. However, more ethyl esters and a significantly enhanced fruity flavour perception were reported for the experimental cheeses compared to the control. The addition of 400–1200 μg/g of ethanol may be applied in the production of Camembert cheese to enhance fruity flavour.

Papaya (Carica papaya) latex- an alternative to rennet for cottage cheese preparation

Objective: The study was conducted to standardize the desire level of papaya latex on quality of cheese prepared from cow milk. Materials and methods: Cheese sample was prepared using whole milk collected from Dairy Farm, Bangladesh Agricultural University. This experiment was conducted on five treatments from cow milk named as sample CC1: cow control; A1: 2 drops (0.06 gm); B1: 3 drops (0.10 gm); C1: 4 drops (0.14 gm); D1: 5 drops (0.16 gm) of papaya latex. All experimental cheeses were judged by a panel of judges for organoleptic evaluation using a score card. The total solids and ash content of the different types of cheese were determined by oven drying method according to AOAC. Fat per cent, protein and acidity were determined by Babcock method, procedure and titrating with N/10 sodium hydroxide solution, respectively described by Aggarwala and Sharma. Results: There was significant difference within the overall physical score of different samples except color score. Overall score of sample B1 was highest (93.67±1.53) and score of sample D1 was lowest (72.33±12.01). In case of chemical analysis, the highest protein value was 17.14±0.34% found in B1 and lowest value was 14.94±0.16% found in D1. The highest fat value of sample B1 was 23.00±1.00% and lowest value was 16.00±1.00% found in C1. Highest carbohydrate was found in A1 (9.44±2.25) and lowest in D1 (5.02±0.04). Total solids and moisture content of cheese differed significantly (P

Adjunctive Application of Solid-State Culture Products from Aspergillus Oryzae for Semi-Hard Cheese

To develop a novel type of cheese using Aspergillus oryzae, four strains (AHU 7139, AHU 7140, AHU 7141 and AHU 7146) were tested with respect to their extracellular protease production on solid-state media containing heatdenatured whey protein under various temperatures and pH levels. Proteolytic activity of the crude enzyme extracts was evaluated under acidic condition considering the circumstance of cheese ripening. Zymographic analysis revealed that several kinds of proteases were secreted, which were dependent on the strain, incubation temperature and initial pH value. Using three strains, six types of culture products were selected as adjunctive materials in combination with an incubation temperature of 15 or 20oC and an initial pH condition of 4.0 or 6.5. Gouda-type cheese curd was prepared, and the curd particle received 1% (w/w) of the culture product, followed by pressing, cooling, salting and ripening for 3 months at 11.5oC. An increase in water extractable nitrogen and free fatty acid was observed in some experimental cheeses, depending on the strain and culture history. In particular, incorporation of culture products from A. oryzae AHU 7139, incubated at pH 6.5 and 20oC affected these parameters. As a novel dairy technology, this study propose new insights into the potential use of A. oryzae for providing an enzyme cocktail to develop palatable cheese flavor when suitable strains and culture conditions offer products with an optimum balance of proteases and lipases.

High heat treatment of goat cheese milk. The effect on yield, composition, proteolysis, texture and sensory quality of cheese during ripening

White brined goat cheeses were produced from milk heated to 80 °C/5 min and 90 °C/5 min using an identical cheese making procedure, and they were compared with the control cheese made from milk subjected to common pasteurisation (65 °C/30 min). High heat treatment of goat cheese milk resulted in significant increase of cheese yield. It also significantly affected cheese composition by incorporating higher levels of moisture, fat and whey proteins. The pH values of experimental cheeses decreased during ripening. Degradation of αS-casein was inhibited due to the high heat treatment of milk, while β-casein degradation and secondary proteolysis were not significantly affected. The effect on textural properties was significant, but the same for both experimental cheeses. Contrary to expectations, the cheese obtained from milk heated to 90 °C/5 min received the best scores for sensory characteristics (flavour and texture) at all ripening stages.

EFFECT OF ADDING MICROBIAL LIPASE ON THE ACCELERATION OF UF-RAS CHEESE RIPENING

The effect of adding microbial lipase enzyme to UF cheese milk (0, 50.000, 100.000, and 150.000 lipase units/15kg retentate) on some chemical, rheological, and sensory characteristics of UF-Ras cheese was studied during the 3 months of ripening. The obtained results indicated that lipase enzyme caused a little effect on the gross composition of cheese during ripening. The level of lipolysis and proteolysis were significantly (p < 0.05) higher in the experimental cheeses than those of the control cheese during ripening, which means that there are a positive effect of lipase on ripening time.Lipase addition led to increase the rate of liploysis process about 30 % in 60 days and treated cheeses of this age had TVFA levels typical of 90 days of untreated cheeses. Moreover, enzyme-treated cheese had harder texture than untreated cheeses of the same age. Sensory evaluation showed a significant difference in the total scores of the experimental and control cheeses, with significantly lower-quality scores for the cheeses treated with 100.000 and 150.000 u/15 kg retentate. Cheeses with the highest level of lipase pronounced bitter taste at 60 days of ripening. The most acceptable cheeses were the UF Ras cheese treated with lipase 50.000U/15 kg retentate, which was a slightly similar to the control cheeses at 60 days of ripening.

Genetic diversity, safety and technological characterization of lactic acid bacteria isolated from artisanal Pico cheese

A total of 114 lactic acid bacteria were isolated at one and 21 days of ripening from a traditional raw cow's milk cheese without the addition of starter culture, produced by three artisanal cheese-makers in Azores Island (Pico, Portugal). Identification to species and strain level was accomplished by16S rRNA gene and PFGE analysis. Carbohydrate utilization profiles were obtained with the relevant API kits. Isolates were evaluated according to safety and technological criteria. The most frequently observed genus identified by 16S rRNA sequencing analysis was Enterococcus, whereas API system mostly identified Lactobacillus. The highest percentages of antibiotic resistance were to nalidixic acid (95%), and aminoglycosides (64–87%). All isolates were sensitive to several beta-lactam antibiotics and negative for histamine and DNase production. Gelatinase activity was detected in 49.1% of isolates, 43% were able to degrade casein and 93% were α-hemolytic. Most enterococci presented virulence genes, such as gelE, asaI, ace. Diacetyl production was found to be species dependent and one strain (Leu. citreum) produced exopolysaccharides. Selected strains were further studied for technological application and were found to be slow acid producers in milk and experimental cheeses, a desirable trait for adjunct cultures. Two strains were selected on the basis of technological and safety application as adjunct cultures in cheese production and presented the best cheese aroma and flavor in consumer preference tests. This is the first effort to characterize Pico cheese LAB isolates for potential application as adjunct cultures; the results suggest the potential of two strains to improve the quality of this traditional raw milk product.

Use of an exogenous carboxypeptidase to accelerate proteolysis in Reggianito cheese

The effect of an exogenous commercial carboxypeptidase on the proteolysis of Reggianito cheese was evaluated. Cheeses were manufactured using 4 concentrations of enzyme: 0, 5, 10, and 20 g/100 l milk. Cheese samples were analysed at 0, 60, 90, 120, 150, 180, and 210 days of ripening. Nitrogen content values increased during ripening, but no clear effect due to the enzyme addition was observed. A profound degradation of β-casein was observed during the first 2 months of ripening in cheeses with the highest rates of enzyme addition. An increase of amino acid concentrations was clearly observed in some cheeses manufactured with exogenous enzymes compared with control cheeses at the same ripening time. However, the principal component analysis showed that experimental cheeses had a slight increase in the rate of formation and/or degradation of proteolysis products. Our results represent an important contribution to select new alternatives for enzyme addition during the manufacture of hard cheese.

Variability in chemical and microbiological profiles of long-ripened Caciocavallo cheeses.

Five protected designation of origin (PDO) Caciocavallo Silano and 6 non-PDO Caciocavallo cheeses, ripened for 6mo and collected in the 5 Italian regions of the PDO area (Apulia, Basilicata, Calabria, Campania, and Molise, Italy), were studied to assess their physico-chemical (pH, acidity, moisture, fat, ash, protein, and free amino acid composition) and microbiological profiles. Analyses evidenced a certain fluctuation of previous parameters among samples regardless of the kind of cheese evaluated (PDO and non-PDO). The PCR-denaturing gradient gel electrophoresis analysis performed on the DNA directly extracted from cheeses gave different results, but a low number of bands was always observed. Only one band, corresponding to the species Streptococcus thermophilus, was detectable in 1 PDO and in 2 non-PDO cheese samples, whose free amino acid content was the lowest. Analyses were repeated on experimental Caciocavallo cheeses. Specifically, 2 productions were made, one mimicking the industrial technology (pasteurized milk and selected starter culture) and one the artisanal technology (raw milk and natural whey starter). Results obtained on experimental cheeses at 6mo of ripening showed that industrial samples had lower amounts of total free amino acids then the artisanal ones (1,188.2 vs. 7,523.67mg/100 g of dry matter). Moreover, the PCR-denaturing gradient gel electrophoresis analysis evidenced the sole presence of S. thermophilus in the case of the industrial technology. These data sustain the hypothesis that, out of 11 cheeses analyzed previously, 1 PDO Caciocavallo Silano and 2 non-PDO Caciocavallo cheeses were obtained with the industrial technology. These results could be of help in the discrimination of PDO products, taking into account that the PDO production regulation does not allow the milk pasteurization, nor the use of selected starters.

12S rRNA mitochondrial gene as marker to trace Sicilian mono-species dairy products

For a rapid, specific and sensitive identification of cows', ewes' and goats' milk in mono-species Sicilian dairy products, species-specific duplex-PCR protocol was applied. DNA samples from blood and experimental cheeses of Sicilian autochthonous breeds were extracted to amplify the 12S rRNA (and part of 16S rRNA in case of Ovis aries) mitochondrial species-specific gene fragment. The use of species-specific primers for Bos taurus, Capra hircus and Ovis aries species, after electrophoresis on agarose gel, yielded fragments of 256bp, 326bp and 172bp, respectively. Amplification by duplex-PCR of DNA pools from two species showed detection thresholds of 0.1% of “contaminant” DNA in each mixture. Finally, duplex-PCR assay was applied to experimental cheeses in order to detect the minimum threshold of DNA belonging to one species in cheese made with milk of two species. The results showed a sensitive threshold of 0.1% of ewes' milk in cows' and goats' cheeses, 0.1% of cows' milk in ewes' and goats' cheeses, and finally 0.1% of goats' milk in cows' and ewes' cheeses. The proposed assay represents a rapid and straightforward method of species traceability for the detections of adulteration in Sicilian mono-species dairy products.

Control of oxidation-reduction potential during Cheddar cheese ripening and its effect on the production of volatile flavour compounds.

In cheese, a negative oxidation-reduction (redox) potential is required for the stability of aroma, especially that associated with volatile sulphur compounds. To control the redox potential during ripening, redox agents were added to the salted curd of Cheddar cheese before pressing. The control cheese contained only salt, while different oxidising or reducing agents were added with the NaCl to the experimental cheeses. KIO3 (at 0·05, 0·1 and 1%, w/w) was used as the oxidising agent while cysteine (at 2%, w/w) and Na2S2O4 (at 0·05 and 0·1%, w/w) were used as reducing agents. During ripening the redox potential of the cheeses made with the reducing agents did not differ significantly from the control cheese (E h ≈ -120 mV) while the cheeses made with 0·1 and 0·05% KIO3 had a significantly higher and positive redox potential in the first month of ripening. Cheese made with 1% KIO3 had positive values of redox potential throughout ripening but no starter lactic acid bacteria survived in this cheese; however, numbers of starter organisms in all other cheeses were similar. Principal component analysis (PCA) of the volatile compounds clearly separated the cheeses made with the reducing agents from cheeses made with the oxidising agents at 2 month of ripening. Cheeses with reducing agents were characterized by the presence of sulphur compounds whereas cheeses made with KIO3 were characterized mainly by aldehydes. At 6 month of ripening, separation by PCA was less evident. These findings support the hypothesis that redox potential could be controlled during ripening and that this parameter has an influence on the development of cheese flavour.

Influence of manufacturing conditions on thermo‐physical properties of ripened experimental Emmental‐type cheese and comparison with commercial Emmental cheese

Experimental Emmental cheese was produced at pilot plant scale with varied process conditions, and the ripened cheeses were analysed in terms of thermo‐physical properties. The amount of propionic acid and the temperature at tan δmax ( loss factor) were significantly influenced by varied process parameters. Experimental cheeses were compared to commercial Emmental cheese by the application of principal component analysis. Commercial Emmental cheese was clearly discriminated from experimental Emmental cheese mainly due to the melting behaviour. The results allow the establishment of a small‐scale process for Emmental cheese production to promote product development on a time and cost‐saving level.

Effect of milk pasteurisation and of ripening in a cave on biogenic amine content and sensory properties of a pecorino cheese

Ewes' milk cheeses were evaluated with respect to the influence of pasteurisation and of ripening in a cave on the biogenic amine (BA) content and sensory properties. Both factors significantly influenced the BA content, with higher BA concentrations (on average >1500 mg kg−1 total; 850 mg kg−1 of tyramine) in cheeses manufactured with raw milk and partly ripened in a cave. Milk pasteurisation effectively limited BA formation both qualitatively and quantitatively, but still allowed the accumulation of notable BA levels in cave ripened cheeses. Thus, milk pasteurisation seems not sufficient to guarantee low BA levels in cheeses, particularly when the cheesemaking process employs unconventional ripening conditions. Discriminatory sensory testing showed that the different types of experimental cheeses had detectable sensory differences, although descriptive sensory analysis highlighted few statistically significant differences, mainly due to the effect of the ripening conditions on some texture characteristics and on the aroma intensity.

Effect of reuterin-producing Lactobacillus reuteri coupled with glycerol on the volatile fraction, odour and aroma of semi-hard ewe milk cheese

The effect of the biopreservation system formed by Lactobacillus reuteri INIA P572, a reuterin-producing strain, and glycerol (required for reuterin production), on the volatile fraction, aroma and odour of industrial sized semi-hard ewe milk cheese (Castellano type) was investigated over a 3-month ripening period. The volatile compounds were extracted and analyzed by SPME-GC-MS and cheese odour and aroma profiles were studied by descriptive sensory analysis. Control cheese was made only with a mesophilic starter and experimental cheeses with L. reuteri were made with and without glycerol. The addition of L. reuteri INIA P572 to milk enhanced the formation of six volatile compounds. Despite the changes in the volatile compounds profile, the use of L. reuteri INIA P572 did not noticeably affect the sensory characteristics of cheese. On the other hand, the addition of L. reuteri INIA P572 coupled with 30mM glycerol enhanced the formation of twelve volatile compounds, but decreased the formation of five ones. The use of the biopreservation system did not affect overall odour and aroma quality of cheese although it resulted in a significant decrease of the odour intensity scores. In addition, this cheese received significant higher scores for “cheesy” aroma and significant lower scores for the aroma attributes “milky”, “caramel” and “yogurt-like”. The first two axes of a principal component analysis (PCA) performed for selected volatile compounds and sensory characteristics, accounting for 75% of the variability between cheeses, separated cheeses made with L. reuteri INIA P572 and glycerol from the rest of cheeses, and also differentiated control cheese from cheeses made with L. reuteri INIA P572 from day 60 onward. Our results showed that the reuterin-producing L. reuteri INIA P572 strain, when coupled with glycerol, may be a suitable biopreservation system to use in cheese without affecting odour and aroma quality.

Research of lipolytic processes in functional products made from raw materials of the Carpathian region

The article presents the results of research of lipolytic processes in the production and maturation of Bryndza cheese made from cow, sheep and goat milk, and their mixtures. It has been established that a Bryndza cheese made from goat milk, compared with cheese from cow and sheep milk, and their mixtures contained in 1,77 and 1,99 times more saturated fatty acids, and 1,27 and 1,36 times less unsaturated fatty acids. Peculiarities of accumulation of flavoring substances after the change of technological modes of cheese brining are shown. Experimental cheese samples had a higher content of flavoring substances, volatile organic acids, esters, diacetyl compared to controls, and the highest content of which was observed in the a Bryndza made from goat milk.

Characterization of goat milk from Lebanese Baladi breed and his suitability for setting up a ripened cheese using a selected starter culture

In this work the hygiene and quality parameters of goat milk from Baladi breeds were assess in order to evaluate his suitability for setting up a ripened cheese. Experimental cheese trials were performed on local Lebanese dairy farm using a selected culture starter. Evolution of physicochemical and microbiological features of experimental cheese during ripening were evaluated. Raw milk showed a good microbiological quality meeting the hygiene criteria given by European law on the hygiene of foodstuffs. Mesophilic lactobacilli were found to predominate during cheese fermentation while thermophilic cocci gradually grown and were preponderant during all ripening stage. Non-protein nitrogen and water soluble nitrogen fractions increased gradually over the ripening highlighting good casein primary proteolysis. The Free Fatty Acids (FFA) content increased through the ripening period reaching 7340mg/100g. Palmitic and oleic acids were the most representative long-chain FFAs at 210days whereas capric acid was found as a major short-chain FFA. Cheese ripened 90 days, revealed high score for the flavor and taste attributes and good globally acceptance.

A large factory-scale application of selected autochthonous lactic acid bacteria for PDO Pecorino Siciliano cheese production

The main hypothesis of this study was that the autochthonous lactic acid bacteria (LAB) selected for their dairy traits are able to stabilize the production of PDO (Protected Denomination of Origin) Pecorino Siciliano cheese, preserving its typicality. The experimental plan included the application of a multi-strain lactic acid bacteria (LAB) culture, composed of starter (Lactococcus lactis subsp. lactis CAG4 and CAG37) and non starter (Enterococcus faecalis PSL71, Lactococcus garviae PSL67 and Streptococcus macedonicus PSL72) strains, during the traditional production of cheese at large scale level in six factories located in different areas of Sicily. The cheese making processes were followed from milk to ripened cheeses and the effects of the added LAB were evaluated on the microbiological, chemico-physical and sensorial characteristics of the final products. Results highlighted a high variability for all investigated parameters and the dominance of LAB cocci in bulk milk samples. The experimental curds showed a faster pH drop than control curds and the levels of LAB estimated in 5-month ripened experimental cheeses (7.59 and 7.27 Log CFU/g for rods and cocci, respectively) were higher than those of control cheeses (7.02 and 6.61 Log CFU/g for rods and cocci, respectively). The comparison of the bacterial isolates by randomly amplified polymorphic DNA (RAPD)-PCR evidenced the dominance of the added starter lactococci over native milk and vat LAB, while the added non starter LAB were found at almost the same levels of the indigenous strains. The sensory evaluation showed that the mixed LAB culture did not influence the majority of the sensory attributes of the cheeses and that each factory produced cheeses with unique characteristics. Finally, the multivariate statistical analysis based on all parameters evaluated on the ripened cheeses showed the dissimilarities and the relationships among cheeses. Thus, the main hypothesis of the work was accepted since the quality parameters of the final cheeses were stabilized, but all cheeses maintained their local typicality.

Survival of lactic acid and propionibacteria in low- and full-fat Dutch-type cheese during human digestion ex vivo

The survival of selected bacteria in semi-hard experimental cheeses was studied after exposure to human gastric and duodenal juices in an exvivo model. Experimental cheeses (10 and 28% fat) were supplemented with different strains of Lactobacillus sp. and Propionibacterium sp. and ripened for 7 and 70weeks. After digestion, greater numbers of the adjunct bacteria we rerecorded in the 7-week-old cheeses compared to the well-matured cheeses (70weeks). The bacterial survival was strain dependent, and influenced by the fat content of the cheese. Lactobacilli showed better survival, especially when in low-fat cheeses. The strains of propionibacteria also survived well during the digestion of the low-fat cheeses. The results confirmed that cheese can potentially be a good carrier matrix for bacteria to the intestine. In addition, it has been shown that different strains present in cheese have different abilities to survive the conditions of the gastrointestinal tract. Younger cheese was indicated to be a better carrier, possibly because the bacteria present in those cheeses have had shorter exposure to the stress conditions occurring in cheese during prolonged maturation. Cheese can function as a suitable vehicle for the delivery of a variety of food-related micro-organisms to the intestine. Young cheese as well as low-fat cheeses are better carrier matrixes than full-fat and/or more well-ripened cheeses. Most of the lactobacilli and all the propionibacteria survived well during digestion of the low-fat cheeses. This study also showed the ability of cheese lactobacilli and PAB to survive the severe conditions of GIT.

Use of Smart Nose and GC/MS/O analysis to define volatile fingerprint of a goatskin bag cheese “Bouhezza”

Bouhezza is an Algerian ripened cheese manufactured specifically in a goatskin bag with “Lben”, salt and raw milk for several weeks. The aim of this study was to characterize the unknown aromatic profile of the Bouhezza using SMart Nose, gas chromatography/mass spectrometry (GC/MS) and GC/MS/Olfactometry. In a first step, four farmhouse Bouhezza cheeses were analyzed by SMart Nose and by GC /MS to investigate volatile profile at 75 and 150 ripening days. In a second step, two Bouhezza cheeses produced under controlled conditions according to the traditional process were analyzed during manufacturing-ripening by GC/MS/Olfactometry, to detect odor active compounds changes. Results showed higher variability of volatiles in cheeses at 75 days ripening compared to 150 days. Farmhouse and experimental cheeses showed esters the most abundant volatile compounds detected with GC/MS and GC/MS/Olfactometry. Ten odor active compounds were common between cheeses whatever is the origin or the age. These compounds can be considered as marker of the aromatic profile of Bouhezza cheese, not yet established.

An analytical approach to reveal the addition of heat-denatured whey proteins in lab-scale cheese making

A simple analytical procedure for the detection of self-aggregated heat-denatured whey proteins (HDWP) in model cheeses was developed. The principle of the approach lies in the solubilization of the cheese matrix by a sodium citrate solution (0.2 M, pH 7.0) resulting in the dissociation of the casein micelles and the insolubilization of HDWP aggregates, which are collected in the pellet after a centrifugation step. The reliability of the procedure was tested in lab-scale cheeses from peroxidase-positive pasteurized milk with different protein-based ingredients (microparticulated whey protein concentrate, milk protein concentrate, whey protein isolate and Ricotta cheese) at concentrations ranging from 0.2 to 1.2% protein (w/v on cheese milk). A linear relationship between the amount of the HDWP added to cheese milk and that recovered from model cheeses was observed. Heat-damage indicators, furosine and lysinoalanine, showed levels in the experimental cheese samples not related with added HDWP, but represented a source of information on the ingredients other than liquid milk. Overall, in the model cheeses, the proposed method was an easy-to-apply and reliable tool for the evaluation of the presence of HDWP-based products. Further investigation is required for the application to real cheeses and for the evaluation of possible interferences from proteolysis during ripening.