Use of wild Lactobacillus strains in an adjunct culture for a Roncal-type cheese

The effect of an added adjunct culture consisting of facultatively heterofermentative lactobacilli (FHL) on the volatile compounds and sensory characteristics of a Spanish ewes'-milk cheese was examined. Three cheese batches were prepared using a commercial starter, one from raw milk, another from pasteurized milk, and a third from pasteurized milk with an added culture of wild Lactobacillus. paracasei+Lb. plantarum. Analysis of the volatile compounds was carried out by the purge and trap method and gas chromatography with a mass spectrometer and disclosed a total of 86 compounds belonging to the chemical families hydrocarbons, fatty acids, esters, ketones, aldehydes, and alcohols. After ageing for 120 and 240 days, the cheese samples underwent sensory analysis by a panel of expert assessors. The attributes evaluated were characteristic odour and odour intensity and characteristic aroma and aroma intensity. Pasteurization of the milk had an effect on the formation of certain volatile compounds, adversely affecting the characteristic flavour of the cheese. Use of the adjunct culture in addition to the commercial starter improved the flavour of the cheese made from the pasteurized milk, which earned sensory scores similar to those awarded to the cheese made from the raw milk. Use of adjunct cultures consisting of indigenous FHL strains could help to conserve the traditional characteristics of Roncal cheese made from pasteurized milk, although some technical adjustments to the Regulations would be needed.     

Volatile fraction and sensory characteristics of Manchego cheese. 1. Comparison of raw and pasteurized milk cheese

Manchego cheese can be manufactured from raw or pasteurized ewes' milk. An automatic purge and trap apparatus, coupled to a GC-MS was used to isolate. identify and compare the relative amounts of the volatile components of raw and pasteurized Manchego cheese during ripening. The majority of volatile compounds were more abundant in raw milk (RM) cheeses than in pasteurized milk (PM) cheeses. Alcohols and esters predominated in the profile of RM Manchego cheese, while methyl-ketones and 2,3-butanedione were quantitatively important in PM cheeses. Branched chain alcohols were much more abundant in RM cheeses. The discriminant analysis separated 100% samples into RM or PM cheeses by using only 16 volatile compounds. Aroma intensity was correlated with esters, branched chain aldehydes and branched chain alcohols in RM cheeses, and with esters, branched chain aldehydes, 2-methyl ketones and 2-alkanols in PM cheeses. Diacetyl was positively correlated with the aroma attribute 'toasted' and negatively correlated with aroma quality in PM cheeses.     

Volatile composition and sensory properties of industrially produced Idiazabal cheese

The volatile composition and sensory properties of industrially produced Idiazabal cheeses made from ewes’ raw milk (RM) or pasteurised milk (PM) and with addition of different starter cultures were compared. Cheeses were analysed at 90 and 180 d of ripening. Acids were the major volatile compounds in RM cheeses. Methyl ketones were the major volatile compounds in PM cheeses at 90 ripening days. However, the content of acids strongly increased with ripening whereas the content of ketones decreased in PM cheeses. The concentration of esters was higher in RM cheeses than in PM cheeses. No differences were found in the content of alcohols. Most aldehydes, hydrocarbons, terpenes and furans identified were minor volatile compounds in both RM and PM cheeses. In RM cheeses, characteristic sensory attributes for the aroma of Idiazabal cheese were present at 3 months, whereas in PM cheeses those desirable sensory attributes did not appear until 6 months of ripening.     

The effects of starter culture on chemical composition, microbiological and sensory characteristics of Turkish Kaşar Cheese during ripening

Kaşar cheese samples were produced from raw milk and starter culture-added pasteurized milk. Chemical, microbiological and organoleptic properties of kaşar cheeses were analysed at certain times during the ripening periods (on the 1st, 7th, 15th, 30th, 60th, 90th days). Generally, chemical parameters were not affected by starter culture. The pH, ripening index, water-soluble nitrogen and non-protein nitrogen did not show significant differences between the cheese samples. The addition of starter affected the microbiological quality of the cheeses. Starter culture-added kaşar cheeses contained low levels of total aerobic mesophilic bacteria, moulds and yeasts, and coliforms, and achieved higher organoleptic scores than those of cheeses made from raw milk. The starter cultures contributed to acidity and microbial quality of the cheese.     

High-Pressure Treatment and Freezing of Raw Goat Milk Curd for Cheese Manufacture: Effects on Cheese Characteristics

High-pressure treatment of raw goat milk curd was investigated as an alternative to thermal treatment of milk in cheese manufacture, and curd freezing as a procedure to surmount the seasonality of goat milk production. Experimental cheeses were made by mixing (70:30) fresh cow milk curd with frozen curd from pasteurized goat milk (PGC), frozen curd from raw goat milk (RGC), or frozen pressurized curd from raw goat milk (PRGC). Control cheese was made from a mixture (70:30) of pasteurized cow and goat milk. RGC cheese showed the highest counts of staphylococci, Gram-negative bacteria and coliforms, whereas PRGC cheese had maximum aminopeptidase activity, esterase activity, and overall proteolysis. Control cheese exhibited the highest dry matter content and peptide levels, the lowest concentration of free amino acids, the highest concentration of volatile compounds such as free fatty acids, alcohols and esters, and the firmest texture. Differences in sensory characteristics between experimental and control cheeses were of minor importance. High-pressure treatment of curd allowed the production of cheese of bacteriological quality similar to that of control cheese made using pasteurized milk, while curd freezing did not alter the sensory characteristics of experimental cheeses with respect to control cheese.     

Effect of milk pasteurization and acidification method on the chemical composition and microstructure of a Mexican pasta filata cheese

Four Mexican pasta filata cheese variations were prepared using raw milk and starter culture (RMSC), raw milk and acetic acid (RMAA), pasteurized milk and starter culture (PMSC), and pasteurized milk and acetic acid (PMAA). Chemical composition, yield and microstructure were evaluated. Scanning electron micrographs of the cheese variations were evaluated by lacunarity analysis. PMSC and PMAA cheeses had higher protein, moisture and yield, but lower calcium content than RMSC and RMAA cheeses. The manufacturing conditions and refrigerated storage produced structural differences in the cheese variations, which displayed different heterogeneity patterns arising from spatial distribution of their components as determined by lacunarity analysis. Raw and pasteurized milk cheese variations showed an opposite lacunarity pattern trend during storage time.     

Effect of addition of native cultures on characteristics of Armada cheese manufactured with pasteurized milk: A preliminary study

Six batches of Armada cheese were produced, one from raw milk with no added starter, another from pasteurized milk with a commercial mesophilic starter and four from pasteurized milk with experimental starters. These starters included: Lactococcus lactis subsp. lactis and L. lactis subsp. lactis biovar. diacetylactis; or the same strains plus either Enterococcus raffinosus, Leuconostoc mesenteroides subsp. dextranicum or Lactobacillus plantarum, all isolated from Armada cheese made from raw milk. The highest counts of aerobic mesophilic bacteria and populations of lactic acid bacteria for all batches were reached in the first week of ripening. These counts declined later throughout the ripening, although not at identical rates in every batch. Counts of lactobacilli were significantly higher in cheeses made from raw milk and those inoculated with the lactobacilli strain than in the other batches, over the whole ripening period. Added native starters minimized growth of Enterobacteriaceae. Cheeses made with the starter containing the Enterococcus strain had the most favourable sensory attributes throughout ripening.     

Sensory Changes During Ripening of Raw Ewes' Milk Cheese Manufactured With and Without the Addition of a Starter Culture

ABSTRACT: This study characterizes and compares the sensory aspects of raw ewes' milk cheeses manufactured with and without the addition of a starter culture using specifically developed sensory terminology. Furthermore, overall organoleptic quality was assessed at each ripening stage. Two different raw ovine milk cheese batches were manufactured with and without the addition of a freeze-dried starter. Sensory differences in odor, flavor, and texture were related to starter and raw milk flora activities during manufacturing and ripening. Cheeses made with the addition of a starter culture were scored higher by quality experts. Cheeses manufactured without a starter culture received higher scores for dirty and animal attributes, such as rennet, butyric, sharp, pungent, and brine, possibly related to lower quality scores. Conclusions reached in the present study coincide with previous ones; however, by using a sensory lexicon specifically developed for ewes' milk cheeses, it has been possible to describe slight and specific differences in the cheeses.     

Lipolysis in Urfa cheese produced from raw and pasteurized goats’ and cows’ milk with mesophilic or thermophilic cultures during ripening

Lipolysis was evaluated in Urfa cheese made from raw and pasteurized goats’ and cows’ milk with mesophilic or thermophilic cultures. The acid degree values (ADVs) of the cows’ milk cheeses were significantly (P < 0.05) higher until 60 d of storage than that of cheese made from goats’ milk. Total free fatty acid (FFA) contents of goats’ milk cheese were significantly (P < 0.001) lower than that of cows’ milk cheese throughout ripening, whereas goats’ milk cheese flavour was higher (P < 0.05) than cows’ milk cheese. Pasteurization of milk prior to cheese-making has a negative influence, not only on the level of lipolysis throughout ripening, but also on the relative amounts of short chain FFAs and sensory properties of the cheeses (P < 0.001). Cheese produced without starter bacteria underwent significantly (P < 0.05) higher lipolysis than cheeses produced with mesophilic or thermophilic starter bacteria, while cheese made with thermophilic starter culture had similar flavour to cheese made without starter culture.     

Evaluation of biogenic amines and microbial counts throughout the ripening of goat cheeses from pasteurized and raw milk

The effect of the hygienic quality of milk on changes in microbial counts and biogenic amine content was evaluated during ripening of goat cheeses manufactured from pasteurized and raw milks at 1, 14, 30, 60 and 90 d. The original milk, rennet, curd and whey were also included in the study. The pH, salt content and extent of proteolysis in the cheese were also evaluated. Spermidine and spermine were the main amines in raw milk, while they were minor amines in cheeses. Other amines increased markedly during ripening, tyramine being the main amine in cheese made from raw milk and cadaverine and putrescine in those produced from pasteurized milk. Enterobacteriaceae counts decreased during ripening whereas those of lactic acid bacteria increased, especially lactobacilli and enterococci. Cheese made from raw milk showed higher microbial counts during ripening than those made from pasteurized milk, especially for Enterobacteriaceae and enterococci, counts being 2 or 3 log units higher. Raw milk cheese showed remarkably higher biogenic amines compared with pasteurized milk cheeses. Therefore, pasteurization of milk causes a decrease in final biogenic amine content of cheese as a result of the reduction of its microbial counts.     

Influence of ripening temperature on the volatiles profile and flavour of Cheddar cheese made from raw or pasteurised milk

Cheddar cheeses were made from raw (R1, R8) or pasteurised (P1, P8) milk and ripened at 1°C (P1, R1) or 8°C (P8, R8). Volatile compounds were extracted from 6 month-old cheeses and analysed, identified and quantified by gas chromatography-mass-spectrometry. A detailed sensory analysis of the cheeses was performed after 4 and 6 months of ripening. The R8 cheeses had the highest and P1 the lowest concentrations of most of the volatile compounds quantified (fatty acids, ketones, aldehydes, esters, alcohols, lactones and methional). The R8 and P8 cheeses contained higher levels of most of the volatiles than R1 and P1 cheeses. Ripening temperature and type of milk influenced most of the flavour and aroma attributes. Principal component analysis (PCA) of aroma and flavour attributes showed that P1 and R1 had similar aroma and flavour profiles, while R8 had the highest aroma and flavour intensities, highest acid aroma and sour flavour. The age of cheeses influenced the perception of creamy/milky and pungent aromas. PCA of the texture attributes separated cheeses on the basis of ripening temperature. The R8 and P8 cheeses received significantly higher scores for perceived maturity than P1 and R1 cheeses. The P1 and R1 cheeses had similar values for perceived maturity. In a related study, it was found that concentrations of amino acids and fatty acids were similar in R1 and P1 during most of the ripening period, and R1 and P1 cheeses had low numbers of non-starter lactic acid bacteria (NSLAB). The panel found that ripening temperature, type of milk and age of cheeses did not influence the acceptability of cheese. It is concluded that NSLAB contribute to the formation of volatile compounds and affect the aroma and flavour profiles and the perceived maturity of Cheddar cheese.     

Proteolysis during ripening of Manchego cheese made from raw or pasteurized ewes' milk. Seasonal variation

Changes in nitrogen compounds during ripening of 40 batches of Manchego cheese made from raw milk (24 batches) or pasteurized milk (16 batches) at five different dairies throughout the year were investigated. After ripening for six months, degradation of p-kappa- and beta-caseins was more intense in raw milk cheese and degradation of alpha(s2)-casein in pasteurized milk cheese. Milk pasteurization had no significant effect on breakdown of alpha(s1)-casein. Hydrophobic peptide content did not differ between raw and pasteurized milk cheese, whereas hydrophilic peptide content was higher in raw milk cheese. There were no significant differences between seasons for residual caseins, but hydrophobic peptides were at a higher level in cheese made in autumn and winter and hydrophilic peptides in cheese made in winter and spring. Raw milk cheese had a higher content of total free amino acids and of most individual free amino acids than pasteurized milk cheese. The relative percentages of the individual free amino acids were significantly different for raw milk and pasteurized milk cheeses. The relative percentages of Lys and lie increased, while those of Val, Leu and Phe decreased during ripening. There were also seasonal variations within the relative percentages of free amino acids. In raw milk cheeses, Asp and Cys were relatively more abundant in those made in autumn, Glu and Arg in cheeses made in winter, and Lys and Ile in cheeses made in spring and summer. Biogenic amines were detected only in raw milk cheese, with the highest levels of histamine, tryptamine and tyramine in cheeses made in spring, winter and spring, respectively.     

Comparison of the volatile profiles of Arzúa-Ulloa and Tetilla cheeses manufactured from raw and pasteurized milk

Levels of volatile compounds in Arzúa-Ulloa and Tetilla cheeses manufactured from raw and pasteurized milk were investigated. Analysis of volatile compounds in six raw milk (RM) starter-free cheeses (15–45 days old) and six pasteurized milk (PM) cheeses made with deliberately added starters (15–45 days old) manufactured in different dairies, was performed on an automatic dynamic headspace apparatus coupled to a GC/MS. The volatile fraction of RM cheeses displayed 46 volatile compounds (34 for PM cheeses) including fatty acids, esters, aldehydes, alcohols, ketones, hydrocarbons and sulphur compounds. Fatty acids and several esters were only detected in RM cheeses. Moreover, the highest contents of methylketones, secondary alcohols and branched-chain aldehydes and alcohols were also observed in RM cheeses. All results confirm more intense lipolysis in RM cheeses than in PM cheeses. In addition, branched-chain aldehydes and alcohols were significantly more abundant in RM than in PM cheeses, which indicates that catabolism of branched-chain amino acids was significantly higher in RM cheeses. This study has provided useful information which will allow the selection of starter and non-starter bacteria more suitable for manufacturing Arzúa-Ulloa and Tetilla pasteurized milk cheeses with organoleptic characteristics similar to those of traditional raw milk cheeses.     

Volatile composition and improvement of the aroma of industrial Manchego cheese by using Lactobacillus paracasei subsp. paracasei as adjunct and other autochthonous strains as starters

The use of several autochthonous strains of lactic acid bacteria, including Lactobacillus paracasei subsp. paracasei as adjunct of the starter in the manufacture of Manchego cheese, was evaluated in an attempt to improve the aroma of the industrial Manchego cheese. Volatile composition and odour characteristics were evaluated and compared to those in Manchego cheese manufactured with a commercial starter (CS) culture and with raw milk cheese manufactured without starter. Manchego cheeses manufactured with two autochthonous strains of Lactococcus lactis subsp. lactis displayed a similar volatile profile and odour characteristics to the cheese made with the CS. The use of the strain Lactobacillus paracasei subsp. paracasei CECT 7882 as adjunct of the Lactococcus strains produced cheeses with higher amounts of some free fatty acids and alcohols, acetoin, lactones, phenylacetaldehyde, 2-phenylethanol and linalool, and higher scores of the odour intensity, odour quality, and ewe’s milk odour than the CS cheeses. It resulted in an intensification and improvement of industrial Manchego cheese aroma.     

Influence of microfiltration and adjunct culture on quality of Domiati cheese

The effects of microfiltration and pasteurization processes on proteolysis, lipolysis, and flavor development in Domiati cheese during 2 mo of pickling were studied. Cultures of starter lactic acid bacteria isolated from Egyptian dairy products were evaluated in experimental Domiati cheese for flavor development capabilities. In the first trial, raw skim milk was microfiltered and then the protein:fat ratio was standardized using pasteurized cream. Pasteurized milk with same protein:fat ratio was also used in the second trial. The chemical composition of cheeses seemed to be affected by milk treatment—microfiltration or pasteurization—rather than by the culture types. The moisture content was higher and the pH was lower in pasteurized milk cheeses than in microfiltered milk cheeses at d 1 of manufacture. Chemical composition of experimental cheeses was within the legal limits for Domiati cheese in Egypt. Proteolysis and lipolysis during cheese pickling were lower in microfiltered milk cheeses compared with pasteurized milk cheeses. Highly significant variations in free amino acids, free fatty acids, and sensory evaluation were found among the cultures used in Domiati cheesemaking. The cheese made using adjunct culture containing Lactobacillus delbrueckii ssp. lactis, Lactobacillus paracasei ssp. paracasei, Lactobacillus casei, Lactobacillus plantarum, and Enterococcus faecium received high scores in flavor acceptability. Cheeses made from microfiltered milk received a higher score in body and texture compared with cheeses made from pasteurized milk.     

Volatile compounds, odor, and aroma of La Serena cheese high-pressure treated at two different stages of ripening

La Serena cheeses made from raw Merino ewe's milk were high-pressure (HP) treated at 300 or 400 MPa for 10 min on d 2 or 50 after manufacture. Ripening of HP-treated and control cheeses proceeded until d 60 at 8°C. Volatile compounds were determined throughout ripening, and analysis of related sensory characteristics was carried out on ripe cheeses. High-pressure treatments on d 2 enhanced the formation of branched-chain aldehydes and of 2-alcohols except 2-butanol, but retarded that of n-aldehydes, 2-methyl ketones, dihydroxy-ketones, n-alcohols, unsaturated alcohols, ethyl esters, propyl esters, and branched-chain esters. Differences between HP-treated and control cheeses in the levels of some volatile compounds tended to disappear during ripening. The odor of ripe cheeses was scarcely affected by HP treatments on d 2, but aroma quality and intensity scores were lowered in comparison with control cheese of the same age. On the other hand, HP treatments on d 50 did not influence either the volatile compound profile or the sensory characteristics of 60-d-old cheese.     

The effect of heat treatment and starter culture on colour intensity and sensory properties of Kulek cheese

The effect of the heat treatment on colour intensity and sensory properties of Kulek cheese made from raw milk with (RS) or without starter culture (R) and heated milk with starter culture (HS) was investigated during ripening. Colour L, a and b values of Kulek cheeses were determined for both interior and surface. The values for cheese R were 82.4 and 74.5 for L, ?5.2 and ?5.5 for a, 31.0 and 34.7 for b interior and surface respectively. The equivalents for RS cheese were 82.8 and 75.7 for L, ?4.8 and ?5.0 for a, 31.0 and 34.0 for b. The values for HS cheese were 88.9 and 88.4 for L and ?3.3 and ?3.3 for a, 22.8 and 24.2 for b. L values (lightness) were the highest in cheeses made from heated milk while b and negative a values were the highest in cheeses made from raw milk. Aroma scores of raw and heat‐treated milk cheeses made with starter were not significantly different. The panelists scored cheeses made from raw milk without starter as the best in body and texture.     

Ripened Semihard Cheese Covered with Lard and Dehydrated Rosemary (Rosmarinus officinalis L.) Leaves: Processing,Characterization, and Quality Traits

This study aimed to establish a manufacturing protocol and to characterize semihard cheese covered with lard and rosemary during ripening. After the manufacturing protocol was defined, the cheeses were produced with pasteurized and raw milk from Holstein cows, with and without (control) coating, and then ripened for 60 d. During this period the physicochemical properties, color, proteolysis, texture profile, and sensory acceptance were performed. The early‐ripening cheeses differed from the others in terms of color and moisture content. Multivariate statistical analysis separated chesses in groups differentiated by the effects of heat treatment of milk and ripening period. The ripened cheeses obtained from raw milk were sensorially more preferred. The coating gave the final products higher moisture content and favored color and texture characteristics. Consumer testing showed that the cheese obtained from raw milk and coated with lard and rosemary was the most preferred (acceptance of 82%) due to the specific coating of rosemary (aroma and flavor). This product has potential to add value and to diversify the production of semihard cheeses.     

Microbiological changes throughout ripening of goat cheese made from raw,pasteurized and high-pressure-treated milk

The bacteriological quality during ripening of raw (RA), pasteurized (PA; 72°C, 15 s) and pressure-treated (PR; 500 MPa, 20°C, 15 min) goat milk assessed by enumeration of total bacteria, psychrotrophic bacteria, Enterobacteriaceae, lactobacilli, enterococci, Micrococcaceae and lactococci was evaluated. The high pressure treatment applied was as efficient as pasteurization in reducing the bacterial population of milk. Experimental cheeses were made from RA, PA and PR milks to study the microbial population during ripening. Lactobacilli and lactococci were the predominant microbiota present during ripening in all the cheeses. There were no differences in numbers of starter bacteria during ripening. However, lactobacilli counts for RA milk cheese were significantly higher than for PA and PR cheeses in all the ripening stages studied. Micrococcaceae and enterococci remained at a secondary level, and no differences were observed between cheeses at the end of ripening. On the other hand, the number of Enterobacteriaceae decreased during ripening, but faster in PR milk cheese than in PA and RA milk cheeses. The results of this study suggest that goat cheese made from PR milk had similar microbiological characteristics to PA milk cheeses.     

Factors affecting consumers' preferences for and purchasing decisions regarding pasteurized and raw milk specialty cheeses

Eight hundred ninety consumers at a local food festival were surveyed about their specialty cheese purchasing behavior and asked to taste and rate, through nonforced choice preference, 1 of 4 cheese pairs (Cheddar and Gouda) made from pasteurized and raw milks. The purpose of the survey was to examine consumers’ responses to information on the safety of raw milk cheeses. The associated consumer test provided information about specialty cheese consumers’ preferences and purchasing behavior. Half of the consumers tested were provided with cheese pairs that were identified as being made from unpasteurized and pasteurized milk. The other half evaluated samples that were identified only with random 3-digit codes. Overall, more consumers preferred the raw milk cheeses than the pasteurized milk cheeses. A larger portion of consumers indicated preferences for the raw milk cheese when the cheeses were labeled and thus they knew which samples were made from raw milk. Most of the consumers tested considered the raw milk cheeses to be less safe or did not know if raw milk cheeses were less safe. After being informed that the raw milk cheeses were produced by a process approved by the FDA (i.e., 60-d ripening), most consumers with concerns stated that they believed raw milk cheeses to be safe. When marketing cheese made from raw milk, producers should inform consumers that raw milk cheese is produced by an FDA-approved process.