Microbiological,physicochemical and sensory characteristics of Cameros cheese packaged under modified atmospheres

This study evaluated the shelf-life quality of Cameros cheeses packaged under modified atmospheres. Five different modified atmosphere conditions were studied (carbon dioxide/nitrogen mixtures and vacuum). Control cheeses were packaged in air. The product stored at 3–4°C was evaluated periodically to investigate its sensory quality, microbiological condition and physicochemical characteristics. Weight loss and pH evolution were similar in vacuum and air packaging. Cheeses packaged in 100% CO₂showed the greatest weight losses and lower pH values. CO₂reduced proteolysis and lipolysis during storage in all conditions studied. Fat acidity and NPN/TN values were slightly higher in vacuum than in CO₂, but lower than in air. Modified atmosphere packaging presented an extended shelf life. Those containing CO₂reduced the growth rate of mesophiles, psychrotrophs, Enterobacteriaceae and coliforms, which was lower when the CO₂concentration increased. The lowest microbial counts were at 100% CO₂while vacuum conditions presented microbial counts only slightly lower than the controls. Salmonella spp.,Staphylococcus aureus and Listeria spp. were not found in any of the samples. Faecal coliforms, moulds and yeasts were not detected under CO₂atmospheres or in vacuum. After 7 days of storage, the sensory characteristics of the control cheeses were unacceptable in all the parameters studied. However, the overall score for cheeses stored in 40% and 50% CO₂did not change substantially, retaining a reasonable acceptability until the end of the storage period. The 100% CO₂atmosphere had a very negative effect on sensory quality. With regard to Cameros cheese, packaging in 50%CO₂/50%N₂and 40%CO₂/60%N₂are the most effective for extending shelf life and retaining good sensory characteristics.     

The growth of Listeria monocytogenes in fresh goat cheese (Cameros cheese) packaged under modified atmospheres

The effect of modified atmosphere packaging (MAP) on the growth of Listeria monocytogenes in inoculated and non-inoculated Cameros cheese was evaluated. Three different modified atmosphere conditions were studied (20%CO₂/80%N₂, 40%CO₂/60%N₂ and 100%CO₂). Control cheeses were packaged in air. The product was stored at 4°C and evaluated periodically to investigate its microbiological quality.MAP presented an extended shelf-life. Those containing CO₂ reduced the growth rate of mesophiles, psychrotrophs and anaerobes, which was lower when the CO₂ concentration increased. A concentration of 100% CO₂ showed the lowest microbial counts. L. monocytogenes growth was lower when the CO₂ concentration increased. However, after 28 days the L. monocytogenes population was 1·3 log units lower in inoculated cheeses packaged at 100% CO₂ than in those packaged in air. Listeria monocytogenes can grow in atmospheres containing 20, 40 and 100% CO₂. L. monocytogenes were not found in any of the non-inoculated samples. It was concluded that MAP was not a suitable means to prevent the growth of L. monocytogenes in Cameros cheese.     

Effect of Modified Atmosphere Pakaging on the Shelf-life of Common Carp (Cyprinus carpio) Steaks

The effect of modified atmosphere packaging (MAP 1: 40%CO₂+60%N₂ and MAP 2: 100%CO₂) on the shelf-life of carp steaks was studied. Carp steaks were stored at +3±0.5˚C and on days 1, 3, 6, 9, 13 and 15, microbiological, chemical and sensory testing was performed. Based primarily on odour scores it was observed that carp steaks packaged in MAP1 remained acceptable up to 13 days of storage, while carp steaks packaged in MAP2 remained unchanged until the end of the study. By using MAP, especially 100% CO₂, products shelf-life can be significantly prolonged.     

Quality parameters and shelf-life of smoked Dalmatian dry-cured ham packed in bio-based and plastic bilayer pouches

Traditional Dalmatian dry-cured ham (prosciutto) was packaged under modified atmosphere, MAP (30%CO₂/70%N₂) and vacuum, in commercial polyamide/polyethylene (PA/PE) and biodegradable poly(lactic acid) (PLA) material. Samples were stored at 4 °C for 180 days and the effect of packaging materials and methods on various quality parameters was studied. The least changes were observed for PA/PE for both packaging methods. The pH, moisture content, colour parameters, TBARS and DNPH values of dry-cured ham packed in PLA were significantly affected already after 1 month in MAP and after 3 months in vacuum packaging. Similar changes in the above parameters were also observed in the control sample (packed in air-PA/PE) while vacuum-PA/PE and MAP-PA/PE showed significantly better results. The instrumental analyses agreed with the sensory panel results where appearance, taste, texture and overall acceptability of PLA samples decreased significantly already after 2 months of storage. For both, MAP-PA/PE and vacuum-PA/PE samples, the shelf-life was estimated to be 5 months.     

Comparative study of flavor, texture, and sensory in cream cheese and cholesterol-removed cream cheese

This study was performed to compare flavor, texture, and sensory profiles of cream cheese and cholesterolremoved cream cheese made from whole milk and cream. The cholesterol was removed by crosslinked β-cyclodextrin and the cheeses were stored at 7°C for 4 week. To quantify the flavor compounds, the cheeses (0, 1, 2, 3, and 4 week) were extracted by solid-phase microextraction, analyzed by GC-MS and quantified by GC-flame ionization detector (FID). Tentatively identified flavor compounds were 11 acids, 2 ketones, 1 amine, 1 alcohol, 2 lactone, and 1 alkene. In texture profile analysis such as hardness, cohesiveness, adhesiveness, and sensory analysis such as appearance, flavor, taste, and texture properties were not significantly different (p>0.05) between two cheeses. On the basis of our results, it is concluded that no adverse changes was shown in the cholesterol-removed cream cheese in flavor, texture, and sensory characteristics during 4-week storage.     

Probiotic cheese production using Lactobacillus casei cells immobilized on fruit pieces

Lactobacillus casei cells were immobilized on fruit (apple and pear) pieces and the immobilized biocatalysts were used separately as adjuncts in probiotic cheese making. In parallel, cheese with free L. casei cells and cheese only from renneted milk were prepared. The produced cheeses were ripened at 4 to 6°C and the effect of salting and ripening time on lactose, lactic acid, ethanol concentration, pH, and lactic acid bacteria viable counts were investigated. Fat, protein, and moisture contents were in the range of usual levels of commercial cheeses. Reactivation in whey of L. casei cells immobilized on fruit pieces after 7 mo of ripening showed a higher rate of pH decrease and lower final pH value compared with reactivation of samples withdrawn from the remaining mass of the cheese without fruit pieces, from cheese with free L. casei, and rennet cheese. Preliminary sensory evaluation revealed the fruity taste of the cheeses containing immobilized L. casei cells on fruit pieces. Commercial Feta cheese was characterized by a more sour taste, whereas no significant differences concerning cheese flavor were reported by the panel between cheese containing free L. casei and rennet cheese. Salted cheeses scored similar values to commercial Feta cheese, whereas unsalted cheese scores were significantly lower, but still acceptable to the sensory panelists.     

Effect of Vacuum and Modified Atmosphere on Enterobacteriaceae Count Determined in Rainbow Trout (Oncorhynchus Mykiss) and Carp (Cyprinus Carpio) Steaks

The aim of our research was to determine the presence and examine the change in total number of Enterobacteriaceae in trout and carp cuts packed in vacuum and modified atmosphere. To conduct the study, three sample groups of cleaned trout and carp cuts were formed. The first two groups were packaged in modified atmospheres with different gas ratios: 60%CO₂+40%N₂ (I group) and 40%CO₂+60%N₂ (II group), whereas the third group of fish cuts were vacuum packaged. Our results suggest that modified atmosphere packaging of fresh fish with an appropriate percentage of CO₂ might reduce the risk of poisoning people with Enterobacteriaceae.     

Shelf life of Turkish whey cheese (Lor) under modified atmosphere packaging

In this study, the shelf life of Lor cheese stored under different atmosphere compositions was assessed and compared. Lor cheeses were held in four different atmospheres containing: vacuum packaging (VP), 40% CO₂/60% N₂, 60% CO₂/40% N₂ and 70% CO₂/30% N₂ (modified atmosphere packaging). Control cheeses were stored in air. All cheese samples were kept in the refrigerator at 4°C for 45 days and investigated for physicochemical, microbiological and sensory properties. The acidity index value was significantly higher ( P  < 0.05) in the control and vacuum packaged samples than in those stored for the same period under CO₂. Microbiological results showed that modified atmosphere packaging delayed microbial growth compared with air and VP samples. Of the three modified atmospheres, gas mixtures 60% and 70% CO₂ were the most effective for inhibition of growth of micro-organisms. Sensory evaluation (odour and taste) results showed that Lor cheese packaged under modified atmosphere packaging (60% CO₂/40% N₂ and 70% CO₂/30% N₂ ) retained good characteristics for 45 days of storage, while vacuum and control samples were sensorily unacceptable after 10 days of storage.     

Assessing the yield,microstructure, and texture properties of miniature Chihuahua-type cheese manufactured with a phospholipase A1 and exopolysaccharide-producing bacteria

Chihuahua cheese or Mennonite cheese is one of the most popular and consumed cheeses in Mexico and by the Hispanic community in the United States. According to local producers the yield of Chihuahua cheese ranges from 9 to 9.5 kg of cheese from 100 kg of milk. Cheese yield is a crucial determinant of profitability in cheese-manufacturing plants; therefore, different methods have been developed to increase it. In this work, a miniature Chihuahua-type cheese model was used to assess the effect of a phospholipase A₁ (PL-A₁) and exopolysaccharide (EPS)-producing bacteria (separately and in combination) on the yield, microstructure, and texture of cheese. Four different cheeses were manufactured: cheese made with PL-A₁, cheese made with EPS-producing bacteria, cheese with both PL-A₁ and EPS-producing bacteria, and a cheese control without PL-A₁ or EPS-producing bacteria. The compositional analysis of cheese was carried out using methods of AOAC International (Washington, DC). The actual yield and moisture-adjusted yield were calculated for all cheese treatments. Texture profile analyses of cheeses were performed using a texture analyzer. Micrographs were obtained by electron scanning microscopy. Fifty panelists carried out sensorial analysis using ranking tests. Incorporation of EPS-producing bacteria in the manufacture of cheese increased the moisture content and water activity. In contrast, the addition of PL-A₁ did not increase fat retention or cheese yield. The use of EPS alone improved the cheese yield by increasing water and fat retention, but also caused a negative effect on the texture and flavor of Chihuahua cheese. The use of EPS-producing bacteria in combination with PL-A₁ improved the cheese yield and increased the moisture and fat content. The cheeses with the best flavor and texture were those manufactured with PL-A₁ and the cheeses manufactured with the combination of PL-A1 and EPS-producing culture.     

Preservation of precut white cheese by modified atmosphere packaging

Effects of modified atmosphere packaging (MAP) on storage stability and quality of precut fresh and aged white cheese were investigated. Fresh or aged white cheese was cut into small cubes and packaged in five different atmospheres [0% O₂ + 0% CO₂ + 100% N₂ (MAP1), 10% O₂ + 0% CO₂ + 90% N₂ (MAP2), 0% O₂ + 75% CO₂ + 25% N₂ (MAP3), 10% O₂ + 75% CO₂ + 15% N₂ (MAP4) and aerobic (air)]. Control samples were packaged in brine and vacuum for fresh and aged white cheese, respectively. Changes in gas composition, total plate count, lactococci, lactobacilli, yeast and mould counts, proteolysis, lipolysis, pH, colour, texture and sensory properties were investigated during refrigerated storage. The best packaging treatment for the fresh cheese was MAP3, as it inhibited mould growth and protected the hardness. MAP2 can be recommended for the packaging of the aged cheese, as it decreased lipolysis.     

Shelf-life extension and quality attributes of the whey cheese “Myzithra Kalathaki” using modified atmosphere packaging

The present work evaluated the effect of modified atmosphere packaging (MAP) on quality characteristics and shelf-life extension of the whey cheese “Myzithra Kalathaki” using microbiological, chemical and sensory analyses. Myzithra cheese was packaged in four different atmospheres: vacuum, 20% CO₂/80% N₂ (M₁), 40% CO₂/60% N₂ (M₂) and 60% CO₂/40% N₂ (M₃); identical cheese samples were packaged in air, taken as controls. All cheese samples were kept under refrigeration (4±0.5 °C) for 45 days. Of the four atmospheres, the M₂ and M₃ gas mixtures were the most effective for inhibiting growth of aerobic microflora and psychrotrophs in cheese samples until days 40 and 33 of refrigerated storage, respectively. Lactic acid bacteria (LAB) were part of the cheese microflora becoming dominant toward the end of the storage period regardless of packaging conditions. Enterobacteriaeceae were also part of the cheese microflora being effectively inhibited after day 35 of storage. Molds and yeasts were also totally inhibited by MAP (M₂ and M₃) gas mixtures throughout the entire storage period. Of the chemical quality indices determined, lipid oxidation varied below 0.005 absorbance at 532 nm for all treatments, except control samples for which absorbance values of 0.02 were recorded after 35 days of storage. Lipolysis did not vary significantly with type of packaging treatment while proteolysis values showed and increasing trend up to day 25 of storage and then decreased toward the end of the storage period. Sensory evaluation (odour and taste) showed that Myzithra cheese packaged under MAP (M₂ and M₃) retained good sensory characteristics for 30 days of storage while control samples were sensorily unacceptable after 10-12 days of storage.     

Shelf-life of Domiati cheese under modified atmosphere packaging

The present study describes the effects of modified atmosphere packaging (MAP) on shelf-life extension, chemical, microbiological, and sensory properties of Domiati cheese. Five different MAP were studied [10% CO₂/90% N₂ (G1), 15% CO₂/85% N₂ (G2), 25% CO₂/75% N₂ (G3), 100% CO₂ (G4), and 100% N₂ (G5)]. Control samples were packaged in air (CA) and under vacuum. In both groups of cheeses, chemical analysis was significantly affected by MAP during cold storage. Ripening indexes were significantly affected by MAP during cold storage. Microbiological data showed that G4, followed by G5, were the most effective groups inhibiting the growth of total aerobic mesophilic and psychrotrophic bacteria, and yeasts and molds until the end of storage. Sensory evaluation was significantly affected by MAP and storage period, at 45 d CA cheese samples were judged as unacceptable. The best sensory properties were obtained in G5, G4, and G3 treatments, and recorded a relatively higher sensory evaluation scores. The best shelf-life extension was obtained in G5, G4, and G3 treatments.     

Extending the shelf life of fresh ewe’s cheese by modified atmosphere packaging

This study evaluated the effect of modified atmosphere packaging (MAP) in extending the shelf life of a fresh ewe’s cheese stored at 4 °C for 21 days. Three batches were prepared with 20, 30 or 50% CO₂ with N₂ as filler gas. MAP controlled well the microbial growth, and the best result was obtained with 50% CO₂. Pathogens were not detected in any sample. Softening of cheese was best reduced by 30% or 50% CO₂. The sensory characteristics of the cheeses markedly decreased during storage. Only the sample stored with 50% CO₂ obtained an overall score above the acceptability at 14 days.     

Evaluation of PLA nanocomposite films on physicochemical and microbiological properties of refrigerated cottage cheese

A novel antimicrobial packaging system was prepared by incorporating TiO₂ or Ag nanoparticles into poly(lactic acid) (PLA) matrix. The effect of PLA, PLA/TiO₂, and PLA/TiO₂ + Ag film on the physicochemical and microbiological properties of Yunnan cottage cheese stored at 5 ± 1 °C for 25 days was investigated. The low density polyethylene (LDPE) film was used as the control. The weight loss, pH value, lactic acid bacteria count (LAB), texture, sensory quality, and antimicrobial activity were determined. Cheeses packed by PLA/TiO₂ and PLA/TiO₂+Ag film provided better retention in pH value, LAB, sensory quality, and antimicrobial activity compared with those packed by PLA and LDPE film. Migration of Ti and Ag nanoparticles was lower than the limit of 10 mg/kg as defined by EFSA for food contact materials. The results indicated that the incorporation of TiO₂ or Ag nanoparticles into PLA matrix could maintain cheese quality and prolong its shelf life to 25 days.

Practical applications

Yunnan cottage cheese is one of the most popular cheeses in China. However, the shelf life of unpacked Yunnan cottage cheese is only 5–7 days under refrigerated condition. PLA film incorporated with antimicrobial TiO₂ or Ag nanoparticles has great potential to prolong cheese shelf life. The novel packaging material may be an effective alternative for cheese preservation.     

Biochemical patterns in ovine cheese: Influence of probiotic strains

This study was undertaken to evaluate the effect of lamb rennet paste containing probiotic strains on proteolysis, lipolysis, and glycolysis of ovine cheese manufactured with starter cultures. Cheeses included control cheese made with rennet paste, cheese made with rennet paste containing Lactobacillus acidophilus culture (LA-5), and cheese made with rennet paste containing a mix of Bifidobacterium lactis (BB-12) and Bifidobacterium longum (BB-46). Cheeses were sampled at 1, 7, 15, and 30 d of ripening. Starter cultures coupled with probiotics strains contained in rennet paste affected the acidification and coagulation phases leading to the lowest pH in curd and cheese containing probiotics during ripening. As consequence, maturing cheese profiles were different among cheese treatments. Cheeses produced using rennet paste containing probiotics displayed higher percentages of α_S1-I-casein fraction than traditional cheese up to 15 d of ripening. This result could be an outcome of the greater hydrolysis of α-casein fraction, attributed to higher activity of the residual chymosin. Further evidence for this trend is available in chromatograms of water-soluble nitrogen fractions, which indicated a more complex profile in cheeses made using lamb paste containing probiotics versus traditional cheese. Differences can be observed for the peaks eluted in the highly hydrophobic zone being higher in cheeses containing probiotics. The proteolytic activity of probiotic bacteria led to increased accumulation of free amino acids. Their concentrations in cheese made with rennet paste containing Lb. acidophilus culture and cheese made with rennet paste containing a mix of B. lactis and B. longum were approximately 2.5 and 3.0 times higher, respectively, than in traditional cheese. Principal component analysis showed a more intense lipolysis in terms of both free fatty acids and conjugated linoleic acid content in probiotic cheeses; in particular, the lipolytic pattern of cheeses containing Lb. acidophilus is distinguished from the other cheeses on the basis of highest content of health-promoting molecules. The metabolic activity of the cheese microflora was also monitored by measuring acetic, lactic, and citric acids during cheese ripening. Cheese acceptability was expressed for color, smell, taste, and texture perceived during cheese consumption. Use of probiotics in trial cheeses did not adversely affect preference or acceptability; in fact, panelists scored probiotic cheeses higher in preference over traditional cheese, albeit not significantly.     

Fatty acid and sensory profiles of Caciocavallo cheese as affected by management system

The effect of season of the year associated with changes in feeding and management system (pasture-based vs. confinement) on milk and cheese fatty acid profile and on sensory properties of Caciocavallo cheese was evaluated on 3 mountain dairy farms. Each farm used a pasture-based feeding system from April to June and from September to October (PS), and a confinement system for the rest of the year (CS). As a consequence of grazing, PS milk showed higher percentages of C18:3, cis-9,trans-11 conjugated linoleic acid, and trans-11 C18:1, and a reduced percentage of C16:0. The fatty acid profile of cheese largely reflected that of the corresponding raw milk from which cheese was made. This led to a significant decrease of atherogenic index in cheeses produced from cows on pasture. Based on sensory analysis, cheese from animals kept on pasture was more yellow and had a lower intensity of butter and smoked odors than did CS cheese. In addition, grazing induced a lower intensity of bitter and a higher intensity of spicy flavors compared with cheese from CS animals. In regard to texture, pasture feeding resulted in higher intensity of friability and graininess. All cheeses performed well in consumer tests; the panel found all samples more than acceptable for overall liking, and for liking according to appearance, taste/flavor, and texture. Overall liking of Caciocavallo cheese, as assessed by slope analysis, was affected primarily by taste/flavor (raw slope k = 0.88) and texture (k = 0.97), whereas appearance had a lesser effect (k = 0.72). The acidic and sensory profiles of cheese were well discriminated, with healthier cheeses produced by grazing cows. Therefore, wider use of pasture should be promoted to accentuate this favorable feature. Based on the specific nutritional and sensory characteristics of mountain Caciocavallo cheese, particularly that obtained from grazing animals, efforts should be made to indicate the quality of this cheese to the consumer and improve product recognition.