Protein Quality of Cheddar Cheese Compared with Casein and Fabricated Cheese in the Rat

The protein quality of freeze-dried cheddar cheese, spray-dried cheddar cheese, freeze-dried fabricated cheddar cheese (with casein as the main protein source), and sodium caseinate was evaluated in rats using the protein efficiency ratio (PER) assay (AOAC procedures) in two feeding experiments with casein as the control. Biological evaluation of the products showed that PER values for freeze-dried cheddar cheese were significantly higher than casein (3.7 vs 2.5). Freeze-dried cheddar also had a PER value significantly higher than spray-dried cheddar cheese (3.7 vs 3.0). Freeze-dried fabricated cheddar cheese and sodium caseinate had PER values not significantly different from the casein control.     

Traditional Fermented Foods and Beverages from a Microbiological and Nutritional Perspective: The Colombian Heritage

Fermentation has been used for preserving foods for centuries prior to the invention of pasteurization and sterilization, and every culture has a variety of fermented products as part of its diet. This paper reviews the diversity of fermented foods and beverages from Latin America; these fermented products are produced by traditional methods that exploit mixed cultures of various nonpathogenic microorganisms. Fermented foods covered in this review include maize, cassava, palm sap, sugar cane juice, cocoa, and milk. We explore the history of some Colombian fermented foods and beverages, which are today part of the tradition of some ethnic groups, and evaluate their technology, microbiology, the presence of some nutritional factors, and safety concerns. To the best of our knowledge, this is the 1st systematic review on Colombian fermented beverages and foods, and we believe that it may contribute to valorize these products that are still part of the Latin America tradition.     

Application of Retentate Starter Produced from Ultrafiltered Milk to the Manufacture of Cheddar Cheese

Cheddar cheese was manufactured from whole milk and whole milk retentate using retentate starter made from milk ultrafiltered to 4:1 (vol/vol). One percent retentate starter added to whole milk and 2% starter to 1.7:1 whole milk retentate gave excellent quality cheese. Additionally, a 1% retentate starter added to whole milk gave approximately 3% more cheese. A 2% retentate starter added to 1.7:1 whole milk retentate gave 4% more cheese, reduced cheese making time over that required for control whole milk cheese, and made acid ripening of milk before renneting unnecessary. Starter concentrations above 1% in whole milk and above 2% in whole milk retentates produced some bitterness in the cheese.     

Development of a Mathematical Model for MAP Systems Applied to Nonrespiring Foods

ABSTRACT A mathematical model for gas diffusion processes in MAP systems was built. The model was applied to MAP systems containing CO₂, O₂, and N₂ with nonrespiring foods. The validation study was done with gelatin, and simulation trials were carried out utilizing Hake (Merluccius australis) fillets. Experimental results confirmed the proposed mathematical model and its numerical solution. The prediction errors obtained in the validation study were under 5%; the same was true with the simulation trials whose errors were always lower than 5%. Both the simulation trials and validation study demonstrated that MAP systems reach equilibrium after a short period of time if film permeability is low.     

A Survey on the Some Chemical and Biochemical Properties of Civil Cheese,a Traditional Turkish Cheese

In this article, 15 randomly selected samples of Civil cheese, were purchased from different retail markets in the Erzurum province, Turkey and were investigated for some chemical and biochemical analyses. All cheese samples were analyzed for dry matter, fat, salt, ash, titrable acidity, total nitrogen, soluble nitrogen, ripening index, α_s-and β-casein degradation, γ-casein, and peptides. Dry matter, fat, fat in dry matter, salt, salt in dry matter, ash, and acidity values in samples analyzed were found to be as found between 31.33 and 40.12 g/100 g cheese; 1.00 and 7.00 g/100 g cheese; 2.49 and 18.98 g/100 g cheese; 0.11 and 0.34 g/100 g cheese; 0.27 and 1.04 g/100 g cheese; 1.42 and 5.14 g/100 g cheese and, 0.63 and 2.16%, respectively. TN, WSN/TN, TCA-SN/TN, and PTA-SN/ TN values, expressed as TN%, were found between 3.01 and 5.57 g/100 g cheese, 4.25 and 8.80 g/100 g cheese, 3.23 and 6.12 g/100 g cheese, 1.03, and 5.53 g/100 g cheese in Civil cheese samples analyzed, respectively. SDS-PAGE showed that both α_s-CN and β-CN ratios were not high compared with similar cheeses, and are not completely hydrolyzed in all Civil cheese samples. A broad range of values from chemical and biochemical analysis indicated that Civil cheeses collected from retail markets lacked standardization. Consequently, it was decided that Civil cheese samples do not undergo an excessive proteolysis.     

Development of a Biological Assay to Determine the Allergenic Potential of Foods

Food allergies represent a risk for many people in industrialized countries. Unrecognizable allergenic proteins of foodstuffs may be present as ingredients that are not labeled or as unknown cross-contamination. Such hidden allergens can cause severe reactions in allergics, even at minute quantities, sometimes with fatal outcome. For the verification of the presence of allergenic food constituents, analytical methods such as ELISA and PCR have been developed. However, these tests cannot measure allergenic potential. For this reason, a test system that measures the biological activity of allergens has been developed. It is based on the cellular mechanisms of the type I allergy. Rat basophilic leukemia cells (RBL-2H3) were transfected with the genes of the human high affinity receptor for IgE. The resulting cell line expressed the human receptor α-chain and could bind allergenspecific IgE from allergic subjects, in contrast to the parent cell line. After cross-linking of receptor-bound, allergen-specific human IgE by allergens, the cells released measurable inflammatory mediators. These cells were used for the analysis of a variety of allergen extracts, including extracts prepared from foods containing allergenic hazelnut and peanut. The comparative validation with existing ELISA and PCR for hazelnut and peanut demonstrated similar sensitivity and specificity. The established cell line will be a novel tool in the detection of allergens in complex mixtures, especially to address the issue of their allergenic potential, which cannot be accomplished by classical analytical methods. This will add valuable information about the allergenic potential of food constituents to the risk assessment of foods.     

Development of a Biological Assay to Determine the Allergenic Potential of Foods

Food allergies represent a risk for many people in industrialized countries. Unrecognizable allergenic proteins of foodstuffs may be present as ingredients that are not labeled or as unknown cross-contamination. Such hidden allergens can cause severe reactions in allergics, even at minute quantities, sometimes with fatal outcome. For the verification of the presence of allergenic food constituents, analytical methods such as ELISA and PCR have been developed. However, these tests cannot measure allergenic potential. For this reason, a test system that measures the biological activity of allergens has been developed. It is based on the cellular mechanisms of the type I allergy. Rat basophilic leukemia cells (RBL-2H3) were transfected with the genes of the human high affinity receptor for IgE. The resulting cell line expressed the human receptor α-chain and could bind allergenspecific IgE from allergic subjects, in contrast to the parent cell line. After cross-linking of receptor-bound, allergen-specific human IgE by allergens, the cells released measurable inflammatory mediators. These cells were used for the analysis of a variety of allergen extracts, including extracts prepared from foods containing allergenic hazelnut and peanut. The comparative validation with existing ELISA and PCR for hazelnut and peanut demonstrated similar sensitivity and specificity. The established cell line will be a novel tool in the detection of allergens in complex mixtures, especially to address the issue of their allergenic potential, which cannot be accomplished by classical analytical methods. This will add valuable information about the allergenic potential of food constituents to the risk assessment of foods.

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Zusammenfassung. Allergene Lebensmittelbestandteile stellen für viele Nahrungsmittelallergiker in industrialisierten L?ndern ein reales Gesundheitsrisiko dar, wenn sie als nicht deklarierte Zutaten oder unerkannte Kontaminationen in Lebensmitteln enthalten sind. Diese so genannten versteckten Allergene k?nnen, teilweise in geringsten Mengen, schwere Reaktion bei sensibilisierten Personen auszul?sen, manchmal auch mit t?dlichem Ausgang. Zum Nachweis allergener Lebensmittelbestandteile wurden bereits verschiedene analytische Methoden, wie z. B. ELISA- und PCR-Verfahren, entwickelt. Allerdings sind diese Methoden nicht in der Lage, das allergene Potenzial solcher Bestandteile zu erfassen. Um jedoch die biologische Aktivit?t von Allergenen messen zu k?nnen wurde ein Testsystem entwickelt, das auf dem Mechanismus der Typ-I Allergie basiert. Dazu wurden basophile Leuk?miezellen der Ratte mit den Genen des humanen hochaffinen Rezeptors für IgE transfiziert. Die daraus resultierende Zelllinie exprimiert einen chim?ren Rezeptor (mit der IgE-bindenden humanen α-Kette) stabil auf ihrer Oberfl?che und ist somit in der Lage, auch allergenspezifisches IgE aus Allergikerseren zu binden, was mit der Ausgangszelllinie nicht m?glich ist. Die Vernetzung des rezeptorgebundenen IgEs durch das Allergen führt in der Folge zur Freisetzung entzündungsausl?sender Mediatoren, die im Zellkulturüberstand gemessen werden k?nnen. Diese transfizierte Zelllinie wurde zur Analyse einer Vielzahl von Allergenextrakten eingesetzt, darunter auch Extrakte von Lebensmitteln, die Haselnuss- oder Erdnussallergene enthielten. Der Vergleich des biologischen Testsystems mit den ELISA- und PCR-Verfahren für Hasel- und Erdnuss ergab eine ?hnliche Sensitivit?t und Spezifit?t. Die etablierte Zelllinie ist ein neues, wertvolles Hilfsmittel für den Nachweis von Allergenen in komplexen, zusammengesetzten Lebensmitteln und im Besonderen zur Erfassung des allergenen Potenzials solcher Nahrungsmittelbestandteile. Somit kann dieses neue Nachweisverfahren helfen, zus?tzliche wichtige Informationen für die Risikobewertung von Lebensmitteln zu gewinnen.

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Silter Cheese,a Traditional Italian Dairy Product: A Source of Feasible Probiotic Strains

Silter cheese is a traditional hard cheese, produced in Valcamonica, Brescia, Italy. A total of 426 lactic strains isolated from Silter were analyzed to determine their probiotic characteristics. 274 out of 426 strains were found to produce bacteriocins against at least one of eight different pathogens (Salmonella enterica, Listeria monocytogenes, Salmonella derby, Salmonella thyphimurium, Salmonella napoli, Staphylococcus aureus, E. coli O157:H7, Salmonella enteritidis). In addition, 211 of 274 bactericin-producer strains adhered to Caco-2 cells and were characterized by RiboPrinter, revealing predominance of Enterococcus faecalis (26%) and Enterococcus durans-faecium (22%). These findings suggest that Silter may qualify as an important source of feasible probiotic strains.     

感官品评方法在缩短再制奶酪研发周期中的应用

在研发过程中,不断调节产品配方靠近目标产品特点时需要较长的研发周期。通过感官品评方法中的描述型测试,明确了两个样品与目标产品之间的差异及差异程度,从而使研发人员明确配方改进方向,起到了缩短研发周期的作用。     

Development of a Continuous Process for the Production of Ricotta Cheese

A process was developed for the continuous production of Ricotta cheese. The process consists of multistep heating to 92°C, whey protein denaturation in a 10-min holding tube, acid injection to induce coagulation (2.5% citric acid), curd formation in a clear plastic holding tube (10 min), followed by separation of curd from deproteinated whey on a nylon conveyer belt. The process resulted in 98.1% removal of the recoverable solids. Recoveries of protein and fat were 99.5 and 99.6%, respectively.Cheese, prepared from a blend of 80% sweet whey and 20% whole milk, contained 33.5% total solids, 16.30% protein, and 11.6% milk fat. Italian Ricotta, prepared from whey ultrafiltered 4.5 to 1, contained 19.8% total solids, 15.9% protein, and 2.4% fat. The pH of Ricotta prepared from the whey and milk blend (80:20) ranged from 5.6 to 5.8, whereas pH of Ricotta prepared from only ultrafiltered whey (4.5 to 1) was 5.7 to 5.9.The process has advantages over other conventional mechanized cheese processes in terms of reduced capital and operating costs. The process is suitable for cheese factories that may wish to produce Ricotta as a protein base for other food products, such as cream cheese, processed cheese, snack food dips, and quiches.     

Long Term Use of a Cheddar Starter and Development of Phages with Homology to its Bacteria

A mixed, homofermentative, mesophilic starter was used for more than 11 years as the only starter for production of Cheddar cheese at a Danish cheese factory. The activity of the starter at the factory was carefully recorded, and whey samples were regularly tested for bacteriophages. During the years bacteriophages, homologous to an increasing number of the strains of the starter culture, gradually evolved. After 4 years bacteriophages, homologous to more than 50%—and after 6 years to more than 90%—of 62 bacterial isolates from the starter, had appeared. For most of the strains the virulence of their phages was low at first and thereafter increased over several years. It was, however, only after more than 11 years that the cheese factory first began to observe cases of reduced activity of the bulk starter; presumably because the virulence of the bacteriophages had developed to such a degree that very low levels of contamination of the milk for bulk starter could impair the subsequent activity of the bulk starter in the curd.     

Moderately High Hydrostatic Pressure Processing to Reduce Production Costs of Shredded Cheese: Microstructure, Texture, and Sensory Properties of Shredded Milled Curd Cheddar

ABSTRACT: Short and moderate hydrostatic pressure (MHP) treatments accelerated the shredability of Cheddar cheese. Both MHP (345 MPa for 3 and 7 min) and higher pressure (483 MPa for 3 and 7 min) treatments applied to 1-d milled curd Cheddar cheese induced immediately a microstructure resembling that of ripened cheese. Unripened pressure-treated Cheddar cheese yielded shreds with visual and tactile sensory properties similar to those obtained from untreated 27-d-old Cheddar cheese. All pressure treatments reduced the presence of crumbles, increased mean shred particle length, improved length uniformity, and enhanced surface smoothness. Sensory evaluations showed that shredded samples of 1-d MHP-treated cheese and 27-d untreated cheese had similar sensory attributes. Pressure treatments did not affect mechanical properties of ripened cheese and milk protein proteolysis was not inhibited. These results showed that MHP would allow processors to shred milled curd Cheddar cheese immediately after block cooling with expected refrigerated storage savings of more than $30 US/1000 kg cheese and could simplify the handling of cheese for shredding. Shreds from unripened milled curd Cheddar cheese can thus be produced with high visual acceptability and improved tactile handling using moderate levels of hydrostatic pressure.     

Selection of Dominant NSLAB from a Mature Traditional Cheese According to their Technological Properties and in vitro Intestinal Challenges

Abstract: Isolates (47) of lactobacilli from 5 different productions of Melichloro cheese were examined for potential use as adjunct cultures. The sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) of whole‐cell proteins classified 29 isolates as L. paraplantarum and 18 as L. paracasei subsp. paracasei. Randomly amplified polymorphic DNA‐polymerase chain reaction (RAPD‐PCR) analysis differentiated the L. paraplantarum and L. paracasei subsp. paracasei isolates at strain level and both, RAPD analysis and whole‐cell protein profiling provided useful information about the diversity of nonstarter lactic acid bacteria (NSLAB) in the different cheese productions. The isolates were slow acidifiers and about 70% of them degraded, preferentially α_s‐casein. The amounts of amino acids accumulated in the milk increased with the incubation time. A similar enzyme profile was exhibited by strains of both species, except for α‐mannosidase and α‐fucosidase, which were not detected in the L. paracasei subsp. paracasei strains. All strains grew in the presence of bile at 0.3% and the majority was able to withstand pH 2.5 and pancreatin at 0.1%. Moreover, all strains reduced cholesterol in vitro, with higher removal ability recorded for strains of L. paraplantarum. A narrow spectrum of antibacterial activity was recorded for 88% of the strains. Selected isolates with appropriate technological and interesting in vitro intestinal challenges could be used as adjuncts and deserve further studies. Practical Application: Strains selected by this study could be used as adjuncts to make the Melichloro cheese. Their contribution to cheese flavor is then going to be studied to select the most appropriate. Of course these strains have to be also studied for their probiotic potential, to say that we have a probiotic food.     

以奶酪生产为契机引领新疆奶业发展

从新疆开发奶酪市场的优劣势分析、奶酪的专利分析方面,阐述了新疆奶业的出路--发展奶酪生产。     

Development and application of image analysis to quantify calcium lactate crystals on the surface of smoked Cheddar cheese

Calcium lactate crystals that form white specks or haze on the surface of cheese constitute a significant quality problem for producers of Cheddar cheese. Subjective methods to evaluate crystal coverage of cheese surfaces have been reported previously, but objective methods are currently lacking. The objectives of this work were to develop and evaluate an objective method to measure the area occupied by calcium lactate crystals on surfaces of naturally smoked Cheddar cheese samples using digital photography and image analysis. Coefficients of variation ranged from 1.29 to 4.68% for 5 replicate analyses of 3 different cheese surfaces that ranged from ∼2 to 49% of total surface area occupied by crystals. Thus, results showed a high degree of repeatability for the 3 cheese surfaces, which ranged from very slight and geometrically simple to very heavy and geometrically complex crystal coverage. The method underestimated total area occupied by crystals on the 3 surfaces by 0.24 to 4.83% unless the fainter crystal regions that went undetected during initial thresholding were manually segmented and quantified. The wet weight of crystal substance collected per unit of surface area from 20 different cheese samples increased exponentially as the percentage of total surface area occupied by crystals increased. These data were consistent with subjective observations that crystal regions appeared to grow vertically as well as horizontally as they expanded to occupy greater surface area. Image analysis was well suited for evaluating changes in crystal coverage during cheese aging because measurements were made nondestructively and with minimal disruption to the cheese. The area occupied by crystals on 6 different surfaces from 3 different cheese samples increased linearly (R² = 0.94 to 0.99) during storage at 4°C for up to 33 wk. However, the rates of increase differed significantly among the 3 cheese samples. Image analysis may serve as a useful tool to quantitatively evaluate the effects of factors such as cheese composition, packaging conditions and storage temperature on rate of crystal growth and time of crystal appearance during storage.