Comparison of basic nutrients, mineral and heavy metal contents of herby dairy products

The aim of this study was to determine basic nutrients, some minerals and heavy metal contents of herby cheese, cacik and lor. Herby cheese is a cheese made from cow and/or sheep milk mixed with some herb. Herby cacik is a dairy product manufactured from light yoghurt (non-fat), ayran (liquid yoghurt) and/or a small amount of cheese whey. Herby lor cheese is a product traditionally made in Turkey, produced from cheese whey and occasionally some whole milk added. These dairy products are mixed with wild herb species (Allium sp., Chaerophyllum macropodum, Antriscus nemorosa, Ferula sp., Prangos sp., Silene vulgaris, Tymus sp. and Mentha sp.). In this study, herby cacik, cheese and lor samples were analysed for some physicochemical, mineral and heavy metal contents. The dry matter, protein, fat, salt and ash contents among herby dairy products were found significantly different (P < 0.05). There were significant differences in Ca, P, Na, Mg, Fe, Cu and Mn content of herby dairy products (P < 0.05). Zn, Co, Cr, Ni and Cd contents of analysed samples were not significantly different (P > 0.05).     

The effect of mendi (Chaerophyllum sp.) on ripening of vacuum-packed herby cheese

The composition, biochemical and sensory parameters of control cheese (without herbs) and four herby cheeses at 0.5, 1, 2 and 3% herb levels (mendi, Chaerophyllum sp.) ripened at 4 ± 1°C for 90 days were compared. As herb levels increased from 0.5 to 3%, dry matter and pH value decreased significantly. However, dry matter of all cheeses showed similar changes during ripening. The salt content of samples changed from 3.44 to 5.47% during ripening. There was a tendency toward slightly higher titratable acidity in cheeses with more added herbs. Ripening index, trichloroacetic acid-soluble nitrogen/total nitrogen, phosphotungstic acid-soluble nitrogen/total nitrogen, and lipolysis values of the cheese samples were affected by adding herbs and by ripening time. The most acceptable sensory score was obtained with 1% added herbs.     

THE CONTRIBUTION OF HERBS TO THE ACCUMULATION OF HISTAMINE IN "OTLU" CHEESE

The aim of this study was to determine the effect of herbs and the use of raw milk on histamine accumulation in “Otlu” (Herby) cheese during ripening. Cow's milk was used for the cheese production. The milk was divided into two main groups: one was used raw and the other was pasteurized at 65C for 30 min. Each group was further divided into two subparts, one of which was used as control (without herbs), while 2% (w/v) of the herbs were added into the other to produce Herby cheese. All cheeses were ripened at 7C for 90 days. The cheese samples were analyzed in terms of histamine content, titratable acidity, dry matter, salt and degree of ripening on days 5, 30, 60 and 90. Total mesophilic aerobic bacteria (MAB) were also counted during ripening. The use of raw milk and the addition of herb both increased histamine formation in Otlu cheeses (P < 0.05). Moreover, higher water‐soluble nitrogen values, as degree of ripening, were obtained from both raw milk and herb‐added cheeses. The number of MAB was higher in raw cheeses (P < 0.05) and also herb‐added cheeses. The study suggests that the addition of herbs may facilitate histamine formation in Herby cheese.     

Characterization and Comparison of Free Fatty Acid Profiles of Eleven Varieties of Turkish Cheeses

Free fatty acids profiles of 11 different cheese varieties sold in Turkey were determined to assess the development of lipolysis. Results obtained showed that the concentrations of short chain fatty acids (C₄ and C₆ free fatty acids) were close in all cheeses (P > 0.05), except for Canak cheese. However, significant differences were noted among the samples for other free fatty acids including C₈ to C_18:2 (P < 0.05). Palmitic (C₁₆) and oleic (C_18:1) acids were the most abundant free fatty acids in all cheese samples. Principal component analysis was applied to simplify interpretation of the data and distinguish the variety of the cheeses on the plot. Canak cheese gave a dramatically different free fatty acid profile from the other cheeses, probably because of the fact that ripening of this variety is achieved in the earthenware pots for about 1 year. Van Otlu (ripened with special herbs) and Civil (ripened by spontaneously molding on its surface) cheeses differed from the others by ANOVA and principal component analysis techniques. In conclusion, the degree of lipolysis in the cheeses could be classified into extreme (Canak), high (Civil, Divle Tulum, Mihalic, and Van Otlu), mild (Ezine, Orgu, and Urfa), and low (Dil, Hellim, and Malatya) based on their FFA profiles.     

THE FORMATION OF HISTAMINE IN HERBY CHEESE DURING RIPENING

The purpose of this study is to observe the formation of histamine throughout the period of ripening in herby cheese. Herby cheese samples were made from raw milk and buried in soil where they mature in 3 months. Samples were taken on the first, seventh, 15th, 30th, 60th and 90th days of ripening. The moistness, content pH, salt and (total aerobic mesophile bacteria, lactic acid bacteria, coliform bacteria and yeasts and mold) changes were observed. The concentration of histamine are 2.19 mg/100 g on the first day of ripening. It gradually increased and reached 4.62 mg/100 g on the 90th day. Consequently, the histamine that was observed in herby cheese during the ripening appears to be not important for public health.     

The effect of Allium sp. on the extension of lipolysis and proteolysis in Van herby cheese during maturation

The aim of this study was to determine the effect of herb (Allium sp.) on biochemical changes of herby cheese produced in Turkey. Raw cows' milk was used for cheese manufacture. Five groups of cheeses, containing 0 (as control), 0.5, 1, 2, and 3% herb, were produced and coded as K, A, B, C, and D respectively. All cheese groups were ripened at 8 degrees C for 90 days. Samples were taken from cheeses after 3, 15, 30, 60 and 90 days, and analysed for lipolysis (as acid degree value) and proteolysis (water-soluble nitrogen, TCA-soluble nitrogen, and PTA-soluble nitrogen). It was found that lipolysis in herby cheeses increased with increasing herb addition, and the increase in lipolysis degree was significant (P < 0.05) in cheese D. Water-soluble N, TCA-soluble N, and PTA-soluble N as indicator of proteolysis degrees were affected significantly (P < 0.05) by increasing herb ratios.     

Methods used to study non-starter microorganisms in cheese: a review

The significance of non-starter lactic acid bacteria (NSLAB), which become the dominant organ-isms in hard cheese varieties during ripening, is still controversial, but they have been shown to contribute to the release of amino acids and to influence flavour development. Since the NSLAB population is essentially uncontrolled, it is likely that at least some of the variability in cheese quality is due to the NSLAB. Several approaches used to assess the significance of NSLAB in cheese ripening are reviewed in this paper.     

Lipolysis and free fatty acid catabolism in cheese: a review of current knowledge

The progress of lipolysis and its effect on flavour development during cheese ripening is reviewed. The review begins by describing the structure and composition of milk fat and thereafter discusses current knowledge regarding the role of various lipolytic agents and their influence on lipolysis in various cheese varieties. While free fatty acids (FFA) liberated during lipolysis directly affect cheese flavour, they are also metabolized to other highly flavoured compounds, including methyl ketones and lactones. The pathways of FFA catabolism and the effect of these catabolic products on cheese flavour are discussed. Finally, the current methods for the quantification of FFA in cheese are reviewed and compared.     

Effect of paracasein degradation on sensory properties of Gouda cheese

The relation between the sensory quality of Gouda cheese and the extent of paracasein degradation, i. e., the content of soluble N, peptide N, amino acid N and amine N, was studied. The above-mentioned parameters of paracasein degradation differently determined the sensory properties of Gouda cheese. The flavour of cheese after 6-week ripening depended to the largest extent on the content of amine N and soluble N. The effect of the content of peptide N on cheese flavour was smaller but statistically significant. Also the smell of Gouda cheese was to the largest extent correlated to the content of amine N. A dependence between smell and the content of peptide N was found only in the cheeses after 4-week ripening. None of the sensory quality parameters of the examined cheeses depended on the content of amino acid N.     

The manufacture of Ras cheese from gamma irradiated milk

Cheese milk exposed to gamma irradiation at a dose of 0·5 Mrad was used in the manufacture of Ras cheese. Quality and ripening of cheese made from irradiated milk were compared with those of cheese made from heat-treated milk.Gamma irradiation of cheese milk reduced the total bacterial count and spore formers by 98·98% and 95·77%, respectively, and eliminated the coliform and pathogenic bacteria. This treatment slightly increased the acid and peroxide values of milk fat, as well as the time required for complete coagulation of milk.An oxidized flavour in the fresh and 1-month-old gamma-irradiated milk (GIM) cheese disappeared during ripening. At the end of ripening, GIM cheese had a better consistency and increased flavour compared with cheese made from heated milk.Ras cheese made from GIM differed little in gross chemical composition but contained higher concentrations of soluble nitrogen compounds and of Free Fatty Acids than the control. Irradiation had a stimulating effect on the total, proteolytic and lipolytic bacterial counts during cheese ripening.     

Sensory properties of Cheddar cheese: changes during maturation

The aroma, flavour and texture of 16 samples of commercial Cheddar cheese have been profiled after ripening at 10 °C for 3, 4, 6, 8, 10 and 12 months. Systematic changes in sensory character have been studied and the main changes during maturation identified. Although sensory character changed slowly during ripening, assessment early in the maturation period was an unreliable estimate of ultimate sensory character. Progressive changes in Cheddar aroma and flavour, creamy flavour, acid flavour and mouth-coating character were noted during ripening. Changes in minor components of aroma and flavour were also observed but, on average, were small. Two samples eventually developed marked rancid character and another became excessively bitter. The relation between gross composition of the cheese and sensory properties was investigated. In the early stages of ripening, the ratings for Cheddar flavour and mouth-coating character were associated with the salt content of the cheese and with the concentration of fat in dry matter. However, as the cheese matured these associations weakened.     

The Traditional Cheeses of Turkey: Southeast Anatolia Region

This study aims to bring together the types of cheese produced in the Southeastern Anatolia Region, which is rich in dairy products. Five different types of cheese were identified within this remit. These are: Urfa White Cheese, Antep Sιkma Cheese, Örgü (Eritme) Cheese, Otlu Cheese, and Künefe Cheese. Despite the relatively low number of types of cheese, the Region's cheese is renowned throughout Turkey. This publication covers the production, physical structure, and appearance of local cheeses, and the chemical and microbiological properties of some of the cheeses.     

Cheese yeasts

Numerous traditionally aged cheeses are surface ripened and develop a biofilm, known as the cheese rind, on their surfaces. The rind of such cheeses comprises a complex community of bacterial and fungal species that are jointly responsible for the typical characteristics of the various cheese varieties. Surface ripening starts directly after brining with the rapid colonization of the cheese surface by yeasts. The initially dominant yeasts are acid and salt-tolerant and are capable of metabolizing the lactate produced by the starter lactic acid bacteria and of producing NH₃ from amino acids. Both processes cause the pH of the cheese surface to rise dramatically. This so-called deacidification process enables the establishment of a salt-tolerant, Gram-positive bacterial community that is less acid-tolerant. Over the past decade, knowledge of yeast diversity in cheeses has increased considerably. The yeast species with the highest prevalence on surface-ripened cheeses are Debaryomyces hansenii and Geotrichum candidum, but up to 30 species can be found. In the cheese core, only lactose-fermenting yeasts, such as Kluyveromyces marxianus, are expected to grow. Yeasts are recognized as having an indispensable impact on the development of cheese flavour and texture because of their deacidifying, proteolytic, and/or lipolytic activity. Yeasts are used not only in the production of surface-ripened cheeses but also as adjunct cultures in the vat milk in order to modify ripening behaviour and flavour of the cheese. However, yeasts may also be responsible for spoilage of cheese, causing early blowing, off-flavour, brown discolouration, and other visible alterations of cheese.     

Biochemistry of cheese ripening

Rennet-coagulated cheeses are ripened for periods ranging from about two weeks to two or more years depending on variety. During ripening, microbiological and biochemical changes occur that result in the development of the flavour and texture characteristic of the variety. Biochemical changes in cheese during ripening may be grouped into primary (lipolysis, proteolysis and metabolism of residual lactose and of lactate and citrate) or secondary (metabolism of fatty acids and of amino acids) events. Residual lactose is metabolized rapidly to lactate during the early stages of ripening. Lactate is an important precursor for a series of reactions including racemization, oxidation or microbial metabolism. Citrate metabolism is of great importance in certain varieties. Lipolysis in cheese is catalysed by lipases from various source, particularly the milk and cheese microflora, and, in varieties where this coagulant is used, by enzymes from rennet paste. Proteolysis is the most complex biochemical event that occurs during ripening and is catalysed by enzymes from residual coagulant, the milk (particularly plasmin) and proteinases and peptidases from lactic acid bacteria and, in certain varieties, other microorganisms that are encouraged to grow in or on the cheese. Secondary reactions lead to the production of volatile flavour compounds and pathways for the production of flavour compounds from fatty acids and amino acids are also reviewed.     

Microbial proteinases as agents for accelerated cheese ripening

Taste panel data confirm that commercial preparations of Bacillus subtilis neutral proteinase can accelerate flavour development in Cheddar cheese without defect formation. The influence of the enzyme on the rate of ripening can be controlled by varying the cheese storage temperature. Fungal acid proteinase gives bitter cheese without enhancing typical flavour, even when used at concentrations corresponding to 5×and 25× less than the optimum neutral proteinase activity. Bacterial alkaline proteinase and broadspecificity proteinase produced bitter cheese but the latter enzyme also enhanced the intensity of typical flavour .     

Microbiological and biochemical changes in herby cheese during ripening

The aim of this study was to determine and compare the microbiological, biochemical and sensory characteristics of herby cheese made with two different methods. In the first method (M1), milk and herbs were pasteurized at 65°C for 30 min, and Lactococcus lactis subsp. lactis and L. lactis subsp. cremoris were added as starter culture at an inoculum ratio of 1.5%. In the second method (M2), the conventional cheesemaking was applied. Microbiological and biochemical changes were monitored throughout the ripening period of 90 days. Samples were taken from cheeses on days 1, 15, 30, 60, and 90. At the end of ripening, sensory characteristics of cheeses manufactured with both methods were evaluated. The obtained results suggested that most changes in pH, titratable acidity, and dry matter contents of cheese varieties were not found to differ statistically significant, but the difference in salt content was significant (P < 0.01). Total aerobic count, lactic acid bacteria, Staphylococcus aureus, coliforms, moulds, yeasts, proteolytic and lipolytic microorganism counts were lower in M1 cheese samples than those of M2 cheese samples (P < 0.01). The numbers of psychrotrophic microorganism in both cheese types were not found to differ significantly. Moreover, the results suggested that there were significant differences (P < 0.01) in the degrees of proteolysis and lipolysis of the cheese varieties. High proteolysis and lipolysis rates were monitored in the traditional cheese samples. However, there were no significant differences between the sensory characteristics of cheese samples.     

An accurate account of mass loss during cheese ripening described using the reaction engineering approach (REA)‐based model

Cheese ripening is an important step in cheese making for modifying surface and curd properties. Due to physical, chemical and biological changes, mass loss usually occurs during the process. Although these changes are essential for developing the texture and flavour of cheese, mass loss decreases product yields. A reliable mathematical model is used to quantify mass loss during cheese ripening so that the processing conditions can be fine‐tuned to achieve the desirable throughput. In this study, for the first time, the reaction engineering approach (REA)‐based model is applied to model the cheese ripening. The study shows that the REA‐based model is accurate to model cheese ripening of Camembert and French smear cheese. In addition, the REA is able to model the cheese ripening under time‐varying environmental conditions. For this purpose, the equilibrium activation energy is evaluated according to the corresponding humidity and temperature in each period, while the same relative activation energy for ripening under constant environmental conditions is implemented. The REA is a simple yet effective approach to model the simultaneous heat and mass transfer process accompanied by chemical and biological reactions. Considering its effectiveness, the REA can be applied in industrial settings for predicting mass loss during cheese ripening.     

Interests in Geotrichum candidum for cheese technology

The wide genotypic and phenotypic diversity of Geotrichum candidum strains does not facilitate its classification as yeast or a yeast-like fungus that is still a matter of debate. Whatever its classification, G. candidum possesses many different metabolic pathways that are of particular interest to the dairy industry. G. candidum is of importance in the maturation of cheese, and much is known about its direct contribution to cheese ripening and flavour formation. Its diverse metabolic potential means that G. candidum can play an important role in the ripening of many soft and semi-hard cheeses and make a positive contribution to the development of taste and aroma. It may also influence the growth of other microorganisms, both valuable and detrimental. The significance of the presence of G. candidum in cheese depends on the particular type of production and on the presence of biotypes featuring specific types of metabolism. However, in situ metabolic pathways involved in cheese ripening and their regulations are mainly unknown. The information available provides a good understanding of the potential of G. candidum strains that are used in cheese manufacture, and permits a better choice of strain depending on the characteristics required. The biochemical activities of G. candidum and its application in the dairy industry are presented in this review.     

干酪的成熟,风味与微生物及其酶的关系

本文对干酪的成熟、风味与微生物及其酶的关系进行了综述；讨论了如何缩短干酪的成熟期并改善干酪的风味；另外，本文也报道了干酪工艺学的新理论和新进展。