Changes in lipid fractions and sensory properties of Idiazabal cheese induced by lipase addition

This work studied the addition of an adequate lipase to enhance lipolysis reactions and the development of piquant flavour and sharp odour in Idiazabal cheese, as an alternative to the use of lamb rennet paste. Cheeses were manufactured from bulk raw ewes' milk in 50 l vats with commercial bovine rennet and 80 lipase units of pregastric or 180 lipase units of fungal lipase and ripened for 180 days. A higher lipolytic activity was induced by lipase addition promoting strong changes in odour and flavour attributes. Both fungal and pregastric lipases increased the content of total free fatty acids (FFA), but the fungal lipase released mainly medium- and long-chain FFA. In contrast, the pregastric lipase preferably released short-chain FFA. Diglyceride (DG) content was considerably higher in cheeses made with added pregastric lipase compared with those made with fungal lipase or with no lipase. Monoglycerides (MG) were detected only in cheeses made with either lipase added, reaching comparable concentrations after ripening for 180 days. The cheeses made with pregastric lipase had the highest scores for odour and flavour intensity, and sharp and rennet odours, desirable attributes for the Idiazabal cheese made with lamb rennet paste. None of the texture attributes were significantly influenced by the concentrations of MG and DG in the cheeses made with either lipase. Thus, the pregastric lipase was more appropriate than the fungal lipase to develop a more traditionally-flavoured Idiazabal cheese.     

Flavour development in dairy cream using fish digestive lipases from Chinook salmon (Oncorhynchustshawytscha) and New Zealand hoki (Macruronusnovaezealandiae)

Digestive lipases from Chinook salmon and New Zealand hoki were evaluated as flavour modifying agents in dairy products. Cream was incubated either with fish lipase or commercially available lipases used in dairy flavour development – calf pregastric esterase (Renco™ PGE) and microbial lipase (Palatase® 20,000 L). The fish enzymes were more similar to calf PGE in terms of the total amount and types of fatty acids released over the course of the reaction. Like the pregastric esterase, the fish enzymes released mainly short chain fatty acids. The highest specificity was towards the key dairy product flavour and odour compounds, butanoic and hexanoic acids. The odour intensity of hexanoic acid produced by the salmon lipase, as measured by SPME–GC–MS, was similar to that produced by both Palatase® and PGE. Free fatty acid composition, together with sensory characteristics of lipase-treated creams, demonstrated the potential for flavour enhancement in dairy products using fish lipases.     

The influence of chemical modification on the hydrolysis of fats by pancreatic lipase and pregastric esterase with reference to fat digestion in the pre-ruminant calf

The hydrolysis of various dietary fats and pure triglycerides by pregastric esterase and pancreatic lipase was studied in vitro in conjunction with a series of digestibility trials to examine the effect of various chemical modifications to beef tallow on its digestibility in milk replacers for pre-ruminant calves. Using pure triglycerides, it was shown that pregastric esterase preferentially hydrolyses triglycerides containing short chain fatty acids; the rate was highest with glyceryl tributyrate and decreased markedly with increase in chain length. Using butterfat, tallow and various modified forms of tallow, it was shown that the inclusion of butyric acid in tallow by interesterification, which markedly improved its digestibility, substantially increased its rate of hydrolysis by pregastric esterase. The initial rate of hydrolysis of tallow by pancreatic lipase was substantially less than that of butterfat. Little improvement in the rate of hydrolysis and solubilisation was obtained when the tallow sample was interesterified or when it was supplemented with the long chain fatty acids, myristic and oleic, or with the short chain fatty acid, butyric. A considerable increase in the initial rate of hydrolysis and solubilisation did occur with tallow samples with a reduced content of stearic acid. The results suggest that hydrolysis by pregastric esterase is a major site of discrimination between different fats in the pre-ruminant calf and an important factor in determining overall digestibility.     

Purification and characterization of a pregastric esterase from a hygienized kid rennet paste

Rennet pastes obtained by maceration of gastric tissues from suckling kids are used traditionally to produce some artisanal cheeses in Spain. Besides milk-clotting function, rennet pastes provide proteolytic activity and lipolytic system, essentially pregastric, necessary in the development of piquant flavor typical of these cheeses. A simple and reproducible procedure allows us to obtain a standardized rennet paste that posses the desired activity and is of good microbiological quality. Concomitantly, a kid pregastric esterase (KPGE) was purified to homogeneity. The purification procedure was based on an aqueous extract of hygienized rennet paste (HRP), which was chromatographed on DEAE-Sepharose Fast Flow then adsorbed on phenyl superose followed by a re-chromatography on the same column. The final enzymatic preparation, where the overall activity recovery was 3%, showed a molecular mass of 53 kDa. The highest activity was determined on p-nitrophenyl butyrate, but marked hydrolysis was also detected on beta-naphthyl caprylate. In contrast, low activity on tributyrin (substrate under emulsion form) was detected, thus confirming the esterase character of purified enzyme.     

不同脂肪酶酶解奶油制备奶味香基的研究

选用Hansen calf lipase、Amano lipase A6、Lipozyme RM IM 3种脂肪酶对无水奶油进行适度酶解制备奶味香基。采用气相色谱分析了酶解奶油中游离脂肪酸组成,结合顶空固相微萃取-气相色谱质谱联用技术对酶解奶油中的挥发性风味成分进行研究,并通过感官评价对酶解奶油进行风味剖面分析并对烘焙产品偏好性评定。结果表明:3种脂肪酶选择性酶解产生中短链脂肪酸的能力均较强,其中动物来源的Hansen calf lipase对中短链脂肪酸的选择性酶解能力最高,酶解奶油中短链脂肪酸相对含量为42.9%,且该酶解奶油和烘焙产品具有令人愉悦的奶味和干酪味;3种酶解奶油中的挥发性风味成分主要为脂肪酸、醛类、酮类、内酯类物质。     

EFFECT OF LIPASE ENZYME ON THE RIPENING OF WHITE PICKLED CHEESE

The effect of addition of pregastric lipase enzyme on the accelerated ripening of white pickled cheese was investigated. Commercial pregastric lipase was added to milk before rennet addition at a level of 0,5, 8, 11 g per 100 L of milk and cheeses were made from this milk. Total solids, fat, total nitrogen, salt, titratable acidity, pH and free fatty acids (C₂-C_18:1) were analysed in the samples during 1–90 days of ripening period at 15 days intervals. Total solids, fat, total nitrogen, salt, titratable acidity, and pH of cheeses slightly increased during the ripening period. Free fatty acids and volatile free fatty acid contents in cheeses made from pregastric lipase added milk were affected by pregastric lipase and their contents were increased significantly (P<0.01) during the ripening period. Particularly, when cheese had a high level (11 g per 100 L milk) pregastric lipase, the amounts of butyric, caproic and caprylic acids in white pickled cheese were quite high. The relative amounts of volatile free fatty acids varied with storage time and pregastric lipase levels.     

Lipolysis,proteolysis and sensory properties of ewe’s raw milk cheese (Idiazabal) made with lipase addition

In this paper, we describe the effect of the addition of pregastric lipase on the composition and sensory properties of Idiazabal cheese. Free fatty acids (FFA), partial glycerides, free amino acids (FAA), gross composition and sensory characteristics were determined at different ripening times in cheeses manufactured with three different amounts of commercial animal lipase or with lipase-containing artisanal lamb rennet paste. The addition of lipase increased the content of total FFA, particularly of short-chain FFA, and that of total partial glycerides in cheeses. Unexpectedly, lipase utilization significantly affected total FAA concentration, which decreased in cheeses elaborated with high lipase amount. In general, Val, Glu and Leu were the major FAA, and their concentrations depended, mainly, on ripening time. Lipase addition had significant influence on the sensory characteristics of the cheeses, increasing scores for most of the flavour and odour attributes of the cheese. Principal component analysis (PCA) was done including dry matter, FFA, FAA, partial glycerides and odour and flavour attributes of the cheeses. It indicated that aroma and flavour parameters of Idiazabal cheese and the content of short-chain FFA and diglycerides were highly correlated to first principal component (PC1), while texture parameters, compositional variables and FAA were correlated to the second principal component (PC2).     

Hygienic quality of ewes' milk cheeses manufactured with artisan-produced lamb rennet pastes

The use of artisan-produced lamb rennet pastes, but not any of the other commercial animal rennets, imparts a characteristic flavour to the cheese, so most Mediterranean ewes' milk cheeses are coagulated with this kind of rennet paste. In contrast to the advantages of using lamb or kid rennet pastes from the sensory point of view, questions are still raised as to their hygienic quality. The goal was to examine the microbiological and enzymic quality of lamb rennet pastes prepared by cheese manufacturers for their own use, and evaluate the hygienic quality of raw sheeps' milk cheeses made with them, using Idiazabal cheese as a model. Lamb rennet pastes prepared by artisan cheese makers from the Basque region of Spain (27), and Italy (8) were evaluated. For cheese making experiments 5 different lamb rennet pastes were selected among the 27 samples from the Basque Country region of Spain. Microbiological analyses were carried out on samples from rennet pastes, rennet extracts, milks and cheeses during ripening. Enzymic activities studied in rennet paste were: total coagulating strength and lipase. Analysis of variance and Student's t-tests was performed. The results show that the artisan-produced rennet pastes contain high levels of a variety of microorganisms. After 60 ripening days, which is the minimum ripening period required for Idiazabal cheese prior to its commercialization, no Eschericia coli, Clostridium, Salmonella spp. or Listeria monocytogenes were detected, and levels for the rest of the microorganisms were below the limits of the European legislative standards for cheese manufactured with raw milk. We can conclude that the use of artisan-produced lamb rennet pastes of questionable hygienic quality for the manufacture of raw milk hard cheeses yields products of good hygienic quality.     

Lipolysis of Butter Oil by an Immobilized Kid Goat Pregastric Esterase

ABSTRACT: A kid goat pregastric esterase immobilized in a continuous flow, hollow-fiber reactor was employed to hydrolyze anhydrous milkfat, producing lipolyzed butter oil. The effects of temperature and pH on the rate of lipolysis were monitored by titration of the effluent stream for total acidity. The overall rate of hydrolysis was fastest at 40 °C and pH 6.0. The reaction rate was modeled by an expression of the general Michaelis-Menten form based on a ping pong bi bi mechanism. Nonlinear regression analyses indicated that the experimental data were consistent with the form of the ping pong bi bi mechanism that assumes that the rate-controlling step is acylation of the enzyme.     

Ripening of Camembert-type cheese made from caprine milk using calf rennet or kid rennet as coagulant

Camembert-type cheese was made from caprine milk using either calf rennet or kid 'Grandine' rennet as coagulant. The pH of all cheeses increased throughout ripening and levels of pH 4.6-soluble nitrogen increased from 8.1 to 18.2% of total nitrogen (TN) and from 6.9 to 20% TN for the cheeses made using calf rennet and kid rennet, respectively. Degradation of β-casein, measured by urea–polyacrylamide gel electrophoresis, and total and free amino acids were greater in the cheese made using kid rennet. Production of peptides, analysed by high performance liquid chromatography (HPLC), was slightly more extensive in the Camembert-type cheese made using calf rennet as coagulant. In general, a higher degree of proteolysis was found in Camembert-type cheese made from caprine milk using kid rennet than in cheese made using calf rennet as coagulant.     

Short communication: Sensory profile of raw goat milk cheeses made with artisan kid rennet pastes from commercial-weight animals: Alternative to farmhouse goat cheeses

The loss of traditional kid rennet pastes in the Canary Islands (Spain), as in many other regions, is most likely due to the custom of using abomasa from very young animals killed below desirable commercial weight. In addition, the reasonable price of commercial rennets (CR) has resulted in the loss of typical sensory characteristics for most farmhouse raw goat milk cheeses, placing them at a disadvantage when local and international markets are full of different cheeses, often with aggressive marketing strategies. This paper analyzes the sensory characteristics of raw goat milk cheeses made with rennet pastes prepared from commercial kid abomasa in 2 ways: dried while full of ingested milk [full, commercial, artisan kid rennet (FCKR)], or dried after being emptied of ingested milk and refilled with raw goat milk [empty, commercial, artisan kid rennet (ECKR)]. This latter practice allows the use of empty abomasa, or abomasa with grass, soil, and so on. Sensory profiles of cheeses made with FCKR and ECKR rennets were compared with those made with CR by an expert panel (n = 7). The FCKR and ECKR cheeses had similar sensory profiles. Although scores for FCKR cheeses were somewhat higher than for ECKR cheeses, they were in the range found for traditional cheeses made with rennet prepared with abomasa from very young animals. The sensory profile of CR cheeses was very different. Almost 90% of consumer panelists (n = 90) preferred cheeses made with the experimental rennet pastes. These results demonstrate the possibility to prepare artisan rennet pastes from commercial-weight kids in an easy way for farmhouse cheese makers using local resources that would otherwise be destroyed in abattoirs.     

Influence of lamb rennet paste on the lipolytic and sensory profile of Murcia al Vino cheese

The influence of lamb rennet paste (71.1% chymosin, 177 international milk-clotting units/mL, 4.57U/g of lipase activity) during the ripening of Murcia al Vino goat cheese was studied. The aim of this study was to improve the knowledge of the effect of lamb rennet paste on the lipolytic patterns in this type of cheese by reference to the evolution of total and free fatty acids. A sensory analysis was carried out to compare cheeses made with commercial and paste rennet. The rennet paste showed higher lipolytic activity, enhancing the production of short-chain free fatty acids. In addition, the cheese produced with lamb rennet paste had a slightly more bitter and piquant taste, making it an attractive commercial alternative that can be used to develop new varieties of goat cheese.     

Acceleration of Cheddar Cheese Lipolysis by Using Liposome-entrapped Lipases

ABSTRACT: Two types of lipase (Palatase M and Lipase 50) were encapsulated in liposomes with trapping efficiencies of 35.9 and 40.3%, respectively. The lipases were incorporated into cheese milk at levels of 0.2, 0.5, and 1.0 lipase units/g fat. Treated cheeses had higher moisture and lower protein, fat, and ash contents than the control cheese and they were less firm, but more elastic and cohesive, than the control cheese. Production of free fatty acids was accelerated by the addition of encapsulated enzymes. Cheeses with up to 0.5 lipase unit/g milk fat had slightly better flavor intensities than control cheese. Cheeses with the highest level of Palatase M and Lipase 50 developed a pronounced soapy off-flavor after 2 and 3 mo of ripening, respectively.     

Invited review: The effect of native and nonnative enzymes on the flavor of dried dairy ingredients

Dried dairy ingredients are used in a wide array of foods from soups to bars to beverages. The popularity of dried dairy ingredients, including but not limited to sweet whey powder, whey proteins and milk powders, is increasing. Dried dairy ingredient flavor can carry through into the finished product and influence consumer liking; thus, it is imperative to produce a consistent product with bland flavor. Many different chemical compounds, both desirable and undesirable, contribute to the overall flavor of dried dairy ingredients, making the flavor very complex. Enzymatic reactions play a major role in flavor. Milk contains several native (indigenous) enzymes, such as lactoperoxidase, catalase, xanthine oxidase, proteinases, and lipases, which may affect flavor. In addition, other enzymes are often added to milk or milk products for various functions such as milk clotting (chymosin), bleaching of whey products (fungal peroxidases, catalase to deactivate hydrogen peroxide), flavor (lipases in certain cheeses), or produced during the cheesemaking process from starter culture or nonstarter bacteria. These enzymes and their possible contributions will be discussed in this review. Understanding the sources of flavor is crucial to produce bland, flavorless ingredients.     

Influence of Saccharomyces cerevisiae fermentation products,SmartCare in milk replacer and Original XPC in calf starter,on the performance and health of preweaned Holstein calves challenged with Salmonella enterica serotype Typhimurium

This study was designed to investigate the effects of supplementing SmartCare (SC; Diamond V, Cedar Rapids, IA) in milk replacer and Original XPC (XPC; Diamond V) in calf starter on performance and health of preweaned calves following an oral challenge with Salmonella enterica. The study was performed in two 35-d periods with 30 Holstein bull calves (2 ± 1 d of age) per period. In each period, calves were blocked by location in the barn and randomly assigned to treatments that included control, base milk replacer and calf starter with no added Saccharomyces cerevisiae fermentation products; SC, milk replacer with 1 g of SC/calf per day and base calf starter; and SC+XPC, milk replacer with 1 g of SC/calf per day and calf starter with 0.5% XPC on a dry matter basis. Calves were fed 350 g of milk replacer solids at 14% dry matter twice daily at 0700 and 1700 h. Calf starter and water were offered ad libitum and intakes were recorded daily. Calves were challenged with 108 cfu of sulfamethazine-resistant Salmonella enterica serotype Typhimurium orally on d 14 of the study. Fecal Salmonella shedding was determined on d 14 to 21 (daily), 24, 28, and 35 using selective media. Blood samples were collected on d 0, 7, 14, 16, 18, 21, 24, 28, and 35 and analyzed for hematology; plasma were analyzed for haptoglobin concentrations. All data were reported as CON, SC, and SC+XPC, respectively. Calf starter intake was increased from d 22 to 35 among SC+XPC calves and from d 29 to 35 among SC calves. The SC+XPC calves had a lower neutrophil-to-lymphocyte ratio (0.81, 0.83, and 0.69 ± 0.051) throughout the study. The SC+XPC calves also had lower hematocrits (35.1, 35.3, and 33.4 ± 0.54%) and hemoglobin concentrations (10.8, 10.6, and 10.1 ± 0.16 mg/dL) throughout the study. We found a tendency for calves fed SC and SC+XPC to have more solid fecal scores during the week after the challenge. We observed no treatment or treatment × time differences on plasma haptoglobin concentrations (63, 48, and 60 ± 0.5 μg/mL). No treatment differences were observed in the fecal shedding of the Salmonella; however, we noted a tendency for a treatment difference in the percentage of calves positive for Salmonella present in the ileal tissue at d 21 after the challenge (25, 50, and 60%). Supplementing preweaned Holstein calves with both SC in milk replacer and XPC in calf starter improved starter intake and improved fecal consistency immediately after a mild Salmonella enterica challenge, but more data are needed to further understand how these yeast fermentation products influence the immune responses to Salmonella enterica.     

Impact of liposome-encapsulated enzyme cocktails on cheddar cheese ripening

Cheddar cheese proteolysis and lipolysis were accelerated using liposome-encapsulated enzymatic cocktails. Flavourzyme, neutral bacterial protease, acid fungal protease and lipase (Palatase M) were individually entrapped in liposomes and added to cheese milk prior to renneting. Flavourzyme was tested alone at three concentrations (Z1, Z2 and Z3 cheeses). Enzyme cocktails consisted of lipase and bacterial protease (BP cheeses), lipase and fungal protease (FP cheeses) or lipase and Flavourzyme (ZP cheeses). The resulting cheeses were chemically, rheologically and organoleptically evaluated during 3 months of ripening at 8 °C. Levels of free fatty acids and appearance of bitter and astringent peptides were measured. Certain enzyme treatments (BP and ZP) resulted in cheeses with more mature texture and higher flavor intensity in a shorter time compared with control cheeses. No bitter defect was detected except in 90-day-old FP cheese. A full aged Cheddar flavor was developed in Z3 and ZP cheeses, while treatment BP led to strong typical Cheddar flavor by the second month and did not exhibit any off-flavor when ripening was extended for a further month.     

Changes in the free amino acid content during ripening of Idiazabal cheese: influence of starter and rennet type

The effect of starter and rennet type on free amino acid release during ripening of Idiazabal cheese was studied. Four batches of cheeses were manufactured depending on the rennet used, commercial calf rennet or artisanal lamb rennet, and the addition or not of starter culture. Cheese samples contained 24 individual free amino acids Leu, Glu, Val and Phe showing the highest contents during the ripening. The results indicated that the release of the free amino acids during ripening was strongly affected by starter added to the cheeses, and that this effect varied markedly with the rennet used for cheesemaking. Total amounts of free amino acids were higher for the cheeses made with commercial calf rennet than for those made with artisanal lamb rennet, regardless of starter addition. Likewise, the highest total free amino acid levels were found in the cheeses made with starter, regardless of the type of rennet used.     

Concentrations of Volatile 4‐Alkyl‐Branched Fatty Acids in Sheep and Goat Milk and Dairy Products

Goat and sheep milk and dairy products thereof are characterized by a strong and unique flavor. In this context, the volatile minor fatty acid 4‐ethyloctanoic acid plays a prominent role along with 4‐methyloctanoic acid when both are present in free form. Using a novel GC/MS method in the selected ion‐monitoring mode, previously developed for sheep subcutaneous adipose tissue, we were able to analyze the total concentrations of these flavor‐relevant minor fatty acids as methyl esters in goat and sheep milk as well as in their products. Differences between the concentrations and ratios of 4‐methyloctanoic acid and 4‐ethyloctanoic acid in goat milk (n = 4), goat cheese (n = 4), sheep milk (n = 2), and sheep cheese (n = 4) were observed. Goat milk and cheese resulted in higher concentrations for both fatty acids (190 to 480 μg/g milk fat) and smaller 4‐Me‐8:0 to 4‐Et‐8:0 ratios (1.4 to 2.7) compared to sheep milk and cheese (78 to 220 μg/g milk fat; 4‐Me‐8:0 to 4‐Et‐8:0 ratio: 15 to 42). In all samples, the concentration of 4‐Me‐8:0 exceeded the one of 4‐Et‐8:0. However, due to its lower flavor threshold value the contribution of 4‐Et‐8:0 to the flavor was generally >76%. The calculated flavor values were >1400 for goat milk and cheeses and >200 for sheep milk and cheeses. In goat milk and its products, only a proportion of <0.1% 4‐alkyl‐branched fatty acids present in free form in the goat milk and <0.5% in the sheep samples would be sufficient to generate the characteristic goaty flavor. Parameters that promote or prevent the release of 4‐Me‐8:0, and especially 4‐Et‐8:0, will be decisive for the flavor in the resulting dairy product.     

Nutritional and sensory characteristics of Minas fresh cheese made with goat milk,cow milk,or a mixture of both

This study aimed to assess and compare the nutritional, technological, and sensory characteristics of Minas fresh cheese made with goat milk, cow milk, or a mixture of the two stored in cold conditions for 21 d. The yield and centesimal composition of the cheeses were not affected by the type of milk used in their preparation. Reductions were observed in the moisture content, pH, proteolysis index, and instrumental hardness; moreover, increases were observed in the syneresis, acidity index, and depth of proteolysis index in all cheeses. The percentages of caprylic, capric, oleic, and linoleic fatty acids were higher in goat milk cheese and cheese made with a mixture of goat and cow milk compared with cow milk cheese, and a sensory evaluation revealed differences in color, flavor, and aroma between the cheeses. The preparation of Minas fresh cheese with a mixture of goat and cow milk can be a viable alternative for dairy products in the market that can be characterized as high-quality products that meet consumer demands.     

The Inhibitory Effects of Brans and Their Aqueous Extracts on the Lipolysis of Tributyrin Catalyzed by Calf Pregastric Lipase

The ability of red and white wheat brans and oat bran to inhibit calf pregastric lipase (CPGL)‐catalyzed hydrolysis of tributyrin has been studied in vitro at pH 6.5, 37 °C. Brans that had been presoaked in Bis‐Tris buffer at pH 6.5, 4 °C reduced CPGL activity by 13% to 20% after being soaked for 0.25 h and by 17% to 30% after being soaked for 24 h. Maximum reduction of CPGL activity was seen within 2 to 5 min incubation between coarse red wheat bran and CPGL. The results are discussed in terms of likely inhibitory components within the brans and their water‐soluble components and their roles in inhibiting pregastric and other lipase‐catalyzed hydrolysis of dietary lipids.