P.L.H. McSweeney's research while affiliated with University College Cork and other places

Publications (166)

Chapter
The curds for rennet-coagulated cheeses are generally ripened for ∼2 weeks to >2 years depending upon the variety. During ripening, the flavor and texture characteristics of the variety develop. In this article, the principal biochemical pathways for flavor development are discussed. The biochemical pathways that occur in cheese during ripening are...
Article
Nisin is a bacteriocin that is globally employed as a biopreservative in food systems to control gram-positive, and some gram-negative, bacteria. Here we tested the bioactivity of nisin A-producing Lactococcus lactis NZ9700 and producers of bioengineered variants thereof against representatives of the gram-negative genus Thermus, which has been ass...
Article
This study focused on proteolysis in an Irish farmhouse smear-ripened cheese by serial slicing (0.41 mm/slice) the first 2 cm from surface towards the centre of the cheese. Urea-polyacrylamide gel electrophoretograms confirmed higher proteolysis in the outer layers than at the centre. Free amino acid (FAA) analysis confirmed decrease in proteolytic...
Article
Full-text available
Control of acidity is critical for cheese quality, as high acidity can be associated with poor flavor and textural attributes. We investigated an alternative method to control cheese acidity, specifically in low-fat (LF) and reduced-fat (RF) milled curd, direct-salted Gouda cheese, which involved altering the initial lactose content of cheesemilk....
Article
Proteolysis in Danish blue cheese was studied during 9 weeks' ripening. Levels of pH 4.6-soluble N as a percentage of total N increased from 7.2% to 25%, indicating extensive proteolysis. Urea-polyacrylamide gel electrophoretograms confirmed the extent of proteolysis through chymosin and plasmin action early in ripening, but later the action of Pen...
Article
Full-text available
Fermented foods, in particular, surface-ripened cheese, represent a model to explain the metabolic interactions which regulate microbial succession in complex environments. This study explains the role of individual species in a heterogeneous microbial environment, i.e., the exterior of surface-ripened cheese. Through whole-metagenome shotgun seque...
Book
Cheese: Chemistry, Physics and Microbiology, Fourth Edition, provides a comprehensive overview of the chemical, biochemical, microbiological, and physico-chemical aspects of cheese, taking the reader from rennet and acid coagulation of milk, to the role of cheese and related foods in addressing public health issues. The work addresses the science f...
Article
The strains Staphylococcus saprophyticus DPC5671 and Corynebacterium casei DPC5298 were applied in combination with Debaryomyces hansenii DPC6258 to the surface of young Cheddar cheese curd to obtain two different smear-ripened cheeses. A surface microbiota developed over the incubation period, comprising of both yeast and bacteria; pulsed field ge...
Article
The texture, functionality, and quality of Mozzarella cheese are affected by critical parameters such as pH and the rate of acidification. Acidification is typically controlled by the selection of starter culture and temperature used during cheesemaking, as well as techniques such as curd washing or whey dilution, to reduce the residual curd lactos...
Chapter
The milk of all mammals contains lipids but the concentration varies widely between species from ~2 % to >50 % (Table 3.1). The principal function of dietary lipids is to serve as a source of energy for the neonate and the fat content in milk largely reflects the energy requirements of the species, e.g., land animals indigenous to cold environments...
Chapter
Normal bovine milk contains about 3.5 % protein. The concentration changes significantly during lactation, especially during the first few days post-partum; the greatest change occurs in the whey protein fraction. The natural function of milk proteins is to supply young mammals with the essential amino acids required for the development of muscular...
Chapter
Vitamins are organic chemicals required by the body in trace amounts but which cannot be synthesized by the body. The vitamins required for growth and maintenance of health differ between species; compounds regarded as vitamins for one species may be synthesized at adequate rates by other species. For example, only primates and guinea pigs require...
Article
Lactose is the principal carbohydrate in the milk of most mammals, exceptions are the California sea lion and the hooded seal, which are the only significant sources. Milk contains only trace amounts of other sugars, including glucose (50 mg/l) and fructose and glucosamine, galactosamine and N-acetyl neuraminic acid as components of glycoproteins a...
Chapter
Milk is a dilute emulsion consisting of an oil/fat dispersed phase and an aqueous colloidal continuous phase. The physical properties of milk are similar to those of water but are modified by the presence of various solutes (proteins, lactose and salts) in the continuous phase and by the degree of dispersion of the emulsified and colloidal componen...
Chapter
The salts of milk are mainly the phosphates, citrates, chlorides, sulphates, carbonates and bicarbonates of sodium, potassium, calcium and magnesium. Approximately 20 other elements are found in milk in trace quantities, including copper, iron, lead, boron, manganese, zinc, iodine, etc. Strictly speaking, the proteins of milk should be included as...
Book
This book is the most comprehensive introductory text on the chemistry and biochemistry of milk. It provides a comprehensive description of the principal constituents of milk (water, lipids, proteins, lactose, salts, vitamins, indigenous enzymes) and of the chemical aspects of cheese and fermented milks and of various dairy processing operations. I...
Article
Like all other foods of plant or animal origin, milk contains several indigenous enzymes. The principal constituents of milk (lactose, lipids and proteins) can be modified by exogenous enzymes, added to induce specific changes; being a liquid, milk is more amenable to enzyme action than solid foods Exogenous enzymes may also be used to analyse for...
Chapter
Milk has always soured spontaneously but at some point in human history, artisans deliberately caused milk to sour or ferment. Fermentation is one of the oldest methods for preserving milk and probably dates back ~10,000 years to the Middle East where the first evidence of organized food cultivation and production is known to have occurred. Traditi...
Article
The water content of dairy products ranges from ~2.5 to ~94 % (w/w) (Table 7.1) and is the principal component, by weight, in most dairy products, including milk, cream, ice cream, yogurt and most cheeses. The moisture content of foods (or more correctly their water activity, see Sect. 7.3), together with temperature and pH, are of great importance...
Chapter
Despite a significant amount of research in many areas, the definition of a bioactive compound remains ambiguous and unclear (see Guaadaoui et al. 2014). Bioactive compounds in foods are generally regarded as components that affect biological processes or substrates and, hence, have an impact on body function or condition and ultimately health. The...
Chapter
In modern dairy technology, milk is almost always subjected to a heat treatment; typical examples are: thermization (65 ˚C × 15 sec), low temperature – long time pasteurization (65 ˚C × 30 min), high temperature – short time (72 ˚C × 15 sec) pasteurization, ultra-high temperature sterilization (140 ˚C × 5 sec), in-container sterilization (112 ˚C ×...
Chapter
Milk is a fluid secreted by the female of all mammalian species, of which there are more than 4,000, for the primary function of meeting the complete nutritional requirements of the neonate of the species. In addition, milk serves several physiological functions for the neonate. Most of the non-nutritional functions of milk are served by proteins a...
Chapter
Full-text available
Cheese ripening is a complex set of biochemical events that involves at least three fl avor generating pathways: (i) lipolysis, (ii) proteolysis and (iii) metabolism of residual lactose and of lactate and citrate. It is affected by many factors including type and amount of coagulant, presence of starter, adjunct starter and non-starter microorganis...
Article
The objective of this study was to compare the effect of coagulant (bovine calf chymosin, BCC, or camel chymosin, CC), on the functional and sensory properties and performance shelf-life of low-moisture, part-skim (LMPS) Mozzarella. Both chymosins were used at 2 levels [0.05 and 0.037 international milk clotting units (IMCU)/mL], and clotting tempe...
Book
Professor Fox's multi-volume Advanced Dairy Chemistry set was first published in four volumes in the early 1980s. A second edition came out in the early 1990s, and an updated third edition was published a decade later. The set is the leading major reference on dairy chemistry, providing in-depth coverage of milk proteins, lipids, and lactose. The e...
Article
Leuconostoc mesenteroides subsp. cremoris, Leuconostoc pseudomesenteroides and Lactobacillus danicus were grown to early stationary phase in MRS and a cheese based medium (CBM). Lb. danicus had lower aminopeptidase and aminotransferase activity after growth in CBM compared with growth in MRS. Lb. danicus showed aminotransferase activity on all 20 a...
Article
Full-text available
Due to practical and hygienic uses in storage and marketing, cheese maker preference for the use of vacuum packaging instead of the brining method has increased significantly in recent years. The objective of the paper was to study and compare the chemistry, biochemistry, and microstructure of Mihalic cheeses ripened in vacuum packaging or under br...
Article
Development of a pink color defect is an intermittent but persistent defect in a wide range of ripened cheese varieties (Swiss, Cheddar, Grana, and Italian types) which may or may not contain an added colorant, e.g., annatto. Pink discoloration results in downgrading or rejection of a product with consequential economic loss to producers. Pink disc...
Article
Rennet-coagulated cheeses are ripened for periods varying from two weeks to two or more years during which the flavour and texture characteristics of the variety develop. Microbial changes during ripening include a decline in starter organisms and an increase in numbers of adventitious non-starter bacteria and, often, the development of a desirable...
Article
Full-text available
Fat-reduced cheeses often suffer from undesirable texture, flavor, and cooking properties. Exopolysaccharides (EPS) produced by starter strains have been proposed as a mechanism to increase yield and to improve the texture and cooking properties of reduced-fat cheeses. The objective of this work was to assess the influence of an exopolysaccharide o...
Article
Semi-hard cheeses were manufactured from caprine milk and bovine milk mixed in ratios of 100:0; 75:25; 50:50; 25:75; 0:100 (caprine:bovine) and ripened at 12 °C for 150 d. Substitution of up to 75% bovine for caprine milks had no significant effect on levels of cheese protein, moisture-in-non-fat substances, salt, pH, whiteness, total or individual...
Article
Cheddar-type cheeses were manufactured using fermentation-produced camel or calf chymosin. There were no significant differences in the composition and pH between the cheeses made with either coagulant. The extent of primary proteolysis was significantly lower in cheeses made with camel chymosin than in cheeses made with calf chymosin. There were l...
Article
a b s t r a c t The microbial, compositional and biochemical profiles of São Jorge cheese (PDO) obtained from three dis-tinct cheese plants, throughout the ripening period were determined. Fully ripened cheeses (i.e. by 130 days) contained a total of 3.1 Â 10 7 CFU g À1 mesophilic bacteria, and a decrease in moisture content, con-comitantly with an...
Article
The rheological properties of rennet-induced skim milk gels made from milk protein concentrate (MPC) solutions with αs- (i.e., α1s- + αs2-):p-casein ratios of 1.00:0.70 (LBCN), 1.00:0.80 (MBCN) and 1.00:0.87 (HBCN), each having identical pH, concentrations of total calcium and casein (2.4%), were studied using dynamic low amplitude oscillatory rheo...
Article
Strongly proteolytic starters seem to improve the growth of nonstarter lactobacilli during cheese ripening, but no information is available on the impact of the nonmicrobial proteases usually active in cheese on their development. In the current study, the influence of chymosin- and plasmin-mediated proteolysis on the growth and biochemical activit...
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Full-text available
The chemistry, biochemistry and volatile compounds of Kuflu cheese, a Turkish mould-ripened variety were studied. A total of 29 samples were analysed and the titratable acidity, moisture, salt-in-moisture, fat-in-dry matter and total protein contents (as mean values) were 0.96%, 49.97%, 7.49%, 12.18% and 37.84%, respectively, and the pH of the chee...
Article
The objective of this study was to develop a method to measure the oxidation-reduction (redox) potential of hard cheeses such as cheddar and to investigate the impact on this parameter of measurement temperature, and factors associated with electrochemical cell design such as distance between reference and working electrodes and depth into the chee...
Article
The influence of the cheese-making process, ripening conditions and primary starter on the viability and proteolytic activity of an adjunct culture of Lactobacillus plantarum I91 was assessed in two miniature cheese models, representative of Cremoso Argentino and Cheddar cheeses. Cheeses with and without adjunct culture were made under controlled m...
Article
The objective of this study was to investigate the influence of several types of emulsifying salts (ES) on the texture of nonfat process cheese (NFPC). Improperly produced nonfat cheese tends to exhibit several problems upon baking including stickiness, insufficient or excessive melt, pale color upon cooling, formation of a dry skin (skinning) ofte...
Article
The effects of 35 strains of indigenous bacteria on proteolysis in model Toma Piemontese cheese were studied at 30 and 60 days of ripening. Proteolysis was assessed by urea-polyacrylamide gel electrophoresis (PAGE) of the pH 4.6-insoluble fractions of cheese, by reversed-phase high performance liquid chromatography (RP-HPLC) of the pH 4.6-soluble f...
Article
The effects of varying the ratio of αs1-:β-casein of milk on the Theological and functional properties of cheese were investigated. Directly acidified, fat-free cheeses were manufactured from milk protein concentrate (MPC) solutions with identical concentrations of casein (2.5%), but different αs1-:β-casein ratios. One MPC solution (LBCN) had an αs...
Article
Cheddar cheese ripened at 8 degrees C was sampled at 7, 14, 28, 56, 112, and 168 d and subsequently used for the manufacture of processed cheese. The cheddar cheese samples were analyzed throughout ripening for proteolysis while the textural and rheological properties of the processed cheeses (PCs) were studied. The rate of proteolysis was the grea...
Article
Cell numbers of presumptive lactic acid bacteria varied markedly between 7 natural whey starter cultures (NWSC) used for producing traditional cows' milk Mozzarella cheeses in the Apulia region of Southern Italy. Taxonomic identification revealed a large diversity at species level, including mesophilic and thermophilic lactobacilli, lactococci, str...
Article
The microbial and chemical composition of seven different semi-ripened (45 days) Provola dei Nebrodi Sicilian cheese samples were assessed in order to investigate the diversity of the microbial population in cheese made from different geographical areas throughout Sicily. The samples, which were obtained from seven different Provola dei Nebrodi man...
Article
Thirteen samples of Irish bog butter from various locations were selected, of which nine were dated to the Iron Age (400 BC–500 Cal AD), three to the Medieval Period (1100–1600 Cal AD), and one much later (1520–1800 Cal AD). These contained 94–100% (w/w) fat in crystalline form, and >0.6% (w/w) moisture, and fatty acid profiles were characteristica...
Article
To study the influence of native milk flora on the flavour and texture of raw milk cheese it is necessary to produce milk without its native flora. Three procedures to eliminate native flora from milk can be discernedfrom the literature: aseptically drawn milk, heat treatment of whole milk and physical treatment of skim milk with subsequent additio...
Article
This is the third of a series of three papers on the flavour of milk and dairy products (see also Nursten1 and Urbach2). It deals with the taste of cheeses and so concentrates on the water soluble, non-volatile fraction. Bitterness is the paramount concern, hydrophobic peptides being the principal culprits, but saltiness, sweetness and astringency...
Article
Ten commercial Cheddar cheeses of variable quality differing in fat content and age were subjected to compositional, proteolytic, lipolytic and sensory analyses. The compositional parameters of the full-fat cheeses were predominantly outside those typically associated with good-quality cheese. Sensory analysis discriminated the full-fat cheeses pre...
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Full-text available
Tulum cheeses were manufactured from raw ewe's milk and ripened in goat's skin bags (tulums) or plastic containers to understand the effect of ripening container on the chemical composition, biochemistry, microbiology, and volatile composition of Tulum cheeses during 150 d of ripening. Chemical compositions of the cheeses ripened in tulums were sig...
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Full-text available
This review provides an outline of the principal biochemical changes which occur in various cheeses during ripening including metabolism of residual lactose, conversion of lactate to various products and the metabolism of citrate. The hydrolysis of milk fat to free fatty acids (lipolysis) and their subsequent metabolism to volatile flavour compound...
Article
Seven mozzarella cheeses from the Apulia region were analysed for compositional, microbiological and biochemical characteristics. Mean values for the gross composition of the seven cheeses differed significantly. Moisture was high in most samples, salt levels varied considerably from 1.6% to 0.5%. The pH was high in all samples (6.29-5.82), except...
Article
A novel model system was developed for studying the effects of colloidal Ca phosphate (CCP) concentration on the rheological properties of Cheddar cheese, independent of proteolysis and any gross compositional variation. Cheddar cheese slices (disks; diameter = 50 mm, thickness = 2 mm) were incubated in synthetic Cheddar cheese aqueous phase soluti...
Article
The scientific overview of complex processes for cheese manufacturing and ripening is provided. Milk contains two distinctly different groups of proteins, caseins and whey (non-casein) proteins (WPs), which are insoluble and soluble at pH 4.6 and 20°C respectively. The production of fermented milks and acid curd cheeses probably occurred accidental...
Article
Samples of prepartum secretion, colostrum and mature milk were analysed for variation in activity of cathepsin D and cysteine protease due to lactation stage and somatic cell count (SCC). In spite of considerable variation between animals, cathepsin D activity was found to be highest in prepartum secretion, lowest in colostrum and at intermediate l...
Article
The effect of the native whey proteins α-lactalbumin (α-La), β-lactoglobulin (β-Lg) and bovine serum albumin (BSA) on the aminopeptidase activity of Lactococcus (Lc.) lactis spp. cremoris AM1 was investigated using p-nitroanilide (NA) derivatives of amino acids as substrates. PepN-like activity was decreased by inclusion of mixed whey proteins. Whi...
Book
The Advanced Dairy Chemistry series was first published in four volumes in the 1980s (under the title Developments in Dairy Chemistry) and revised in three volumes in the 1990s. The series is the leading reference on dairy chemistry, providing in-depth coverage of milk proteins, lipids, lactose, water and minor constituents. Advanced Dairy Chemistr...
Chapter
When considering the processing and quality of milk and dairy products, a number of enzymes are of significance. These fall broadly into 3 categories: 1. Indigenous enzymes: Fresh raw bovine milk contains a heterogeneous group of enzymes, derived from various sources. While different authors may use different nomenclature to indicate the origin of...
Article
Miniature (20 g) Cheddar-type cheeses were manufactured using enzymes extracted from the crustacean Munida or chymosin as coagulant. Cheeses were ripened at 8 degrees C and samples were collected for analysis after 2, 6 and 12 weeks. Proteolysis was assessed by urea-polyacrylamide gel electrophoresis, which showed that cheeses manufactured with the...
Article
Full fat, milled-curd Cheddar cheeses (2 kg) were manufactured with 0.0 (control), 0.1, 1.0, or 10.0 micromol of pepstatin (a potent competitive inhibitor of chymosin) added per liter of curds/whey mixture at the start of cooking to obtain residual chymosin levels that were 100, 89, 55, and 16% of the activity in the control cheese, respectively. T...
Article
Reggianito argentino is a hard cooked cheese, which is normally produced with natural 'wild' whey cultures. In the present work, we compared proteolysis during the ripening of cheeses made with natural whey cultures and defined multiple-or single-strain cultures of Lactobacillus helveticus (SF133, 138 and 209). For that purpose, we performed RP-HPL...
Article
Turkish White-brined cheese was manufactured using Lactococcus strains (Lactococcus lactis ssp. lactis NCDO763 plus L. lactis ssp. cremoris SK11 and L. lactis ssp. lactis UC317 plus L. lactis ssp. cremoris HP) or without a starter culture, and ripened for 90 d. It was found that the use of starters significantly influenced the physical, chemical, b...
Article
The effect of proteolytic enzymes from somatic cells on cheese quality was studied. In preliminary experiments, milk and two sodium caseinate systems (pH 6.5 and pH 5.2, the latter in the presence of 5% NaCl) were used as substrates to investigate the proteolytic activity of somatic cells recovered from mastitic milk. Urea-polyacrylamide gel electr...
Article
Full-text available
The appearance of undesirable bitter taste in Ragusano cheese was investigated by comparing the composition of 9 bitter cheeses with that of 9 reference cheeses of good quality by means of chemical, electrophoretic, and chromatographic analyses. Rates of proteolysis were significantly affected in cheeses of different quality. Primary proteolysis, a...
Article
Lactobacillus sanfranciscensis CB1 uses cellobiose and other β-glucosides (methyl-β-glucoside, arbutin, amygdalin and salicin) as carbon sources. A hexameric ca. 288 kDa β-glucosidase was purified to homogeneity from Lact. sanfranciscensis CB1 by four chromatographic steps. The enzyme was optimally active at pH 7.5 and 40°C. It had a pI of ca. 4.38...
Article
This chapter discusses biochemistry of cheese ripening. Biochemical reactions that occur in cheese during ripening are usually grouped into four major categories: (1) glycolysis of residual lactose and catabolism of lactate, (2) catabolism of citrate, which is very important in certain varieties, and (3) lipolysis and the catabolism of free fatty a...
Article
Cheese is the generic name for a group of fermented milk-based food products, produced in a great range of flavours and forms throughout the world. From humble beginnings, i.e. simply as a means of conserving milk constituents, cheese has evolved to become a food of haute cuisine with epicurean qualities, as well as being highly nutritious. Sandine...
Article
This chapter discusses the process of catabolism of amino acids in cheese during ripening. Catabolism of amino acids plays a major role in flavor development in cheese during ripening. In particular, the catabolism of sulphur-containing amino acids (principally methionine), aromatic amino acids, and branched-chain amino acids to flavor, or perhaps...
Article
This chapter discusses metabolism of residual lactose and of lactate and citrate. During the manufacture of cheese curd, lactose is converted to lactic acid (mainly the L-isomer) by the starter bacteria. In the case of Cheddar-type cheeses, most of the lactic acid is produced in the vat before salting and moulding whereas for most other varieties,...
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Full-text available
Chemometric modeling of peptide and free amino acid data was used to study proteolysis in Protected Denomination of Origin Ragusano cheese. Twelve cheeses ripened 3 to 7 mo were selected from local farmers and were analyzed in 4 layers: rind, external, middle, and internal. Proteolysis was significantly affected by cheese layer and age. Significant...
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Full-text available
It is generally believed that enzymes in rennet are largely denatured by cooking during the manufacture of hard cheese. However, typical products of rennet action on αs1-casein have been detected in these varieties. The aim of the present work was to relate residual rennet activity with proteolysis in Reggianito Argentino, a hard cooked cheese. For...
Article
Young Tilsit cheese is traditionally smeared during ripening using smear liquid from older cheese which facilitates the development of surface flora, but this practice is undesirable from the point of view of hygiene. The objectives of this study were to investigate an alternative to this traditional practice involving a defined-strain surface star...
Article
Full-text available
The effects of defined lactococcal starter strains (UC317, NCDO763, HP or SK11) on proteolysis in Turkish White-brined cheese were studied throughout ripening (1, 15, 30, 60 or 90 days). No significant differences were found in the gross compositions of the cheeses made with different strains, although the pH values were slightly different. Proteol...
Article
The presence of the lysosomal cysteine proteinase cathepsin B in milk has been demonstrated recently. The potential significance of this enzyme to proteolysis in milk and dairy products was evaluated by the study of its proteolytic specificity towards the caseins. Bovine cathepsin B (1.4 units mL−1) was added separately to β-casein or αs1-casein (5...
Article
Different authors have demonstrated the potential of adding lactobacilli as adjunct cultures to pasteurized milk used in cheese manufacture. The aim of this work was to observe the effect of the use of a defined-strain starter culture and the addition of an adjunct culture (Lactobacillus plantarum) to cheesemilk in order to determine their effect o...
Chapter
The presence of indigenous proteolytic activity in milk has been recognized since the work of Babcock and Russel in 1897. Some early researchers attributed this activity to bacterial enzymes, but later work proved conclusively the presence of indigenous proteinases in milk. More recent research has indicated two major categories of indigenous prote...
Book
Advanced Dairy Chemistry-l: Proteins is the first volume of the third edition of the series on advanced topics in Dairy Chemistry, which started in 1982 with the publication of Developments in Dairy Chemistry. This series of volume~ is intended to be a coordinated and authoritative treatise on Dairy Chemistry. In the decade since the second edition...