Alistair Carr - Academia.edu (original) (raw)
Papers by Alistair Carr
Trends in Food Science and Technology, Aug 1, 2023
Acta horticulturae, Jul 1, 2016
We noted a significant reduction in the rate of anthocyanin and chlorogenic acid degradation attr... more We noted a significant reduction in the rate of anthocyanin and chlorogenic acid degradation attributable to the enzyme polyphenol oxidase (PPO) in frozen, thawed blueberries (Vaccinium corymbosum) when assessed at 4°C, compared with 20-40°C. We also noted a soft gel that formed in blueberry homogenates only at low temperatures. We propose that the reduction in rate of anthocyanin and chlorogenic acid degradation in frozen, thawed tissue at low temperatures is a consequence not only of the reduced rate of activity of PPO at these temperatures but also of the slow rate of diffusion of PPO through the apoplast following low-methoxy pectin gelation. We note that calcium pectate gels become firmer as the temperature falls below ambient. We suggest that a possible contributor to the reduced rate of fruit softening found at cold storage temperatures may also be an increase in pectin gel viscosity in the apoplast in vivo with a consequential reduction in mobility of wall-degrading enzymes. Viscous drag is likely to be highly significant in the constrained volume of the apoplast.
Food Research International, Jul 1, 2023
Elsevier eBooks, 2017
This chapter describes the steps involved in the cheese making process, explaining their purpose ... more This chapter describes the steps involved in the cheese making process, explaining their purpose and then describes the equipment and manufacturing processes that have been developed to facilitate large scale cheese manufacture. The initial focus is on the common processing steps to the end of the vat stage of manufacture, including descriptions of common cheese vat configurations. This is followed by discussion of the technology used for postvat processing for different cheese groups including dry salt varieties (cheddaring, stirring, milling, salting, block forming and packaging) and brine salt varieties (prepressing, block filling, pressing and brining). Continuous or semicontinuous production methods are described as an alternative to the traditional batch process. A section is also dedicated to processing equipment for pasta filata cheeses, such as cooker-stretchers and extruders. The chapter then moves to a discussion of recent processing developments designed to optimize cheese offerings with an end customer or consumer in mind, such as individually quick-frozen cheese shreds for pizza use and multistage drying of cheese ingredients for processed cheese manufacture. This is followed by a review of more recent technological advances in cheese manufacturing wherein the entire cheese processing is reenvisioned. Such processes include the uncoupling of curd formation from renneting and the removal of separate curd formation and dewheying operations in processes that are made possible by borrowing technologies traditionally used only in the manufacture of noncheese dairy products.
Food Chemistry, Dec 1, 2017
The oxidation potential of iron fortified goat and cow milks and casein phosphopeptides obtained ... more The oxidation potential of iron fortified goat and cow milks and casein phosphopeptides obtained from each species of milk was determined using malondialdehyde as an oxidation product marker. There was a reduction in oxidation when iron was 'bound' to milk or peptides compared to free ferrous sulphate in solution. However, goat milk produced significantly lower amounts of malondialdehyde of 0.46±0.04μgMDA/ml after 3days at 30°C compared to the blank of 1.25±0.16μgMDA/ml. The goat peptides produced non-significantly different levels of malondialdehyde compared to the blank containing no ferrous sulphate.
Journal of Dairy Science, Apr 1, 2017
We isolated goat phosphopeptides via calcium and ethanol precipitation from a caseinate digest an... more We isolated goat phosphopeptides via calcium and ethanol precipitation from a caseinate digest and investigated their feasibility as an iron-fortification ingredient in nutritional foods. Goat tryptic-digested phosphopeptides could bind 54.37 ± 0.50 mg of Fe/g of protein compared with goat milk, which could bind 3.83 ± 0.01 mg of Fe/g of protein, indicating that isolation did increase iron binding. However, the >13-fold increase in iron binding was only partly explained by the increased concentration of phosphoserine-rich residues in the isolated fraction: we observed a 77% increase in serine residue content and a 5.9-fold increase in phosphorus in the goat peptide isolate compared with the starting caseinate material. We investigated the effect of potential industrial processing conditions (including heating, cooling, holding time, and processing order) on iron binding by the tryptic-digested phosphopeptides. In addition, we tested the effect of ionic strength and the addition of peptides to a milk system to understand how food formulations could affect iron binding.
Soft Matter, 2018
The casein micelle is a flexible construct, with its key structural components being casein prote... more The casein micelle is a flexible construct, with its key structural components being casein proteins and colloidal calcium phosphate nanoclusters.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2017
Cold soluble and insoluble caseinates were isolated via cold acid precipitation Calcium has an ef... more Cold soluble and insoluble caseinates were isolated via cold acid precipitation Calcium has an effect on the caseinate structure above a critical concentration Particle growth increased with a higher ratio of cold insoluble to soluble caseinate The aggregate was found to form incompressible regions within the structure ABSTRACT Insights into the structure of caseinate aggregates have been obtained from small angle X-ray scattering (SAXS) with complementary measurements obtained by turbidity and dynamic light scattering (DLS). The caseinate precipitation method produced a cold insoluble and cold soluble caseinate (CN) fraction. The caseinates were then recombined in ratios of these fractions from 0 % to 100 % cold soluble CN (3.3 % w/w total protein), and calcium was added up to 22 mM. This allowed individual structural features due to calcium and/or protein to be identified as the relative concentrations of each component were varied in a controlled fashion. SAXS analysis indicated the presence of scattering objects on three different length scales in the system: a feature from the largest objects which was ascribed to the overall SAXS model Physical model Lvl. 1
Journal of Dairy Science, 2017
Soft Matter, 2016
An in-depth, critical review of model-dependent fitting of small-angle X-ray scattering (SAXS) da... more An in-depth, critical review of model-dependent fitting of small-angle X-ray scattering (SAXS) data of bovine skim milk has led us to develop a new mathematical model for interpreting these data. Calcium-edge resonant soft X-ray scattering data provides unequivocal evidence as to the shape and location of the scattering due to colloidal calcium phosphate, which is manifested as a correlation peak centred at q = 0.035 Å(-1). In SAXS data this feature is seldom seen, although most literature studies attribute another feature centred at q = 0.08-0.1 Å(-1) to CCP. This work shows that the major SAXS features are due to protein arrangements: the casein micelle itself; internal regions approximately 20 nm in size, separated by water channels; and protein structures which are inhomogeneous on a 1-3 nm length scale. The assignment of these features is consistent with their behaviour under various conditions, including hydration time after reconstitution, addition of EDTA (a Ca-chelating agent), addition of urea, and reduction of pH.
The rheological properties of milk, dairy products, dairy process streams and food ingredients de... more The rheological properties of milk, dairy products, dairy process streams and food ingredients derived from milk are important for the efficient processing of dairy products, as well as yielding products with desirable properties. For protein-rich dairy powders, it is generally more economic to process concentrated streams. Consequently, knowledge of the factors that affect their viscosity and performance as ingredients is important. The viscosity of concentrated solutions can be very sensitive to relatively minor alterations to any protein interactions, such as the degree of aggregation or altering the ratio of whey protein to casein, within the protein phase of the mixture. Many of the observed effects can be traced back to the fundamental properties of the particular proteins involved and follow well-known physical principles. In each section of this chapter, the fundamental aspects of the behaviour of the relevant milk proteins are outlined, followed by a brief consideration of ...
La presente invention concerne un procede de preparation d'un hydrolysat proteique de lactose... more La presente invention concerne un procede de preparation d'un hydrolysat proteique de lactoserum a partir d'un substrat d'isolat proteique de lactoserum (WPI). Cet hydrolysat presente des proprietes gustatives, des caracteristiques fonctionnelles et une capacite d'inhibition d'ACE-I ameliorees.
A process for preparing a product of milk protein concentrate (MPC) or isolated milk protein (APL... more A process for preparing a product of milk protein concentrate (MPC) or isolated milk protein (APL) dry with improved solubility comprising: (a) providing an APL or MPC having at least 70% dry matter as milk protein in aqueous solution / suspension; (B) adding at least one monovalent salt in an amount that confers enhanced product solubility when dried; and (c) drying the product, wherein the amount of cation added is 0, 013-0, 30 moles of cation per 100g protein.
Cheese: Chemistry, Physics and Microbiology, 2004
Abstract This chapter describes the steps involved in the cheese making process, explaining their... more Abstract This chapter describes the steps involved in the cheese making process, explaining their purpose and then describes the equipment and manufacturing processes that have been developed to facilitate large scale cheese manufacture. The initial focus is on the common processing steps to the end of the vat stage of manufacture, including descriptions of common cheese vat configurations. This is followed by discussion of the technology used for postvat processing for different cheese groups including dry salt varieties (cheddaring, stirring, milling, salting, block forming and packaging) and brine salt varieties (prepressing, block filling, pressing and brining). Continuous or semicontinuous production methods are described as an alternative to the traditional batch process. A section is also dedicated to processing equipment for pasta filata cheeses, such as cooker-stretchers and extruders. The chapter then moves to a discussion of recent processing developments designed to optimize cheese offerings with an end customer or consumer in mind, such as individually quick-frozen cheese shreds for pizza use and multistage drying of cheese ingredients for processed cheese manufacture. This is followed by a review of more recent technological advances in cheese manufacturing wherein the entire cheese processing is reenvisioned. Such processes include the uncoupling of curd formation from renneting and the removal of separate curd formation and dewheying operations in processes that are made possible by borrowing technologies traditionally used only in the manufacture of noncheese dairy products.
International Dairy Journal
Abstract Plasmin-induced hydrolysis of casein in milk can lead to many defects including proteoly... more Abstract Plasmin-induced hydrolysis of casein in milk can lead to many defects including proteolysis, age gelation, and bitterness. The susceptibility of casein to plasmin can be affected by micellar structure and modification of the lysine residues on caseins. Different levels of casein modification and dissociation of the casein micelle structure were achieved through succinylation. Succinylation occurred at residues Lys7, Lys34, Lys36, Lys42, Lys83 and Lys124 in αS1-casein; Lys80, Lys150, Lys152, Lys158 and Lys165 in αS2-casein; Lys28, Lys29, Lys32, Lys99, Lys105, Lys107 and Lys113 in β-casein, as identified using liquid chromatography–tandem mass spectrometry. The dissociation of caseins from the casein micelle reduced steric hindrance and made the protein more readily susceptible to hydrolysis by plasmin. However, the formation of succinyl-lysine rendered β-casein unrecognisable to the substrate-binding pocket of plasmin, resulting in a non-linear decrease in level of hydrolysis because of the competitive effect of micelle dissociation.
Journal of Food Engineering
Trends in Food Science and Technology, Aug 1, 2023
Acta horticulturae, Jul 1, 2016
We noted a significant reduction in the rate of anthocyanin and chlorogenic acid degradation attr... more We noted a significant reduction in the rate of anthocyanin and chlorogenic acid degradation attributable to the enzyme polyphenol oxidase (PPO) in frozen, thawed blueberries (Vaccinium corymbosum) when assessed at 4°C, compared with 20-40°C. We also noted a soft gel that formed in blueberry homogenates only at low temperatures. We propose that the reduction in rate of anthocyanin and chlorogenic acid degradation in frozen, thawed tissue at low temperatures is a consequence not only of the reduced rate of activity of PPO at these temperatures but also of the slow rate of diffusion of PPO through the apoplast following low-methoxy pectin gelation. We note that calcium pectate gels become firmer as the temperature falls below ambient. We suggest that a possible contributor to the reduced rate of fruit softening found at cold storage temperatures may also be an increase in pectin gel viscosity in the apoplast in vivo with a consequential reduction in mobility of wall-degrading enzymes. Viscous drag is likely to be highly significant in the constrained volume of the apoplast.
Food Research International, Jul 1, 2023
Elsevier eBooks, 2017
This chapter describes the steps involved in the cheese making process, explaining their purpose ... more This chapter describes the steps involved in the cheese making process, explaining their purpose and then describes the equipment and manufacturing processes that have been developed to facilitate large scale cheese manufacture. The initial focus is on the common processing steps to the end of the vat stage of manufacture, including descriptions of common cheese vat configurations. This is followed by discussion of the technology used for postvat processing for different cheese groups including dry salt varieties (cheddaring, stirring, milling, salting, block forming and packaging) and brine salt varieties (prepressing, block filling, pressing and brining). Continuous or semicontinuous production methods are described as an alternative to the traditional batch process. A section is also dedicated to processing equipment for pasta filata cheeses, such as cooker-stretchers and extruders. The chapter then moves to a discussion of recent processing developments designed to optimize cheese offerings with an end customer or consumer in mind, such as individually quick-frozen cheese shreds for pizza use and multistage drying of cheese ingredients for processed cheese manufacture. This is followed by a review of more recent technological advances in cheese manufacturing wherein the entire cheese processing is reenvisioned. Such processes include the uncoupling of curd formation from renneting and the removal of separate curd formation and dewheying operations in processes that are made possible by borrowing technologies traditionally used only in the manufacture of noncheese dairy products.
Food Chemistry, Dec 1, 2017
The oxidation potential of iron fortified goat and cow milks and casein phosphopeptides obtained ... more The oxidation potential of iron fortified goat and cow milks and casein phosphopeptides obtained from each species of milk was determined using malondialdehyde as an oxidation product marker. There was a reduction in oxidation when iron was 'bound' to milk or peptides compared to free ferrous sulphate in solution. However, goat milk produced significantly lower amounts of malondialdehyde of 0.46±0.04μgMDA/ml after 3days at 30°C compared to the blank of 1.25±0.16μgMDA/ml. The goat peptides produced non-significantly different levels of malondialdehyde compared to the blank containing no ferrous sulphate.
Journal of Dairy Science, Apr 1, 2017
We isolated goat phosphopeptides via calcium and ethanol precipitation from a caseinate digest an... more We isolated goat phosphopeptides via calcium and ethanol precipitation from a caseinate digest and investigated their feasibility as an iron-fortification ingredient in nutritional foods. Goat tryptic-digested phosphopeptides could bind 54.37 ± 0.50 mg of Fe/g of protein compared with goat milk, which could bind 3.83 ± 0.01 mg of Fe/g of protein, indicating that isolation did increase iron binding. However, the >13-fold increase in iron binding was only partly explained by the increased concentration of phosphoserine-rich residues in the isolated fraction: we observed a 77% increase in serine residue content and a 5.9-fold increase in phosphorus in the goat peptide isolate compared with the starting caseinate material. We investigated the effect of potential industrial processing conditions (including heating, cooling, holding time, and processing order) on iron binding by the tryptic-digested phosphopeptides. In addition, we tested the effect of ionic strength and the addition of peptides to a milk system to understand how food formulations could affect iron binding.
Soft Matter, 2018
The casein micelle is a flexible construct, with its key structural components being casein prote... more The casein micelle is a flexible construct, with its key structural components being casein proteins and colloidal calcium phosphate nanoclusters.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2017
Cold soluble and insoluble caseinates were isolated via cold acid precipitation Calcium has an ef... more Cold soluble and insoluble caseinates were isolated via cold acid precipitation Calcium has an effect on the caseinate structure above a critical concentration Particle growth increased with a higher ratio of cold insoluble to soluble caseinate The aggregate was found to form incompressible regions within the structure ABSTRACT Insights into the structure of caseinate aggregates have been obtained from small angle X-ray scattering (SAXS) with complementary measurements obtained by turbidity and dynamic light scattering (DLS). The caseinate precipitation method produced a cold insoluble and cold soluble caseinate (CN) fraction. The caseinates were then recombined in ratios of these fractions from 0 % to 100 % cold soluble CN (3.3 % w/w total protein), and calcium was added up to 22 mM. This allowed individual structural features due to calcium and/or protein to be identified as the relative concentrations of each component were varied in a controlled fashion. SAXS analysis indicated the presence of scattering objects on three different length scales in the system: a feature from the largest objects which was ascribed to the overall SAXS model Physical model Lvl. 1
Journal of Dairy Science, 2017
Soft Matter, 2016
An in-depth, critical review of model-dependent fitting of small-angle X-ray scattering (SAXS) da... more An in-depth, critical review of model-dependent fitting of small-angle X-ray scattering (SAXS) data of bovine skim milk has led us to develop a new mathematical model for interpreting these data. Calcium-edge resonant soft X-ray scattering data provides unequivocal evidence as to the shape and location of the scattering due to colloidal calcium phosphate, which is manifested as a correlation peak centred at q = 0.035 Å(-1). In SAXS data this feature is seldom seen, although most literature studies attribute another feature centred at q = 0.08-0.1 Å(-1) to CCP. This work shows that the major SAXS features are due to protein arrangements: the casein micelle itself; internal regions approximately 20 nm in size, separated by water channels; and protein structures which are inhomogeneous on a 1-3 nm length scale. The assignment of these features is consistent with their behaviour under various conditions, including hydration time after reconstitution, addition of EDTA (a Ca-chelating agent), addition of urea, and reduction of pH.
The rheological properties of milk, dairy products, dairy process streams and food ingredients de... more The rheological properties of milk, dairy products, dairy process streams and food ingredients derived from milk are important for the efficient processing of dairy products, as well as yielding products with desirable properties. For protein-rich dairy powders, it is generally more economic to process concentrated streams. Consequently, knowledge of the factors that affect their viscosity and performance as ingredients is important. The viscosity of concentrated solutions can be very sensitive to relatively minor alterations to any protein interactions, such as the degree of aggregation or altering the ratio of whey protein to casein, within the protein phase of the mixture. Many of the observed effects can be traced back to the fundamental properties of the particular proteins involved and follow well-known physical principles. In each section of this chapter, the fundamental aspects of the behaviour of the relevant milk proteins are outlined, followed by a brief consideration of ...
La presente invention concerne un procede de preparation d'un hydrolysat proteique de lactose... more La presente invention concerne un procede de preparation d'un hydrolysat proteique de lactoserum a partir d'un substrat d'isolat proteique de lactoserum (WPI). Cet hydrolysat presente des proprietes gustatives, des caracteristiques fonctionnelles et une capacite d'inhibition d'ACE-I ameliorees.
A process for preparing a product of milk protein concentrate (MPC) or isolated milk protein (APL... more A process for preparing a product of milk protein concentrate (MPC) or isolated milk protein (APL) dry with improved solubility comprising: (a) providing an APL or MPC having at least 70% dry matter as milk protein in aqueous solution / suspension; (B) adding at least one monovalent salt in an amount that confers enhanced product solubility when dried; and (c) drying the product, wherein the amount of cation added is 0, 013-0, 30 moles of cation per 100g protein.
Cheese: Chemistry, Physics and Microbiology, 2004
Abstract This chapter describes the steps involved in the cheese making process, explaining their... more Abstract This chapter describes the steps involved in the cheese making process, explaining their purpose and then describes the equipment and manufacturing processes that have been developed to facilitate large scale cheese manufacture. The initial focus is on the common processing steps to the end of the vat stage of manufacture, including descriptions of common cheese vat configurations. This is followed by discussion of the technology used for postvat processing for different cheese groups including dry salt varieties (cheddaring, stirring, milling, salting, block forming and packaging) and brine salt varieties (prepressing, block filling, pressing and brining). Continuous or semicontinuous production methods are described as an alternative to the traditional batch process. A section is also dedicated to processing equipment for pasta filata cheeses, such as cooker-stretchers and extruders. The chapter then moves to a discussion of recent processing developments designed to optimize cheese offerings with an end customer or consumer in mind, such as individually quick-frozen cheese shreds for pizza use and multistage drying of cheese ingredients for processed cheese manufacture. This is followed by a review of more recent technological advances in cheese manufacturing wherein the entire cheese processing is reenvisioned. Such processes include the uncoupling of curd formation from renneting and the removal of separate curd formation and dewheying operations in processes that are made possible by borrowing technologies traditionally used only in the manufacture of noncheese dairy products.
International Dairy Journal
Abstract Plasmin-induced hydrolysis of casein in milk can lead to many defects including proteoly... more Abstract Plasmin-induced hydrolysis of casein in milk can lead to many defects including proteolysis, age gelation, and bitterness. The susceptibility of casein to plasmin can be affected by micellar structure and modification of the lysine residues on caseins. Different levels of casein modification and dissociation of the casein micelle structure were achieved through succinylation. Succinylation occurred at residues Lys7, Lys34, Lys36, Lys42, Lys83 and Lys124 in αS1-casein; Lys80, Lys150, Lys152, Lys158 and Lys165 in αS2-casein; Lys28, Lys29, Lys32, Lys99, Lys105, Lys107 and Lys113 in β-casein, as identified using liquid chromatography–tandem mass spectrometry. The dissociation of caseins from the casein micelle reduced steric hindrance and made the protein more readily susceptible to hydrolysis by plasmin. However, the formation of succinyl-lysine rendered β-casein unrecognisable to the substrate-binding pocket of plasmin, resulting in a non-linear decrease in level of hydrolysis because of the competitive effect of micelle dissociation.
Journal of Food Engineering