The aim of the Food Chemistry & Technology Department is to help food processors maintain competitive advantage and secure premium markets. Our Dairy research focuses on cheese, infant formula and dairy based ingredients; Meat research, focusing on quality, whole chain management and recovering value from meat processing streams; Cereal research focusing on product quality and innovation in the bakery industry

Recent Submissions

  • Effects of dielectric barrier discharge (DBD) generated plasma on microbial reduction and quality parameters of fresh mackerel (Scomber scombrus) fillets

    Albertos, Irene; Martín-Diana, AnaBelen; Cullen, P.J.; Tiwari, Brijesh; Ojha, S. K.; Bourke, Paula; Álvarez, Carlos; Rico, Daniel; National Institute for Food and Agricultural Research (Elsevier, 2017-07-04)
    The effect of atmospheric cold plasma generated by a novel in-package dielectric barrier discharge (DBD) on microbial and quality parameters of mackerel fillets was investigated. DBD voltage (70 kV and 80 kV) and treatment time (1, 3 and 5 min) were studied. Within 24 h of DBD treatment, spoilage bacteria (total aerobic psychrotrophic, Pseudomonas and lactic acid bacteria) were significantly reduced. However, significant effects on lipid oxidation parameters (PV, Dienes) were observed for the treated samples. Both studied treatment factors, treatment voltage and time, significantly affected anti-microbial efficacy and lipid oxidation. Nevertheless, no changes in pH or colour (except for L*) were observed. These results suggest atmospheric cold plasma generated by DBD could be implemented as technology for fish processing, retaining product quality over its shelf life. However, further investigations are needed in order to implement this technology and to control and mitigate its limitations, mainly associated to increased oxidation.
  • Effect of non-thermal plasma technology on microbial inactivation and total phenolic content of model liquid food and black pepper grains

    Charoux, Clementine M.G.; Free, Louis; Hinds, Laura M.; Vijayaraghavan, Rajani K.; Daniels, Stephen; O'Donnell, Colm P.; Tiwari, Brijesh; Department of Agriculture, Food and the Marine. (Elsevier, 2019-10-12)
    The objectives of this study were to investigate the effects of cold plasma technology on the growth and survival rates of vegetative cells and spores, and total phenolic content of black pepper grains. Plasma treatment was carried out using a non-thermal plasma jet system operating at 20 kHz using atmospheric air at a flow of 11 L/min. Two matrices were used, a model liquid food system and black pepper grains, both inoculated with Bacillus subtilis vegetative cells and spores. The samples were treated at 15 and 30 kV for 3–20 min. The plate count method was used to observe the colony-forming units at selected storage times i.e. at 1, 24 and 48 h post treatment at 4 °C. The highest log reduction was observed at 24 h post treatment, i.e. 2.92 log reduction. A 1 log reduction was achieved in the case of black pepper inoculated with spores for all selected storage times. No significant differences in total phenolic content were observed between treated and non-treated samples (p > 0.05). Optical emission spectroscopy was used to detect reactive species which could be responsible for cell death. Atomic oxygen, atomic nitrogen, hydroxyl radicals, nitrite oxide and nitrate were detected in light emitted from the plasma. Cell membrane damage caused by non-thermal plasma technology was observed using scanning electron microscopy. This study concludes that cold plasma technology has potential for industry application in food processing to reduce microbial loads in dried foods with limited impacts on food quality.
  • Influence of Supplemental Feed Choice for Pasture-Based Cows on the Fatty Acid and Volatile Profile of Milk

    O'Callaghan, Tom F.; Mannion, David; Apopei, Diana; McCarthy, Noel A.; Hogan, Sean A.; Kilcawley, Kieran N; Egan, Michael; Irish Dairy Levy; Teagasc Walsh Fellowship Programme (MDPI, 2019-04-22)
    The purpose of this study was to examine the impact of a variety of supplemental feeds on the composition and quality of milk in a pasture-based dairy system. Four pasture-supplemented feeding systems were compared: Group 1 supplementation with 16% crude protein parlour concentrate (CONC); Group 2 supplementation with palm kernel expeller plus parlour concentrate (PKE); Group 3 supplemented with soya hulls plus parlour concentrate (SOYA); Group 4 was supplemented with molassed beet pulp plus parlour concentrate (BEET). Supplemental feeding system was demonstrated to have a significant effect on the size of native casein micelles and the gelation properties of milks. While CONC feeding produced significantly higher casein micelle size, gel strength (Young’s Modulus) was significantly negatively correlated with casein micelle size. Supplemental feeding system had a significant effect on a number of fatty acids (FA) and indices derived therefrom, including total saturated and unsaturated fatty acids, de novo produced FA, omega 3, and omega 6 FA. The volatile profile of milks was also affected by supplemental feed choice, whereby multivariate analysis demonstrated that the CONC diet was distinctly different to that of the PALM, SOYA, and BEET milks. Multivariate analysis demonstrated that it is possible to distinguish milks from different pasture-supplemented feeding systems by their FA profile.
  • Food texture as affected by ohmic heating: Mechanisms involved, recent findings, benefits, and limitations

    Gavahian, Mohsen; Tiwari, Brijesh; Chu, Yan-Hwa; Ting, Yuwen; Farahnaky, Asgar; Ministry of Economic Affairs, Taiwan; 107-EC-17-A-22-0332; 108-EC-17-A-22-0332 (Elsevier, 2019-02-10)
    Background: Food texture is an important quality characteristic that affects sensory perception and consumer satisfaction. Thermal processing applies to food material for several reasons including palatability improvement and shelf life extension. Ohmic heating is an energy- and time-saving technique that was previously proposed as an alternative to conventional heating methods in the food industry. Scope and approach: Investigating the effects of ohmic processes on food quality parameters, such as texture, is an important step towards the industrial adaptation of ohmic heating technology. This review focuses specifically on the effects of ohmic heating on food texture and tries to elucidate the mechanisms behind the changes in textural attributes during an ohmic process as compared to the classical heating method. Key findings and conclusions: Achieving a predefined product texture in a shorter time and the uniformity of product texture are among the benefits of ohmic heating. However, several challenges (e.g. the possibility of negative effects on the chemical composition of the product and high capital investment) should be addressed for the industrial adoption of this emerging technology.
  • Effects of transglutaminase pre-crosslinking on salt-induced gelation of soy protein isolate emulsion

    Luo, Kaiyun; Liu, Shutao; Miao, Song; Adhikari, Benu; Wang, Xufeng; Chen, Jie; National Natural Science Foundation of China; National High-Tech Research and Development Program of China; National Natural Science Foundation of China; NSFC, 31271946; et al. (Elsevier, 2019-07-09)
    The salt-induced gelation behavior of soy protein isolate (SPI) emulsions was markedly influenced by microbial transglutaminase (TGase) pre-crosslinking. Rheological data showed that when SPI emulsions were incubated with TGase at low concentrations (1 and 3 U/g protein) at 50 °C for 30 min prior to gelation, no change in storage modulus (G′), but enhanced resistance to deformation of the gels was observed. Extensive crosslinking by TGase (5 U/g protein) resulted in severe decreases in gel firmness and fracture properties (yielding stress and strain), likely due to the impairment of hydrophobic bonds and the formation of coarse networks. The water-holding capacity of the gels was significantly enhanced by increased concentrations of TGase. Interactive force analysis indicated that non-covalent interactions and disulfide bonds are the primary forces involved in CaSO4-induced SPI emulsion gel, but TGase treatment may limit hydrophobic interactions within the gel network. These results are of great potential value for the application of TGase in the food industry.
  • Influence of particle size on the physicochemical properties and stickiness of dairy powders

    O'Donoghue, Laura; Haque, Md Kamrul; Kennedy, Deirdre; Laffir, Fathima R.; Hogan, S. A.; O'Mahoney, James A.; Murphy, Eoin G.; Enterprise Ireland; TC/2014/0016. (Elsevier, 2019-07-12)
    The compositional and physicochemical properties of different whey permeate (WPP), demineralised whey (DWP) and skim milk powder (SMP) size fractions were investigated. Bulk composition of WPP and DWP was significantly (P < 0.05) influenced by powder particle size; smaller particles had higher protein and lower lactose contents. Microscopic observations showed that WPP and DWP contained both larger lactose crystals and smaller amorphous particles. Bulk composition of SMP did not vary with particle size. Surface composition of the smallest SMP fraction (<75 μm) showed significantly lower protein (−9%) and higher fat (+5%) coverage compared with non-fractionated powders. For all powders, smaller particles were more susceptible to sticking. Hygroscopicity of SMP was not affected by particle size; hygroscopicity of semi-crystalline powders was inversely related to particle size. This study provides insights into differences between size fractions of dairy powders, which can potentially impact the sticking/caking behaviour of fine particles during processing.
  • Influence of buttermilk powder or buttermilk addition on phospholipid content, chemical and bio-chemical composition and bacterial viability in Cheddar style-cheese

    Hickey, Cian D.; Diehl, B.W.K.; Nuzzo, Marine; Millqvist-Feurby, A.; Wilkinson, Martin G.; Sheehan, Jeremiah J.; Dairy Levy Trust (Elsevier, 2017-09-27)
    The effect of buttermilk powder addition post-curd formation or buttermilk addition to cheese milk on total and individual phospholipid content, chemical composition, enzyme activity, microbial populations and microstructure within Cheddar-style cheese was investigated. Buttermilk or buttermilk powder addition resulted in significant increases in total phospholipid content and their distribution throughout the cheese matrix. Addition of 10% buttermilk powder resulted in higher phospholipid content, moisture, pH and salt in moisture levels, and lower fat, fat in dry matter, L. helveticus and non-starter bacteria levels in cheeses. Buttermilk powder inclusion resulted in lower pH 4.6/Soluble Nitrogen (SN) levels and significantly lower free amino acid levels in 10% buttermilk powder cheeses. Buttermilk addition provided a more porous cheese microstructure with greater fat globule coalescence and increased free fat pools, while also increasing moisture and decreasing protein, fat and pH levels. Addition of buttermilk in liquid or powdered form offers potential for new cheeses with associated health benefits.
  • Dairy cow feeding system alters the characteristics of low-heat skim milk powder and processability of reconstituted skim milk

    Gulati, Arunima; Hennessy, Deirdre; O'Donovan, Michael; McManus, Jennifer J.; Fenelon, Mark A.; Guinee, Timothy P.; Department of Agriculture, Food and the Marine; Dairy Levy Trust Co-Operative Society Limited; 11/sf/309 (Elsevier, 2019-08-01)
    Low-heat skim milk powder (LHSMP) was manufactured on 3 separate occasions in mid lactation (ML, July 4–20) and late lactation (LL, September 27 to October 7) from bulk milk of 3 spring-calving dairy herds on different feeding systems: grazing on perennial ryegrass (Lolium perenne L.) pasture (GRO), grazing on perennial ryegrass and white clover (Trifolium repens L.) pasture (GRC), and housed indoors and offered total mixed ration (TMR). The resultant powders (GRO-SMP, GRC-SMP, and TMR-SMP) were evaluated for composition and color and for the compositional, physicochemical, and processing characteristics of the reconstituted skim milk (RSM) prepared by dispersing the powders to 10% (wt/wt) in water. Feeding system significantly affected the contents of protein and lactose, the elemental composition, and the color of the LHSMP, as well as the rennet gelation properties of the RSM. The GRO and GRC powders had a higher protein content; lower levels of lactose, iodine, and selenium; and a more yellow-green color (lower a* and higher b* color coordinates) than TMR powder. On reconstitution, the GRO-RSM had higher concentrations of protein, casein, and ionic calcium, and lower concentrations of lactose and nonprotein nitrogen (% of total N). It also produced rennet gels with a higher storage modulus (G′) than the corresponding TMR-RSM. These effects were observed over the combined ML and LL period but varied somewhat during the separate ML and LL periods. Otherwise, feeding system had little or no effect on proportions of individual caseins, concentration of serum casein, casein micelle size, casein hydration, heat coagulation time, or ethanol stability of the RSM at pH 6.2 to 7.2, or on the water-holding capacity, viscosity, and flow behavior of stirred yogurt prepared by starter-induced acidification of RSM. The differences in the functionality of the LHSMP may be of greater or lesser importance depending on the application and the conditions applied during the processing of the RSM.
  • Response surface methodology modeling of protein concentration, coagulum cut size, and set temperature on curd moisture loss kinetics during curd stirring

    Panthi, Ram R.; Kelly, Alan L.; McMahon, Donald; Dai, Xin; Vollmer, Almut H.; Sheehan, Jeremiah J.; Dairy Levy Trust Fund; Utah State University; Teagasc Walsh Fellowship Programme (Elsevier, 2019-03-28)
    The effects of the independent variables protein concentration (4–6%), coagulum cut size (6–18 mm3), and coagulation temperature (28–36°C) on curd moisture loss during in-vat stirring were investigated using response surface methodology. Milk (14 kg) in a cheese vat was rennet coagulated, cut, and stirred as per semihard cheesemaking conditions. During stirring, the moisture content of curd samples was determined every 10 min between 5 and 115 min after cutting. The moisture loss kinetics of curds cut to 6 mm3 followed a logarithmic trend, but the moisture loss of curds from larger cut sizes, 12 or 18 mm3, showed a linear trend. Response surface modeling showed that curd moisture level was positively correlated with cut size and negatively correlated with milk protein level. However, coagulation temperature had a significant negative effect on curd moisture up to 45 min of stirring but not after 55 min (i.e., after cooking). It was shown that curds set at the lower temperature had a slower syneresis rate during the initial stirring compared with curds set at a higher temperature, which could be accelerated by reducing the cut size. This study shows that keeping a fixed cut size at increasing protein concentration decreased the level of curd moisture at a given time during stirring. Therefore, to obtain a uniform curd moisture content at a given stirring time at increasing protein levels, an increased coagulum cut size is required. It was also clear that breakage of the larger curd particles during initial stirring can also significantly influence the curd moisture loss kinetics. Both transmission and scanning electron micrographs of cooked curds (i.e., after 45 min of stirring) showed that the casein micelles were fused at a higher degree in curds coagulated at 36°C compared with 28°C, which confirmed that coagulation temperature causes a marked change in curd microstructure during the earlier stages of stirring. The present study showed the dynamics of curd moisture content during stirring when using protein-concentrated milk at various set temperatures and cut sizes. This provides the basis for achieving a desired curd moisture loss during cheese manufacture using protein-concentrated milk as a means of reducing the effect of seasonal variation in milk for cheesemaking.
  • Effect of reducing daily herbage allowance during early lactation on composition and processing characteristics of milk from spring-calved herds

    Gulati, Arunima; Galvin, Norann; Kennedy, Emer; Lewis, Eva; McManus, Jennifer J.; Fenelon, Mark A.; Guinee, Timothy P.; Department of Agriculture, Food and the Marine; Dairy Levy Trust Co-Operative Society Limited; 11/sf/309 (Elsevier, 2019-01-30)
    The study investigated the effects of reducing daily herbage allowance (DHA) from 15.0 to 11.8 kg dry matter per cow (>3.5 cm post grazing sward height) to a spring-calved herd during early lactation on the composition, rennet coagulability and heat stability characteristics of milk during early lactation (EL, 29–70 days in milk, DIM), mid lactation (ML, 78–183 DIM), and late lactation (LL, 205–267 DIM). Samples of milk were taken at approximate 10 d intervals during EL and at 1–3 week intervals during ML and LL. Reducing DHA led to reductions in milk yield, milk solids yield, and concentrations of protein (∼0.22%, w/w) and casein (0.13%, w/w) during EL. Otherwise, it had little effect on milk composition or on the selected processing characteristics in ML, LL or overall lactation. Stage of lactation resulted in comparatively large changes in most compositional parameters, rennet gelation and heat stability.
  • Optimization of ultrasound-microwave synergistic extraction of prebiotic oligosaccharides from sweet potatoes (Ipomoea batatas L.)

    Guo, Zebin; Zhao, Beibei; Li, Huang; Miao, Song; Zheng, Baodong; FAFU Funds for Distinguished Young Scientists; International Science and Technology Cooperation and Exchange Project of Fujian Agriculture And Forestry University; Science and Technology Project of Fujian Provincial Education Department; xjq201618; KXGH17001; et al. (Elsevier, 2019-03-19)
    In this study, efficient ultrasound–microwave-assisted extraction (UMAE) of prebiotic oligosaccharides from sweet potatoes (Ipomoea batatas L.) was investigated. Response surface methodology was used to optimize the extraction conditions: extraction time, ultrasonic power, and microwave power. The prebiotic effect of extracted oligosaccharides on Bifidobacterium adolescentis was also investigated. The results show that the processing conditions of UMAE for optimum the yields of prebiotic oligosaccharides from sweet potatoes (PPOS4 and PPOS5) and corresponding absorbance (OD) are 100 s extraction time, 300 W ultrasonic power, and 200 W microwave power. Under these conditions, the experimental yields of PPOS4 and PPOS5 and the corresponding OD were 1.472%, 5.476%, and 2.966, respectively, which match the predicted values well. Compared with the conventional hot-water extraction (HWE), microwave-assisted extraction (MAE), and ultrasound assisted extraction (UAE) methods, the UMAE procedure exhibited significantly high extraction efficiency (p < 0.05). Comparison of SEM images of tissues of the sweet potatoes after extractions indicate microfractures and disruption of cell walls in the potato tissues. These results confirm that UMAE has great potential and efficiency in the extraction of bioactive substances in the food and medicinal industries.
  • Recent advances in the application of pulsed light processing for improving food safety and increasing shelf life

    Mahendran, Radhakrishnan; Ratish Ramanan, K.; Barba, Francisco J.; Lorenzo, Jose M.; López-Fernández, Olalla; Munekata, Paulo E. S.; Roohinejad, Shahin; Sant'Ana, Anderson S.; Tiwari, Brijesh; National Council for Scientific and Technological Development; et al. (Elsevier, 2019-03-18)
    Background New technologies of non-thermal disinfection such as pulsed light (PL) have emerged lately as an alternative to traditional (thermal and chemical) disinfection and preservation methods. PL can be used to decontaminate a great variety of foods as well as to decontaminate contact surfaces, thus improving safety in foods and extending their shelf life. Moreover, this technology can prevent or reduce some of the detrimental effects of traditional methods on nutrients and bioactive compounds of food products. Scope and approach The combination of PL with other techniques such as ultraviolet light (UV), thermosonication (TS), pulsed electric fields (PEF), manothermosonication (MTS), etc., can improve the effectiveness of the decontamination process. Therefore, in this review, some of the most relevant studies evaluating the potential application of PL treatments to decontaminate food samples, and its impact of nutritional and physicochemical quality parameters will be discussed. Key findings and conclusions PL treatments are suitable for microbial decontamination in transparent drinks and for surface contaminated foods without complex microstructures. They also can be used for meat, fish and their by-products However, it is still necessary to evaluate the appropriate treatment conditions (number of light flashed, voltage, distance between sample and flash light, spectral range of light flashes and contamination) for each food and microorganism separately to improve the effectiveness and minimize the appearance of negative attributes reducing the quality of product as, in some cases, PL can have a negative effect on the photosensitive compounds and sensory characteristics of food products.
  • Effect of pH and heat treatment on viscosity and heat coagulation properties of milk protein concentrate

    Ho, Quang Tri; Murphy, Kevin M.; Drapala, Kamil P.; O'Callaghan, Tom F.; Fenelon, Mark A.; O'Mahony, James A.; McCarthy, Noel A.; Dairy Processing Technology Centre; Enterprise Ireland; TC/2014/0016 (Elsevier, 2018-06-11)
    The effect of pH, adjusted using either hydrochloric acid (HCl), citric acid or sodium hydroxide, on calcium ion (Ca2+) activity, and consequent changes in viscosity and heat coagulation time (HCT) of milk protein concentrate (MPC) was investigated. Reducing the pH of MPC dispersions resulted in a reduction in their viscosity, which subsequently increased during heat treatment. The maximum heat stability of MPC was observed at pH 6.7. Reducing the pH of MPC from 6.7 to 6.2 resulted in a significant (P < 0.05) increase in Ca2+ activity, and reduction in HCT. Such changes were more extensive using HCl compared with citric acid. Increasing the pH greater than 6.7 also led to a reduction in HCT but a decrease in Ca2+ activity. These results demonstrate the importance of pH adjustment, and choice of acidulant, on Ca2+ activity, viscosity, and heat coagulation properties of MPC concentrates during processing.
  • The effect of direct and indirect heat treatment on the attributes of whey protein beverages

    Kelleher, Clodagh M.; O'Mahony, James A.; Kelly, Alan L.; O'Callaghan, Donal; Kilcawley, Kieran N; McCarthy, Noel A.; Department of Agriculture, Food and the Marine; Teagasc Walsh Fellowship programme; 10 RD TMFRC 703 (Elsevier, 2018-06-11)
    Thermal processing of ready-to-drink high protein beverages can have a substantial impact on the physical and sensory properties of the final product for long-life milks such as extended shelf life and ultra high temperature processed products. Direct and indirect heat treatment technologies were applied to whey protein isolate (WPI) -based beverages containing 4, 6 or 8% (w/w) protein. Lower levels of protein denaturation (66–94%) were observed using direct heating compared with indirect heating (95–99%) across protein levels and heating temperatures (121 and 135 °C final heat). Direct heat treatment resulted in significantly lower viscosity and less extensive changes to the volatile profile, compared with indirect heat treatment. Overall, the application of direct and indirect heat treatment to WPI solutions resulted in significantly different final products in terms of appearance, physical characteristics and volatile profile, with direct heating resulting in many enhanced properties compared with conventional indirect heat treatment.
  • Use of 31P NMR and FTIR to investigate key milk mineral equilibria and their interactions with micellar casein during heat treatment

    Boiani, Mattia; Fenelon, Mark A.; Fitzgerald, Richard J.; Kelly, Philip M.; Teagasc Walsh Fellowship Programme; Department of Agriculture, Food and the Marine (Elsevier, 2018-02-16)
    The thermal treatment of milk is one of the key processes routinely performed in the dairy industry. Several modifications occur in milk during heating, particularly with respect to its mineral equilibrium. As the temperature increases, the solubility of calcium and phosphate decreases leading to precipitation in the casein micelle as casein phosphate nanocluster. Recently, 31P NMR and Fourier Transform Infrared have been demonstrated to be capable of monitoring changes to its nanocluster. In this study, the effect of temperature on nanocluster during heating of milk to temperatures ranging from 25 °C to 80 °C followed by subsequent cooling were studied. It was also demonstrated that key ionic components of the mineral equilibria behaved differently with temperature, e.g., calcium influence was evident only at lower temperature, while the opposite was the case with phosphate. It was also shown that micellar casein concentration was influential at all temperatures, most notably at lower values.
  • Influence of protein standardisation media and heat treatment on viscosity and related physicochemical properties of skim milk concentrate

    Murphy, Kevin M.; Tri Ho, Quang; Drapala, Kamil P.; Keena, Grainne M.; Fenelon, Mark A.; O'Mahony, James A.; McCarthy, Noel A.; Dairy Processing Technology Centre; Enterprise Ireland; TC/2014/0016 (Elsevier, 2018-02-15)
    The effects of heat treatment and protein standardisation on the physical properties of skim milk concentrates were determined. Protein standardisation was carried out by the addition of lactose or milk permeate to skim milk. Unstandardised and standardised skim milk was subjected to heat treatment temperatures of 90 or 120 °C prior to evaporation whereafter the solids content was increased to 46% (w/w). Viscosity data showed non-standardised concentrates had the highest viscosity, followed by skim standardised with milk permeate followed by that standardised with lactose. Thermal treatment at 120 °C also resulted in a higher viscosity than that at 90 °C for all concentrates. Particle size data of evaporated skim milk showed a bimodal size distribution for skim milk standardised with liquid milk permeate, compared with monomodal distribution profiles for unstandardised skim milk and lactose standardised skim milk. Overall, this study showed that protein standardisation and standardisation media significantly affected concentrate properties.
  • Rehydration behaviour of spray-dried micellar casein concentrates produced using microfiltration of skim milk at cold or warm temperatures

    Crowley, Shane V.; Burlot, Esther; Silva, Juliana V.C.; McCarthy, Noel A.; Wijayanti, Heni B.; Fenelon, Mark A.; Kelly, Alan L.; O'Mahony, James A.; Department of Agriculture, Food and the Marine; Enterprise Ireland; et al. (Elsevier, 2018-02-02)
    Microfiltration (MF) of skim milk, when combined with diafiltration (DF), facilitates the manufacture of liquid micellar casein concentrate (MCC), which can be spray-dried into high-protein (≥80% protein, dry-basis) powders. MCC powders rehydrate slowly, which is typically considered a defect by end-users. This study compared the impact of cold (<10 °C) or warm (50 °C) MF/DF on the rehydration characteristics of MCC powders (MCCcold and MCCwarm, respectively). The wetting properties of the MCC powders, measured using optical tensiometry, were found to be equivalent. However, pronounced differences in dispersion characteristics were measured, and, after 90 min rehydration at 50 °C, liberated casein micelles accounted for only 7.5% of total particle volume in MCCwarm compared with 48% in MCCcold. Due to its superior dispersion characteristics, MCCcold yielded 50–60% less sediment during analytical centrifugation experiments. Cold MF/DF may improve the solubility of MCC powders by accelerating the release of casein micelles from powder particles during rehydration.
  • Effect of heat treatment, evaporation and spray drying during skim milk powder manufacture on the compositional and processing characteristics of reconstituted skim milk and concentrate

    Lin, Yingchen; Kelly, Alan L.; O'Mahony, James A.; Guinee, Timothy P.; Dairy Levy Trust Co-Operative Society Limited (Elsevier, 2017-11-06)
    The effects of key manufacturing steps (heat treatment, evaporation and spray drying) during the manufacture of low- and high-heat skim milk powders (SMP) on the physico-chemical and processing characteristics of milk, and concentrates of varying total solids (TS) levels prepared by reconstituting the milk powders, were evaluated. Milk heat treatment had the most pronounced effect, with an increase in severity of heat treatment from 72 °C × 15 s to 120 °C × 120 s, prior to evaporation resulting in higher heat coagulation time (HCT) at pH 6.3–6.6 and ethanol stability (ES) at pH 6.2–6.6, and a marked deterioration of rennet-induced coagulability. Increasing TS of the milk on reconstitution from 9.4 to 25% reduced HCT at pH >6.3 and ES at pH 6.6–7.0, increased ES at pH 6.2–6.4, and led to partial recovery of rennet-coagulability. The results highlight how heat treatment may be used to customise the functionality of SMP to different applications.
  • Effect of coagulant type and level on the properties of half-salt, half-fat Cheddar cheese made with or without adjunct starter: Improving texture and functionality

    McCarthy, Catherine; Wilkinson, M.G.; Guinee, Timothy P.; Department of Agriculture, Food and the Marine; 2012219 (Elsevier, 2017-08-01)
    The potential of increasing proteolysis as a means of enhancing the texture and heat-induced flow of half-fat, half-salt Cheddar cheese made with control culture (CL, Lactococcus lactis subsp. cremoris/lactis) or adjunct culture (AC, CL + Lactobacillus helveticus) was investigated. Proteolysis was altered by substituting bovine chymosin (BC) with camel chymosin (CC), or by a 2.5-fold increase in level of BC. In cheese with CL-culture, increasing BC led to a large increase in pH and more rapid degradation of αS1-casein during maturation, and cheese that was less firm after 180 d. In contrast, substitution of BC with CC in cheeses made with CL-culture had an opposite effect. While chymosin type and level had a similar influence on αS1-casein hydrolysis in the AC-culture cheeses, it did not affect texture or flowability. Grading indicated that cheese made with AC-culture and with a higher level of BC was the most appealing.
  • Interactions of vegetable proteins with other polymers: Structure-function relationships and applications in the food industry

    Lin, Duanquan; Lu, Wei; Kelly, Alan L.; Zhang, Longtao; Zheng, Baodong; Miao, Song; National Natural Science Foundation of China; 31628016 (Elsevier, 2017-08-24)
    Background In recent years, there has been increasing interest in vegetable proteins, due to their various health beneficial functions and wide applications in the food industry. Vegetable proteins combined with other edible polymers can be used to improve the quality and nutritional value of food products. In these complex food systems, interactions between different components are inevitable, and these interactions have a significant influence on the structure and functions of food products. Scope and approach This study reviews the current status of knowledge of interactions between vegetable proteins and other polymers (proteins or polysaccharides) in food systems and the structure of complexes formed by these interactions. The study also provides a comprehensive review of the applications of the complexes. Key findings and conclusions Vegetable proteins display different types of interactions with other polymers (e.g., polysaccharides, or animal proteins) under different conditions, thus forming a variety of complexes with different structures (e.g., double networks, mosaic textures and cross-linked structures), which showed different impact on properties of the final food products and their applications (e.g., substitution for fat, or encapsulation for bioactive ingredients) in the food industry. However, previous studies mainly focused on leguminous proteins and vegetable-protein-based mixtures of two polymers, further studies on other vegetable proteins and more complex food systems containing vegetable proteins and other polymers are required.

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