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

  • Fluorescence-based analyser as a rapid tool for determining soluble protein content in dairy ingredients and infant milk formula

    Henihan, Lisa E.; O'Donnell, Colm P.; Esquerre, Carlos; Murphy, Eoin; O'Callaghan, Donal; Department of Agriculture, Food and the Marine; 11/F/052 (Elsevier, 2018-12-03)
    Abstract: Milk protein, in particular native whey protein, is of interest to dairy manufacturers as a measure of functional and nutritional quality. However, quantification of soluble whey protein (SP) is time consuming; giving rise to the need to develop rapid, accurate, and portable at-line process analytical technology. In this study, the performance of a fluorescence-based analyser(F) (Amaltheys II, Spectralys Innovations, France) was evaluated for quantification of SPF and whey protein nitrogen index (WPNI)F in skim milk, whey protein concentrate and infant formula powders. Rehydration of powders prior to analysis was a key factor for ensuring repeatability and reproducibility. A comparison of the analyser with reference methods for SPF and WPNIF resulted in coefficient of determination (R2) > 0.993 for both SPKjeldahl method and WPNIGEA. The results show the fluorescence-based analyser to be rapid, compact, and accurate device, suited for providing reliable support to dairy ingredient and infant formula manufacturers. Industrial relevance: The fluorescence based analysis investigated in this article is suitable for application in the dairy industry where it can be used as a rapid, at-line PAT tool for both liquid and powder samples. The technology has the potential to replace well-established methods for measurement of soluble protein. The main benefit to industry is the ability to respond more rapidly to variations in soluble protein without compromising on the accuracy associated with more time consuming methods.
  • Multi-scale structure, pasting and digestibility of adlay (Coixlachryma-jobi L.) seed starch

    Chen, Jicheng; Chen, Yazhen; Ge, Huifang; Wu, Chunhua; Pang, Jie; Miao, Song; Marine High-Tech Industry in Fujian Province; Fujian Natural Science Foundation; Fujian Agriculture and Forestry University; [2004] 03; et al. (Elsevier BV, 2018-11-28)
    The hierarchical structure, pasting and digestibility of adlay seed starch (ASS) were investigated compared with maize starch (MS) and potato starch (PS). ASS exhibited round or polyglonal morphology with apparent pores/channels on the surface. It had a lower amylose content, a looser and more heterogeneous C-type crystalline structure, a higher crystallinity, and a thinner crystalline lamellae. Accordingly, ASS showed a higher slowly digestible starch content combined with less resistant starch fractions, and a decreased pasting temperature, a weakened tendency to retrogradation and an increased pasting stability compared with those of MS and PS. The ASS structure-functionality relationship indicated that the amylose content, double helical orders, crystalline lamellar structure, and surface pinholes should be responsible for ASS specific functionalities including pasting behaviors and in vitro digestibility. ASS showed potential applications in health-promoting foods which required low rearrangement during storage and sustainable energy-providing starch fractions.
  • Emulsifying properties of hemp proteins: Effect of isolation technique

    Dapčević-Hadnađev, Tamara; Dizdar, Manda; Pojić, Milica; Krstonošić, Veljko; Zychowski, Lisa M.; Hadnađev, Miroslav; Provincial Secretariat for Higher Education and Scientific Research, Republic of Serbia; European Union; 142-451-2458/2018-01/02; 692276 (Elsevier, 2018-12-03)
    Hemp protein was isolated from hemp seed meal using two different isolation procedures: alkali extraction/isoelectric precipitation (HPI) and micellization (HMI). The ability of these proteins to form and stabilize 10% (w/w) sunflower oil-in-water emulsions (at pH = 3.0) was studied at three different concentrations, 0.25, 0.75 and 1.5% (w/w), by monitoring emulsion droplet size distribution, microstructural and morphological properties, rheological behaviour and stability against flocculation, coalescence and creaming. In addition, hemp proteins were analysed for water solubility, denaturation degree and surface/interfacial activity. HMI protein, which was found to be less denatured after isolation, exhibited higher solubility and slightly higher surface/interfacial activity than HPI protein. HMI emulsions possessed a smaller volume mean droplet diameter (d4,3 = 1.92–3.42 μm in 2% SDS) than HPI emulsions (d4,3 = 2.25–15.77 μm in 2% SDS). While HMI stabilized emulsions were characterized with individual droplets covered by protein film, both confocal laser scanning microscopy and flocculation indices indicated occurrence of bridging flocculation in HPI stabilized emulsions. Protein aggregation, which induced flocculation of the droplets, contributed to higher apparent viscosity of HPI stabilized emulsions compared to HMI stabilized emulsions. Interestingly, emulsions stabilized with 1.5% (w/w) HPI exhibited much better creaming and coalescence stability than other emulsions due to the formation of a weak transient network of floccules and higher continuous phase viscosity which both suppressed the movement of the droplets.
  • Separation of Oligosaccharides from Lotus Seeds via Medium-pressure Liquid Chromatography Coupled with ELSD and DAD

    Lu, Xu; Zheng, Zhichang; Miao, Song; Li, Huang; Guo, Zebin; Zhang, Yi; Zheng, Yafeng; Zheng, Baodong; Xiao, Jianbo; National Natural Science Foundation of China; et al. (Springer Science, 2017-03-09)
    Lotus seeds were identified by the Ministry of Public Health of China as both food and medicine. One general function of lotus seeds is to improve intestinal health. However, to date, studies evaluating the relationship between bioactive compounds in lotus seeds and the physiological activity of the intestine are limited. In the present study, by using medium pressure liquid chromatography coupled with evaporative light-scattering detector and diode-array detector, five oligosaccharides were isolated and their structures were further characterized by electrospray ionization-mass spectrometry and gas chromatography-mass spectrometry. In vitro testing determined that LOS3-1 and LOS4 elicited relatively good proliferative effects on Lactobacillus delbrueckii subsp. bulgaricus. These results indicated a structure-function relationship between the physiological activity of oligosaccharides in lotus seeds and the number of probiotics applied, thus providing room for improvement of this particular feature. Intestinal probiotics may potentially become a new effective drug target for the regulation of immunity.
  • Rheological properties and structural features of coconut milk emulsions stabilized with maize kernels and starch

    Lu, Xu; Su, Han; Guo, Juanjuan; Tu, Jinjin; Lei, Yi; Zeng, Shaoxiao; Chen, Yingtong; Miao, Song; Zheng, Baodong; China-Ireland International Cooperation Centre for Food Material Science and Structure Design; et al. (Elsevier, 2019-05-16)
    In this study, maize kernels and starch with different amylose contents at the same concentration were added to coconut milk. The nonionic composite surfactants were used to prepare various types of coconut milk beverages with optimal stability, and their fluid properties were studied. The steady and dynamic rheological property tests show that the loss modulus (G″) of coconut milk is larger than the storage modulus (G′), which is suitable for the pseudoplastic fluid model and has a shear thinning effect. As the droplet size of the coconut milk fluid changed by the addition of maize kernels and starch, the color intensity, ζ-potential, interfacial tension and stability of the sample significantly improved. The addition of the maize kernels significantly reduced the size of the droplets (p < 0.05). The potential values of zeta (ζ) and the surface tension of the coconut milk increased. Based on the differential scanning calorimetry (DSC) measurement, the addition of maize kernels leads to an increase in the transition temperature, especially in samples with a high amylose content. The higher transition temperature can be attributed to the formation of some starches and lipids and the partial denaturation of proteins in coconut milk, but phase separation occurs. These results may be helpful for determining the properties of maize kernels in food-containing emulsions (such as sauces, condiments, and beverages) that achieve the goal of physical stability.
  • The application of process analytical technologies (PAT) to the dairy industry for real time product characterization - process viscometry

    O’Shea, Norah; O'Callaghan, Tom F.; Tobin, John; Dairy Processing Technology (DPTC) Centre; Enterprise Ireland; TC/2014/0016 (Elsevier, 2019-05-03)
    The ideal PAT tool is an inline instrument that can monitor and measure process parameters simultaneously in real time while operating in a highly automated environment. Instruments must be of sanitary design, operate robustly within the full process cycle (production and cleaning). Inline determination of the rheological properties of moving fluids (i.e. dairy concentrates) is one of the process parameters where PAT tools can be add real value in terms of optimising process control. Measurement of process viscosity is crucial in the monitoring and control of a variety of concentration processes in the dairy industry. Continuous monitoring of the rheological behaviour of the fluid can allow for optimisation of the process e.g. pumping (avoid pump blockage and failure), evaporation (limit fouling and maximise water removal) and spray drying (avoidance of nozzle fouling). This review concentrates on the state of the art developments being made in the area of process viscometry.
  • Effect of high pressure processing on the safety, shelf life and quality of raw milk

    Stratakos, Alexandros Ch.; Inguglia, Elena S.; Linton, Mark; Tollerton, Joan; Murphy, Liam; Corcionivoschi, Nicolae; Koidis, Anastasios; Tiwari, Brijesh (Elsevier, 2019-01-14)
    High pressure processing (HPP) was investigated as an alternative to standard raw milk processing. Different pressure levels (400–600 MPa) and exposure times (1–5 min) were tested against artificially inoculated pathogenic E. coli, Salmonella and L. monocytogenes. HPP effectively inactivated bacterial concentration by 5 log CFU/ml. The most effective HPP conditions in terms of pathogen reduction were subsequently utilised to determine the effect of pressure on microbiological shelf life, particle size and colour of milk during refrigerated storage. Results were compared to pasteurised and raw milk. HPP (600 MPa for 3 min) also significantly reduced the total viable counts, Enterobacteriaceae, lactic acid bacteria and Pseudomonas spp. in milk thus prolonging the microbiological shelf life of milk by 1 week compared to pasteurised milk. Particle size distribution curves of raw, pasteurised and HPP milk, showed that raw and HPP milk had more similar casein and fat particle sizes compared to pasteurised milk. The results of this study show the possibility of using HPP to eliminate pathogens present in milk while maintaining key quality characteristics similar to those of raw milk.
  • Evaluation of a fluorescence and infrared backscatter sensor to monitor acid induced coagulation of skim milk

    Panikuttira, Bhavya; Payne, Frederick A.; O'Shea, Norah; Tobin, John; O'Donnell, Colm P.; Dairy Processing Technology Centre; TC/2014/0016 (Elsevier, 2019-05-03)
    A prototype sensor that employs both ultraviolet excited fluorescence and infrared light backscatter was evaluated as an in-line process analytical technology (PAT) tool to monitor acid induced coagulation kinetics of skim milk. Coagulation experiments were carried out at 32 °C using three concentrations of glucono-delta-lactone (GDL). Measurement of storage modulus (G′) of acidified skim milk gel was used as a reference rheological method to monitor the coagulation kinetics. Prediction models were developed to predict the times required for acidified skim milk coagulum to reach selected G′ values (0.5 Pa, 1 Pa, 5 Pa, 10 Pa and 15 Pa) using time parameters extracted from the ultraviolet excited fluorescence and infrared light backscatter profiles. A strong correlation was observed between the predicted times developed using time parameters extracted from the prototype sensor profiles and the measured G′ times extracted from the rheometer (R2 = 0.97, standard error of prediction = 2.8 min). This study concluded that the prototype fluorescence and infrared backscatter sensor investigated combined with the developed rheological prediction model can be used as a potential PAT tool for in-line monitoring of coagulation kinetics in the manufacture of acid induced milk gels. Industrial relevance: The prototype fluorescence and infrared backscatter sensor investigated in this study combined with the developed rheological prediction model can be employed to monitor and control coagulation kinetics in a wide range of dairy processing applications including fresh cheese varieties and yoghurt manufacture.
  • Effect of ultrasound on physicochemical properties of emulsion stabilized by fish myofibrillar protein and xanthan gum

    Xiong, Yao; Li, Qianru; Miao, Song; Zhang, Yi; Zheng, Baodong; Zhang, Longtao; Fujian Agriculture and Forestry University; Fujian Provincial Foreign Cooperation Project; Fujian Provincial Science and Technology Program of Regional Development Project; National Natural Science Foundation of China; et al. (Elsevier, 2019-04-30)
    To investigate the effects ultrasound (20 kHz, 150–600 W) on physicochemical properties of emulsion stabilized by myofibrillar protein (MP) and xanthan gum (XG), the emulsions were characterized by Fourier transform infrared (FT-IR) spectroscopy, ζ-potential, particle size, rheology, surface tension, and confocal laser scanning microscopy (CLSM). FT-IR spectra confirmed the complexation of MP and XG, and ultrasound did not change the functional groups in the complexes. The emulsion treated at 300 W showed the best stability, with the lowest particle size, the lowest surface tension (26.7 mNm−1) and the largest ζ-potential absolute value (25.4 mV), that were confirmed in the CLSM photos. Ultrasound reduced the apparent viscosity of the MP-XG emulsions, and the changes of particle size were manifested in flow properties. Generally, ultrasound was successfully applied to improve the physical stability of MP-XG emulsion, which could be used as a novel delivery system for functional material.
  • In vitro digestion of protein-enriched restructured beef steaks with pea protein isolate, rice protein and lentil flour following sous vide processing

    Baugreet, Sephora; Gomez, Carolina; Auty, Mark; Kerry, Joseph P.; Hamill, Ruth M; Brodkorb, Andre; Teagasc Walsh Fellowship Programme; Department of Agriculture, Food and the Marine; 11/F/045 (Elsevier, 2019-04-12)
    The effect of plant protein inclusion in cooked meat upon in vitro gastro-intestinal (GI) digestion was investigated. Pea protein isolate, rice protein and lentil flour were used to increase the protein content in a meat model system restructured using two transglutaminase enzymes [Activa®EB (TG) and Transgluseen™-M (TS)]. Restructured beef steaks were subjected to simulated GI digestion using the static INFOGEST method. Samples taken at different digestion times were analysed using SDS-PAGE, size exclusion-HPLC, free amino acid analysis and microscopy. SDS-PAGE analysis revealed significant protein hydrolysis during GI digestion. Most soluble peptides had a molecular weight smaller than 500 Da, corresponding to peptides of <5 amino acids, regardless of food treatment. The amounts of released, free amino acids isoleucine, lysine, phenylalanine and valine were higher (P < 0.05) in lentil-enriched restructured beef steaks following GI digestion. Confocal laser scanning microscopy (CSLM) revealed pronounced aggregation in digested samples. In vitro digestates of protein-enriched restructured beef steaks showed lower production of small molecular weight peptides. This study demonstrated how the bioaccessibility of protein-enriched restructured beef steaks are influenced by formulation and processing.
  • Principles and mechanisms of ultraviolet light emitting diode technology for food industry applications

    Hinds, Laura M.; O'Donnell, Colm P.; Akhter, Mahbub; Tiwari, Brijesh; Department of Agriculture, Food and the Marine; 14/F/845 (Elsevier, 2019-04-13)
    The application of ultraviolet (UV) light to water, food contact surfaces and medical equipment for microbial inactivation is widely employed. To date, UV disinfection sources employed are primarily low-pressure and medium-pressure mercury lamps; emitting monochromatic and polychromatic light, respectively. Despite the widespread use of mercury lamps, there are multiple drawbacks associated with their use including; high energy consumption, large size which limits reactor design, high heat emission and the presence of mercury. Light emitting diodes (LEDs) have potential for use as a highly efficient UV decontamination technology. Recent advances in semiconductor development have resulted in UV-LEDs becoming more widely available. UV-LEDs emit monochromatic light, which enables customised UV-LED disinfection systems at specific wavelengths to be developed. The application of UV-LEDs for disinfection purposes has been studied in recent years, particularly with respect to water disinfections systems. In this review, studies relating to UV-LED food applications are discussed. Furthermore, the chemical changes induced in foods, as a result of UV treatment, together with advantages and limitations of the technology are outlined.
  • Shelf-life extension of herring (Clupea harengus) using in-package atmospheric plasma technology

    Albertos, Irene; Martin-Diana, A. B.; Cullen, Patrick J.; Tiwari, Brijesh; Ojha, K. Shikha; Bourke, Paula; Rico, D.; Regional Government of Castille and Leon, Spain; NUGAFU-PEP 2011/769 (Elsevier, 2017-09-17)
    Atmospheric cold plasma is a green and emerging technology, highly interesting to the food industry for its application. Dielectric Barrier Discharges (DBD) can generate atmospheric cold plasma inside sealed packages filled with air through the use of high voltages. This study investigated the use of a large gap DBD design to generate a plasma discharge within the headspace of packaged herring fillets, and its effects on microbiological and quality markers of the fish stored for 11 days at 4 °C. DBD plasma treatment conditions were 70 kV or 80 kV for 5 min treatment time. Results showed that the microbial load (total aerobic mesophilic, total aerobic psychrotrophics, Pseudomonas, lactic acid bacteria and Enterobacteriaceae) were significantly (p < 0.05) lower in the treated samples compared to the control samples. However, samples exposed to the lowest applied voltage better retained key quality factors (lower oxidation and less colour modification). DBD-treatment caused a reduction in trapped water in the myofibrillar network (T21), identified using low-field nuclear magnetic resonance of protons (1H LF NMR). The results indicate that in-package plasma treatment could be employed as an effective treatment for reducing spoilage bacteria in fish.
  • Effects of different freshness on the quality of cooked tuna steak

    Miao, Hanlin; Liu, Qin; Bao, Hairong; Wang, Xichang; Miao, Song; National High-tech Research & Development Program of China; #2012AA092302 (Elsevier, 2017-07-10)
    The variation in quality of yellowfin tuna (Thunnus albacares) steaks of different freshness after cooking were studied by analyzing K value, adenosine triphosphate (ATP)-related compounds content, histamine content, sensory quality, E-nose and E-tongue analysis. The results indicated that when the freshness of raw tuna steak decreased from sashimi grade to cooking grade, IMP content significantly decreased whereas HxR content significantly increased after cooking. With the decrease of freshness, K value of the 4th day sashimi-grade tuna and the 6th day cooking-grade tuna increased from 18% and 24% to 27% and 45% respectively after cooking. The higher histamine content in raw tuna steak, the more significantly increased histamine level of cooked tuna was observed. Raw tuna steaks with sashimi grade have significant variation from those with cooking grade in odor and taste by E-nose and E-tongue analysis after cooking The sensory evaluation showed that the freshness of tuna steak significantly influence the cooking quality (p < 0.05).
  • Phytosterol crystallisation within bulk and dispersed triacylglycerol matrices as influenced by oil droplet size and low molecular weight surfactant addition

    Zychowski, Lisa M.; Logan, Amy; Augustin, Mary Ann; Kelly, Alan L.; O'Mahony, James A.; Conn, Charlotte E.; Auty, Mark; Teagasc; Australian Research Council; 6412; et al. (Elsevier, 2018-04-12)
    Phytosterols can lower LDL-cholesterol and are frequently used by the functional food industry. However, little is known regarding how phytosterol crystallisation can be controlled, despite solubilised phytosterols having improved bioaccessibility. This study investigates phytosterol crystallisation in bulk milk fat and in model dairy emulsion systems at two average droplet sizes, 1.0 and 0.2 µm. The effect of lecithin and monoacylglycerol addition on phytosterol crystallisation for both emulsion and bulk systems was also evaluated. Results demonstrated that lecithin and monoacylglycerols enrichment into the bulk system minimised phytosterol crystallisation. However, in emulsions, phytosterol crystallisation was mainly influenced by decreasing the droplet size. Smaller emulsion droplets containing lecithin showed the greatest potential for decreasing phytosterol crystallisation and had improved physicochemical stability. This information can be employed by the functional food industry to minimise phytosterol crystallisation and possibly improve bioaccessibility.
  • Short communication: Multi-component interactions causing solidification during industrial-scale manufacture of pre-crystallized acid whey powders

    Drapala, Kamil P.; Murphy, Kevin M.; Ho, Quang Tri; Crowley, Shane V.; Mulcahy, Shane; McCarthy, Noel; O'Mahony, James A.; Technology Centres Programme; TC/2014/0016 (Elsevier, 2018-10-03)
    Acid whey (AW) is the liquid co-product arising from acid-induced precipitation of casein from skim milk. Further processing of AW is often challenging due to its high mineral content, which can promote aggregation of whey proteins, which contributes to high viscosity of the liquid concentrate during subsequent lactose crystallization and drying steps. This study focuses on mineral precipitation, protein aggregation, and lactose crystallization in liquid AW concentrates (∼55% total solids), and on the microstructure of the final powders from 2 independent industrial-scale trials. These AW concentrates were observed to solidify either during processing or during storage (24 h) of pre-crystallized concentrate. The more rapid solidification in the former was associated with a greater extent of lactose crystallization and a higher ash-to-protein ratio in that concentrate. Confocal laser scanning microscopy analysis indicated the presence of a loose network of protein aggregates (≤10 µm) and lactose crystals (100–300 µm) distributed throughout the solidified AW concentrate. Mineral-based precipitate was also evident, using scanning electron microscopy, at the surface of AW powder particles, indicating the formation of insoluble calcium phosphate during processing. These results provide new information on the composition- and process-dependent physicochemical changes that are useful in designing and optimizing processes for AW.
  • Evaluation of Vis-NIR hyperspectral imaging as a process analytical tool to classify brined pork samples and predict brining salt concentration

    Achata, Eva M.; Inguglia, Elena S.; Esquerre, Carlos; Tiwari, Brijesh; O'Donnell, Colm P.; Department of Agriculture, Food and the Marine; 13/FM/508 (Elsevier, 2018-10-20)
    Hyperspectral imaging in the visible and near infrared spectral range (450–1664 nm) coupled with chemometrics was investigated for classification of brined and non-brined pork loins and prediction of brining salt concentration employed. Hyperspectral images of control, water immersed and brined (5, 10 or 15% salt (w/v)) raw and cooked pork loins from 16 animals were acquired. Partial least squares (PLS) discriminative analysis models were developed to classify brined pork samples and PLS regression models were developed for prediction of brining salt concentration employed. The ensemble Monte Carlo variable selection method (EMCVS) was used to improve the performance of the models developed. Partial least squares (PLS) discriminative analysis models developed correctly classified brined and non-brined samples, the best classification model for raw samples (Sen = 100%, Spec = 100%, G = 1.00) used the 957–1664 nm spectral range, and the best classification model for cooked samples (Sen = 100%, Spec = 100%, G = 1.00) used the 450–960 nm spectral range. The best brining salt concentration prediction models developed for raw (RMSEp 1.9%, R2p 0.92) and cooked (RMSEp 2.6%, R2p 0.83) samples used the 957–1664 nm spectral range. This study demonstrates the high potential of hyperspectral imaging as a process analytical tool to classify brined and non-brined pork loins and predict brining salt concentration employed.
  • Preparation of modified whey protein isolate with gum acacia by ultrasound maillard reaction

    Chen, Weijun; Ma, Xiaobin; Wang, Wenjun; Lv, Ruiling; Guo, Mingming; Ding, Tian; Ye, Xingqian; Miao, Song; Liu, Donghong; National Key Research and Development Program of China; et al. (Elsevier, 2018-10-18)
    Effect of ultrasound treatment on whey protein isolate (WPI)-gum Acacia (GA) conjugation via Maillard reaction was investigated. And the physicochemical properties of the conjugates obtained by ultrasound treatment were compared with those obtained by classical heating. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, high-performance size exclusion chromatography and fourier transform infrared spectroscopy provided evidence on the formation of the Maillard type conjugation. Compared with classical heating, ultrasound treatment could accelerate the glycation reaction between WPI and GA. A degree of graft of 11.20% was reached by classical heating for 48 h, whereas only 20 min was required by ultrasound treatment. Structural analyses suggested that the conjugates obtained by ultrasound treatment had less α-helix content, higher surface hydrophobicity and fluorescence intensity than those obtained by classical heating. Significantly lower level of browning intensity and significantly higher (p < 0.05) level of solubility (under alkaline conditions), thermal stability, emulsifying activity and emulsifying stability were observed for the conjugates obtained by ultrasound treatment as compared with those obtained by classical heating.
  • Comparison of antioxidant activities of bovine whey proteins before and after simulated gastrointestinal digestion

    Corrochano, Alberto R.; Sariçay, Yunus; Arranz, Elena; Kelly, Philip M.; Buckin, Vitaly; Giblin, Linda; Department of Agriculture, Food and the Marine; Teagasc Walsh Fellowship Programme; 13 F 354-WheyGSH (Elsevier, 2018-10-24)
    Oxidative stress caused by free radicals has been implicated in several human disorders. Dietary antioxidants can help the body to counteract those reactive species and reduce oxidative stress. Antioxidant activity is one of the multiple health-promoting attributes assigned to bovine whey products. The present study investigated whether this activity was retained during upper gut transit using a static simulated in vitro gastrointestinal digestion (SGID) model. The capacity to scavenge free radicals and reduce ferric ion of whey protein isolate (WPI), individual whey proteins, and hydrolysates pre- and post-SGID were measured and compared using various antioxidant assays. In addition, the free AA released from individual protein fractions in physiological gut conditions were characterized. Our results indicated that the antioxidant activity of WPI after exposure to the harsh conditions of the upper gut significantly increased compared with intact WPI. From an antioxidant bioactivity viewpoint, this exposure negates the need for prior hydrolysis of WPI. The whey protein α-lactalbumin showed the highest antioxidant properties post-SGID (oxygen radical absorbance capacity = 1,825.94 ± 50.21 μmol of Trolox equivalents/g of powder) of the 4 major whey proteins tested with the release of the highest amount of the antioxidant AA tryptophan, 6.955 μmol of tryptophan/g of protein. Therefore, α-lactalbumin should be the preferred whey protein in food formulations to boost antioxidant defenses.
  • Comparison of the nutritional composition of experimental fermented milk:wheat bulgur blends and commercially available kishk and tarhana products

    O'Callaghan, Yvonne C.; Shevade, Ashwini V.; Guinee, Timothy P.; O'Connor, Tom P.; O'Brien, Nora M.; Department of Agriculture, Food and the Marine; 14/F/805 (Elsevier, 2018-11-05)
    Dried, fermented blends of dairy products and cereals, such as kishk and tarhana, are foodstuffs traditionally consumed in many regions as they possess good nutritional qualities and extended storage stability. This study examined the nutritional composition of kishk or tarhana type products and compared with experimental blends of fermented milk and wheat bulgur containing 60–80% milk. The blends with higher milk contents had levels of protein (18.9%) and fat (5.8%) at the concentrations specified in fortified blended foods as outlined by the World Food Program. Higher milk contents were also associated with higher contents of calcium (323.2 mg/100 g), phosphorus (335.3 mg/100 g), vitamin A (486.7 µg/100 g) and α-tocopherol (174.5 µg/100 g). The nutritional content of the experimental fermented milk:wheat bulgur blends compared favourably with that of the commercial samples. These blends may be suitable as base products, to be fortified with micronutrients, for the development of fortified blended foods (FBFs) for humanitarian distribution.
  • Modelling the changes in viscosity during thermal treatment of milk protein concentrate using kinetic data

    Ho, Quang Tri; Murphy, Kevin M.; Drapala, Kamil P.; Fenelon, Mark A.; O'Mahony, James A.; Tobin, John; McCarthy, Noel; Enterprise Ireland; TC/2014/0016 (Elsevier, 2018-10-24)
    This work aimed to model the effect of heat treatment on viscosity of milk protein concentrate (MPC) using kinetic data. MPC obtained after ultrafiltration was subjected to different time-temperature heat treatment combinations. Heat treatment at high temperature and short time (i.e., 100 or 120 °C×30 s) led to a significant increase in viscosity in MPC systems. Second-order reaction kinetic models proved a better fit than zero- or first-order models when fitted for viscosity response to heat treatment. A distinct deviation in the slope of the Arrhenius plot at 77.9 °C correlated to a significant increase in the rate of viscosity development at temperatures above this, confirming the transition of protein denaturation from the unfolding to the aggregation stage. This study demonstrated that heat-induced viscosity of MPC as a result of protein denaturation/aggregation can be successfully modelled in response to thermal treatment, providing useful new information in predicting the effect of thermal treatment on viscosity of MPC.

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