The Teagasc Food Programme focuses on quality, safety and food product innovation. It is undertaken in collaboration with universities and research institutes in Ireland, the European Union and the USA. The Food Programme is internationally competitive from a scientific point of view while being targeted and applied to generate new opportunities for the Irish food industry The Teagasc Food Programme encompasses many aspects of food science and technology: Food Processing and Functionality, Food Safety, Foods for Health, Food Cultures, Food Quality and Structure, Meat and Meat Products, Prepared Consumer Foods. The Food Programme is run from the Teagasc Food Research Centres at Ashtown, Dublin 14 and Moorepark, Fermoy, Co. Cork

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  • Self-Agglomeration in Fluidised Beds after Spray Drying

    Fitzpatrick, John J.; Wu, Shaozong; Cronin, Kevin; Miao, Song; China Scholarship Council; 201606350091 (MDPI AG, 2020-06-05)
    Many powders are produced in spray-drying processes from liquid concentrates. Self-agglomeration can be performed in a fluidised bed where the spray-dried powder is agglomerated using the liquid concentrate as the binder material. This has advantages over traditional wet agglomeration in fluid beds using liquid binders (such as water or sugar solutions). These include thermal energy savings and no additional non-aqueous binder components added. The work presented has two parts. The first part is experimental, which investigated the self-agglomeration of whey protein isolate (WPI) powder as a case-study. It showed that satisfactory agglomeration was achieved with a great improvement in the wettability of the powder. The second part of the work performed thermal energy analysis to estimate the energy saving potential of self-agglomeration, and how this is influenced by binder to powder ratio and binder solids concentration. For the WPI case-study, the analysis showed there is potential for a 19% saving in thermal energy requirement for self-agglomeration in comparison to traditional agglomeration using a water binder.
  • Visible and NIR hyperspectral imaging and chemometrics for prediction of microbial quality of beef Longissimus dorsi muscle under simulated normal and abuse storage conditions

    Achata, Eva M.; Oliveira, Marcia; Esquerre, Carlos A.; Tiwari, Brijesh K; O'Donnell, Colm P.; Irish Department of Agriculture, Food & the Marine; 13/FM/508 (Elsevier BV, 2020-06)
    There is a need to develop a rapid technique to provide real time information on the microbial load of meat along the supply chain. Hyperspectral imaging (HSI) is a rapid, non-destructive technique well suited to food analysis applications. In this study, HSI in both the visible and near infrared spectral ranges, and chemometrics were studied for prediction of the bacterial growth on beef Longissimus dorsi muscle (LD) under simulated normal (4 °C) and abuse (10 °C) storage conditions. Total viable count (TVC) prediction models were developed using partial least squares regression (PLS-R), spectral pre-treatments, band selection and data fusion methods. The best TVC prediction models developed for storage at 4 (RMSEp 0.58 log CFU/g, RPDp 4.13, R2p 0.96), 10 °C (RMSEp 0.97 log CFU/g, RPDp 3.28, R2p 0.94) or at either 4 or 10 °C (RMSEp 0.89 log CFU/g, RPDp 2.27, R2p 0.86) were developed using high-level data fusion of both spectral regions. The use of appropriate spectral pre-treatments and band selection methods was key for robust model development. This study demonstrated the potential of HSI and chemometrics for real time monitoring to predict microbial growth on LD along the meat supply chain.
  • Preparation, structure-property relationships and applications of different emulsion gels: Bulk emulsion gels, emulsion gel particles, and fluid emulsion gels

    Lin, Duanquan; Kelly, Alan L.; Miao, Song; China Scholarship Council; 201708350111 (Elsevier BV, 2020-08)
    Background In recent years, there has been increasing interest in emulsion gels, due to their better stability during storage and potential for prolonged intestinal drug release compared to emulsions. There are three kinds of emulsion gels, classified according to their morphological properties: bulk emulsion gels, emulsion gel particles and liquid emulsion gels. Scope and approach This paper provides a comprehensive review of the mechanisms and procedures of different methods for preparing different emulsion gels and relationships between structures and properties of emulsion gels. The applications of emulsion gels in the food industry are finally discussed. Key findings and conclusions Different emulsion gels result from different preparation methods, and have various structure-property relationships and applications. Many methods can be used to prepare bulk emulsion gels, involving different matrix materials, processing techniques, and purposes. This can result in different structures of gel matrices and emulsion droplets, and interactions between them, which can influence the structures of bulk emulsion gels and then their mechanical and release properties. On the other hand, extrusion and impinging aerosol methods are two methods for preparing emulsion gel particles, while liquid emulsion gels can be prepared by Pickering emulsions and disrupted gel systems. Rheological, syneresis and swelling properties are critical for gel particle suspensions, while flow behavior and release properties are important to liquid emulsion gels. In addition, fat replacements and delivery systems are main applications of emulsion gels in the food industry. However, current research has mainly focused on bulk emulsion gels, so further studies on emulsion gel particles and liquid emulsion gels are required.
  • Effect of concentrations of alginate, soy protein isolate and sunflower oil on water loss, shrinkage, elastic and structural properties of alginate-based emulsion gel beads during gelation

    Lin, Duanquan; Kelly, Alan L.; Maidannyk, Valentyn; Miao, Song; China Scholarship Council; 201708350111 (Elsevier BV, 2020-11)
    The aim of this study was to investigate the influence of concentrations of sodium alginate (0.5%–1.5% in the water phase of an emulsion), soy protein isolate (SPI, 0.5%–2.0% in the water phase) and oil phase (10%–40% in the emulsion) on the properties (including water loss, shrinkage, morphological, elastic, and structural properties) of emulsion gel beads during gelation (0–30 min). Gel beads were prepared with external gelation by dropping emulsions into CaCl2 solutions using pipettes. The Young's modulus of emulsion gel beads kept increasing during gelation before reaching a plateau accompanied by syneresis (i.e., water loss), shrinkage, and structural tightening. SPI absorbed at the surface of oil droplets could prevent re-coalescence of droplets during gelation. Additionally, increasing concentrations of sodium alginate and oil increased the Young's modulus of gel beads. Water loss decreased with increasing contents of alginate, SPI and oil, and shrinkage could be diminished by increasing alginate and oil contents.
  • Use of an NIR MEMS spectrophotometer and visible/NIR hyperspectral imaging systems to predict quality parameters of treated ground peppercorns

    Esquerre, Carlos A.; Achata, Eva M.; García-Vaquero, Marco; Zhang, Zhihang; Tiwari, Brijesh K; O'Donnell, Colm P. (Elsevier BV, 2020-09)
    The aim of this study was to investigate the potential of a micro-electromechanical NIR spectrophotometer (NIR-MEMS) and visible (Vis)/NIR hyperspectral imaging (HSI) systems to predict the moisture content, antioxidant capacity (DPPH, FRAP) and total phenolic content (TPC) of treated ground peppercorns. Partial least squares (PLS) models were developed using spectra from peppercorns treated with hot-air, microwave and cold plasma. The spectra were acquired using three spectroscopy systems: NIR-MEMS (1350–1650 nm), Vis-NIR HSI (450–950 nm) and NIR HSI (957–1664 nm). Very good predictions of TPC (RPD > 3.6) were achieved using NIR-MEMS. The performance of models developed using Vis-NIR HSI and NIR HSI were good or very good for DPPH (RPD > 3.0), FRAP (RPD >2.9) and TPC (RPD > 3.8). This study demonstrated the potential of NIR-MEMS and Vis-NIR/NIR HSI to predict the moisture content, antioxidant capacity and total phenolic content of peppercorns. The spectroscopy technologies investigated are suitable for use as in-line PAT tools to facilitate improved process control and understanding during peppercorn processing.
  • A novel approach for dynamic in-situ surface characterisation of milk protein concentrate hydration and reconstitution using an environmental scanning electron microscope

    Cenini, V.L.; Gallagher, L.; McKerr, G.; McCarthy, Noel; McSweeney, D. J.; Auty, M. A. E.; O'Hagan, M. A. E.; Irish Department of Agriculture, Food and the Marine; Department of Agriculture, Environment and Rural Affairs in Northern Ireland; DAIRY DRY 15-F-679 (Elsevier BV, 2020-11)
    Composition and relative humidity (RH) can have a profound impact on the physical (flowability, stickiness) and functional (reconstitution) properties of milk powder (MP) and therefore its quality, storage stability and shelf-life. Conventional microscopic techniques are not capable of dynamically imaging the effect of RH on MP at high magnification. The aim of this study was to develop a novel method to characterise in-situ and in real time the hydration and reconstitution of five spray-dried milk protein concentrates (MPCs) using an Environmental Scanning Electron Microscope (ESEM). ESEM was employed to observe the surface microstructure of MPC powders with varying protein content (38.63%–80.94%, w/w), at various RH values ranging from 35% to over 100%. MPC powders were imaged by an ESEM without any prior preparation, and with minimal physical sample alteration, thus providing fundamental insights into MPC hydration and reconstitution. ESEM surface analysis showed particle swelling in all MPCs, and that with increasing protein content, hydration and reconstitution efficiency decreased. For the first time, dynamic particle surface fusion was observed. Such fusion can result in stickiness and caking over time. ESEM methods developed here may provide mechanistic insights into the effects of RH during storage. Surface re-arrangement was also observed in all MPCs, but was impeded in MPC70 and MPC80 thus indicating that this is the rate limiting step for MPC reconstitution. This work validates the use of an ESEM to dynamically characterise MPC powder hydration and reconstitution in-situ and in real-time, at both high magnification and spatial resolution.
  • Comparative genomics and gene-trait matching analysis of Bifidobacterium breve from Chinese children

    Liu, Rui; Yang, Bo; STANTON, CATHERINE; Ross, Paul; Zhao, Jianxin; Zhang, Hao; Chen, Wei; National Natural Science Foundation of China; National First-Class Discipline Program of Food Science and Technology; the Fundamental Research Funds for the Central Universities; et al. (Elsevier BV, 2020-08)
    Bifidobacterium breve is one of the dominant Bifidobacterial species in children. In the current work, 46 strains of B. breve isolated from fecal samples of Chinese children were analyzed using whole-genome sequencing and comparative genomics to explore their genetic diversity, as well as genotype and phenotype analysis for carbohydrate utilization and antibiotic tolerance. The phylogenetic tree was independent of region, age and feeding mode, and without any regularity in the clustering of carbohydrates and antibiotics at the genetic level. Based on genotypic-phenotypic correlation analysis, the diversity of glycosyl hydrolases and the ability of strains to metabolize carbohydrates corroborated the predominance of B. breve in the children's intestines. Simultaneously, the sensitivity of strains to antibiotics increased the understanding of its genetic features and provided a potential basis for safety evaluation.
  • Moderate electric fields and ohmic heating as promising fermentation tools

    Gavahian, Mohsen; Tiwari, Brijesh K (Elsevier BV, 2020-08)
    Fermentation is an important bioprocess in food production and its improvements can bring profits to the food industry. Therefore, researchers are exploring the feasibility of applying emerging processing technologies such as moderate electric field (MEF) and ohmic heating to improve this bioprocess. This study demonstrated the current status, potential benefits, mechanisms, and limitations of innovative MEF- and ohmic-assisted fermentation. Research showed that these techniques can positively affect Lactobacillus, Streptococcus, and Saccharomyces fermentations that are involved in the production of bakery (e.g., leavened breads), dairy (e.g., yogurt), and alcoholic products. Also, volumetric ohmic heating can accelerate fermentation by providing optimum fermentation temperatures quickly. MEF-induced stress-response conditions can affect microbial metabolism and fermentation products. Besides, electrical fields may affect the fermentation process by altering the substrate such as releasing its micronutrients. These approaches can be considered prospective industrial fermentation tools. Further economic studies and in-depth research on their effects on fermentation by-products are expected in the near future.
  • Dr. Ahmed Ouali, 1948–2020

    GAGAOUA, Mohammed; Sentandreu, Miguel Angel; Coulis, Gérald; Aubry, Laurent; Astruc, Thierry; Herrera-Mendez, Carlos; Valin, Christian; Benyamin, Yves; Fernandez, Eric; Gaillard-Martinie, Brigitte; et al. (Elsevier BV, 2020-09)
  • Impact of freezing on the physicochemical and functional properties of low–moisture part–skim mozzarella

    To, Chak Ming; Vermeir, Lien; Rebry, Ferre; Kerkaert, Barbara; Van der Meeren, Paul; Guinee, Tim; Flemish Agency for Innovation & Entrepreneurship; Fund for Scientific Research – Flanders; HBC.2017.0297 (Elsevier BV, 2020-07)
    Low–moisture part–skim (LMPS) mozzarella cheeses were held at 4 °C for 0, 2 or 8 d before freezing to −20 °C. The cheeses were frozen at a rate of 0.6, 2.0 or 8.0 °C h−1 and held frozen at −20 °C for 1, 6, 12 or 44 weeks. After freezing, cheeses were stored at 4 °C for 16–37 d, resulting in a total storage time at 4 °C (before and after freezing) of 24–37 d (frozen–thawed mozzarella). Control mozzarella was stored at 4 °C for 25–37 d. The control and frozen–thawed cheeses were assayed for composition, primary proteolysis, moisture distribution, texture profile analysis and melting characteristics after similar storage times at 4 °C. Freezing under the evaluated conditions resulted in reduced firmness of the unheated cheese but did not significantly affect the properties of the heated cheese. The results suggest that freezing may be effectively applied to control or extend the functional shelf–life of LMPS mozzarella shipped to long–distance markets.
  • Seaweeds as promising resource of bioactive compounds: Overview of novel extraction strategies and design of tailored meat products

    Gullón, Beatriz; GAGAOUA, Mohammed; Barba, Francisco J.; Gullón, Patricia; Zhang, Wangang; Lorenzo, José M.; Axencia Galega de Innovación; CYTED; Spanish Ministry of Economy and Competitiveness; Generalitat Valenciana; et al. (Elsevier BV, 2020-06)
    Background Meat and meat products have been recently perceived by consumers as unhealthy foods. To avoid this drawback, the reformulation is a feasible approach that allows obtaining custom meat-based products that incorporate compounds with certain beneficial properties for health and remove other attributes considered negative. In this framework, the edible seaweeds have been proposed to offer interesting possibilities in the meat sector to develop functional foods as they are an excellent natural source of nutrients and biocompounds with myriad functionalities. Scope and approach This review collects aspects related to the recent technologies employed to obtain and isolate biocompounds from seaweeds. The use of whole seaweeds and their bioactive extracts to develop meat foods that confer them health properties while simultaneously reducing components considered unhealthy in meat are reviewed. Furthermore, the prevention of oxidation events was also described. Key findings and conclusions Several studies have demonstrated that the incorporation of whole seaweeds and their bioactives to reformulate meat products is an excellent approach to improve certain nutritional aspects considered “bad”. However, there are still some challenges regarding the organoleptic and sensory properties of the resulting products that affect the consumer acceptability. In conclusion, more research is necessary to overcome these gaps allowing put in the market seaweeds -based meat products.
  • Evaluation of production of Cheddar cheese from micellar casein concentrate

    Li, Bozhao; Waldron, David S.; Tobin, John T.; Subhir, Surabhi; Kelly, Alan L.; McSweeney, Paul L.H.; Department of Agriculture, Food and the Marine; 15F683 (Elsevier BV, 2020-08)
    The production of Cheddar cheese using micellar casein concentrate (MCC), a novel milk ingredient powder with a high casein content (∼92%), was evaluated. Four types of Cheddar cheese were manufactured and ripened for 180 days from the following starting materials: standardised control milk (control), skim milk with cream (SC), reconstituted MCC with cream (MC) and reconstituted low-heat skim milk powder with cream (PC). Only minor differences were found in composition between treatments, but MC cheese showed higher levels of proteolysis compared with other treatments, linked to significantly higher plasmin and chymosin activities. No differences were observed in hardness between treatments (60, 120 and 180 days), but the springiness and cohesiveness of MC and PC cheeses were significantly higher than that of the control and SC cheeses at 60, 120 and 180 days. The use of casein-dominant dairy streams thus has the potential for production of Cheddar cheese with tailored functionality.
  • Symposium review: Dairy-derived oligosaccharides—Their influence on host–microbe interactions in the gastrointestinal tract of infants

    Quinn, Erin M.; Joshi, Lokesh; Hickey, Rita M.; Teagasc Walsh Fellowship Programme; 2013059 (Elsevier, 2020-02-20)
    Oligosaccharides are the third most abundant component in human milk. It is widely accepted that they play several important protective, physiological, and biological roles, including selective growth stimulation of beneficial gut microbiota, inhibition of pathogen adhesion, and immune modulation. However, until recently, very few commercial products on the market have capitalized on these functions. This is mainly because the quantities of human milk oligosaccharides required for clinical trials have been unavailable. Recently, clinical studies have tested the potential beneficial effects of feeding infants formula containing 2′-fucosyllactose, which is the most abundant oligosaccharide in human milk. These studies have opened this field for further well-designed studies, which are required to fully understand the role of human milk oligosaccharides. However, one of the most striking features of human milk is its diversity of oligosaccharides, with over 200 identified to date. It may be that a mixture of oligosaccharides is even more beneficial to infants than a single structure. For this reason, the milk of domestic animals has become a focal point in recent years as an alternative source of complex oligosaccharides with associated biological activity. This review will focus specifically on free oligosaccharides found in bovine and caprine milk and the biological roles associated with such structures. These dairy streams are ideal sources of oligosaccharides, given their wide availability and use in so many regularly consumed dairy products. The aim of this review was to provide an overview of research into the functional role of bovine and caprine milk oligosaccharides in host–microbial interactions in the gut and provide current knowledge related to the isolation of oligosaccharides as ingredients for incorporation in functional or medical foods.
  • Enzymatic degradation of FODMAPS via application of β-fructofuranosidases and α-galactosidases- A fundamental study

    Atzler, Jonas J.; Ispiryan, Lilit; Gallagher, Eimear; Sahin, Aylin W.; Zannini, Emanuele; Arendt, Elke K.; Irish Department of Agriculture, Food and the Marine; 15F602 (Elsevier BV, 2020-09)
    Cereals and pulses often contribute to the intake of Fermentable Oligo-, Di-, Monosaccharides, and Polyols (FODMAPs) due to high amounts of fructans or galactooligosaccharides (GOS). FODMAPs can trigger symptoms of Irritable Bowel Syndrome (IBS) and therefore, the development of foods and beverages with a lower FODMAP-content are favourable for IBS patients. Enzyme technology is a promising tool to reduce the FODMAP-content in foods and to maintain product quality. This fundamental study investigates the efficiency of invertase, inulinase, and α-galactosidase as potential food additives to reduce the total FODMAP content of food ingredients. Extracts of high FODMAP ingredients, such as wheat and lentil, and standard solutions of various fructans and GOS were incubated with invertase, inulinase and α-galactosidase for 1 h and 2 h. Contents of oligosaccharides before and after treatment and related IBS-triggering reaction products were quantified using ion chromatography. Inulinase showed a high degradation yield (over 90% of degradation) for both GOS and fructans. For invertase only low degradation yields were measured. α-Galactosidase showed the highest efficiency in decomposing GOS (100% of degradation) and led to non-IBS triggering degradation products. This indicates a high potential for a combined inulinase/α-galactosidase treatment for products containing both fructans and GOS.
  • Discrimination of five Greek red grape varieties according to the anthocyanin and proanthocyanidin profiles of their skins and seeds

    Kyraleou, Maria; Kallithraka, Stamatina; Gkanidi, Eugenia; Koundouras, Stefanos; Mannion, David T.; Kilcawley, Kieran; State Scholarships Foundation of Greece (Elsevier BV, 2020-09)
    The knowledge of grapes phenolic content is proven to be critical for the vinification process and the improvement of wine quality. This study was undertaken to determine the phenolic composition and to employ the phenolic profile as a varietal discrimination tool in five Greek red grape varieties. Ninety grape samples from two seasons (2017 and 2018) were analyzed after extraction with organic solvents. Their proanthocyanidin profile, expressed as percentages of flavan-3-ols, was determined in both skins and seeds by employing phloroglucinolysis followed by HPLC-UV and MS detection, and anthocyanin profile was identified only in the skin extracts by HPLC-UV. Significant differences were observed in proanthocyanidin and anthocyanin profiles of skin extracts between the samples of different varieties, but not in seeds. (-)-Epicatechin was the main subunit in Mandilaria, Kotsifali, Agiorgitiko and Xinomavro grapes while (-)-epigallocatechin gallate in Mavrotragano. Malvidin-3-O-glucoside was the predominant pigment in all grape samples analyzed with the exception of Kotsifali skin extracts, where peonidin-3-O-glucoside was the most abundant anthocyanin. In addition, Mavrotragano skin extracts were the richest in delphinidin and petunidin-3-O-glucosides, while Agiorgitiko and Xinomavro contained the highest amount of malvidin-3-O-glucoside. The results underline the significance of the skin phenolic composition as a tool for the discrimination of the Greek red grape varieties.
  • Conjugation of soy protein isolate (SPI) with pectin by ultrasound treatment

    Ma, Xiaobin; Hou, Furong; Zhao, Huanhuan; Wang, Danli; Chen, Weijun; Miao, Song; Liu, Donghong; National Natural Science Foundation of China; China Postdoctoral Science Foundation; International Postdoctoral Exchange Fellowship Program; et al. (Elsevier BV, 2020-11)
    The Maillard reaction in the aqueous system with and without ultrasound treatment was used to prepare conjugates between soy protein isolate (SPI) and citrus pectin (CP)/apple pectin (AP). Ultrasound treatment at a power of 450 W and a temperature of 70 °C significantly accelerated the conjugation processes between SPI and pectin samples and led to much greater grafting extents compared to the traditional wet heating. A higher degree of graft of the SPI-CP conjugates was achieved at a shorter ultrasound duration compared to the SPI-AP conjugates, possibly attributed to the larger molecular weight and the more flexible structure of AP. SDS-PAGE analysis confirmed the formation of SPI-pectin conjugates. Analysis of the protein secondary and tertiary structures suggested that the attachment of CP or AP changed the spatial conformation of SPI and led to a looser protein structure. In addition to the grafting process, ultrasound was also observed to play a marked role in unfolding the SPI resulting in more favorable structures for the Maillard reaction. Furthermore, the application of ultrasound to the conjugation process significantly increased the surface hydrophobicity and emulsifying properties of both conjugates, indicating that ultrasound can be a desirable method for protein-polysaccharide conjugation.
  • The effect of bovine feeding system (pasture or concentrate) on the oxidative and sensory shelf life of whole milk powder

    Clarke, H. J.; Griffin, Carol; Hennessy, D.; O'Callaghan, T. F.; O'Sullivan, M. G.; Kerry, J. P.; Kilcawley, Kieran (2021)
  • Breakage of infant milk formula through three different processing methods and its influence on powder properties

    Han, Jie; Fitzpatrick, John; Cronin, Kevin; Maidannyk, Valentyn; Miao, Song; Teagasc Walsh Fellowship Programme (Elsevier BV, 2020-10)
    Dairy powder breakage has always occurred during production and transportation though few studies on it have been published. This paper examines the breakage of infant formula using three different processing methods (laboratory high-speed mixing, lab-scale pneumatic conveying, and factory-scale blending) and the effect of breakage on powder properties. In both mixing and high-velocity pneumatic conveying, particles were broken into smaller entities and the particle size of samples significantly decreased. Particle breakage was accompanied by a significant decrease in porosity and increase in density and surface free fat. This in-turn decreased the rehydration properties of samples, especially for high-speed mixing, while breakage had only a small influence on powder flowability. By contrast, some agglomeration occurred during blending for short time in the blender and the particle size did not decrease (P > 0.05) even for blending at longer time, thus, there were only minor impacts on physical and functional properties of powders.
  • A Systems-Wide Analysis of Proteolytic and Lipolytic Pathways Uncovers The Flavor-Forming Potential of The Gram-Positive Bacterium Macrococcus caseolyticus subsp. caseolyticus

    Mazhar, Shahneela; Kilcawley, Kieran; Hill, Colin; McAuliffe, Olivia; Teagasc Walsh Fellowship Program; 2015055 (Frontiers Media SA, 2020-07-07)
    Macrococcus caseolyticus subsp. caseolyticus is a Gram-positive, commensal organism documented to be present as a component of the secondary microflora in fermented foods such as Ragusano and Fontina cheeses and Cantonese sausage. In these products, the organism appears to play a role in ripening and the development of the final organoleptic qualities. However, the role of this organism in flavor generation is not well understood. Therefore, the objective of this study was to investigate the role of M. caseolyticus subsp. caseolyticus in flavor compound formation through an examination of enzymatic, metabolomic and genomic data. A bank of M. caseolyticus subsp. caseolyticus strains derived from a variety of niches were examined. Enzyme activities analyzed comprised those of the proteolytic and lipolytic cascades including cell-envelope proteinase (CEP), peptidases, esterases, lipases, aminotransferases and glutamate dehydrogenase (GDH). Strain to strain variation was observed, often associated with niche. All strains, except those isolated from non-dairy sources, demonstrated high CEP activity. Such high CEP activity associated with dairy strains implies the importance of this characteristic in the adaptation of these strains to a dairy-specific niche. However, limited downstream peptidolytic activity, in addition to a limited ability to generate free amino acids (FAA) was observed across all strains, indicating weak ability of this organism to generate amino-acid derived flavor compounds. Interestingly, the strains with high CEP activity also demonstrated high esterase activity and gas chromatography-mass spectrometry (GC-MS) analysis of the volatile compounds produced when these strains were grown in lactose-free milk demonstrated differences in the range and types of volatiles produced. In contrast to this metabolic versatility, comparative genome analysis revealed the distribution of components of the proteolytic and lipolytic system in these strains to be conserved. Overall, this study demonstrates the potential of M. caseolyticus subsp. caseolyticus to generate diverse volatile flavor compounds. Additionally, the identification of the highly active strain-specific cell wall bound caseolytic proteases deriving extensive casein hydrolysis, serves as a promising avenue which can be potentially harnessed in the future to produce greater and more diverse flavor compounds.
  • Lactolisterin BU, a Novel Class II Broad-Spectrum Bacteriocin from Lactococcus lactis subsp. lactis bv. diacetylactis BGBU1-4

    Lozo, Jelena; Mirkovic, Nemanja; O'Connor, Paula M.; Malesevic, Milka; Miljkovic, Marija; Polovic, Natalija; Jovcic, Branko; Cotter, Paul D.; Kojic, Milan; Ministry of Education, Science and Technological Development of the Republic of Serbia; et al. (American Society for Microbiology, 2017-10-17)
    Lactococcus lactis subsp. lactis bv. diacetylactis BGBU1-4 produces a novel bacteriocin, lactolisterin BU, with strong antimicrobial activity against many species of Gram-positive bacteria, including important food spoilage and foodborne pathogens, such as Listeria monocytogenes, Staphylococcus aureus, Bacillus spp., and streptococci. Lactolisterin BU was extracted from the cell surface of BGBU1-4 by 2-propanol and purified to homogeneity by C18 solid-phase extraction and reversed-phase high-performance liquid chromatography. The molecular mass of the purified lactolisterin BU was 5,160.94 Da, and an internal fragment, AVSWAWQH, as determined by N-terminal sequencing, showed low-level similarity to existing antimicrobial peptides. Curing and transformation experiments revealed the presence of a corresponding bacteriocin operon on the smallest plasmid, pBU6 (6.2 kb), of strain BGBU1-4. Analysis of the bacteriocin operon revealed a leaderless bacteriocin of 43 amino acids that exhibited similarity to bacteriocin BHT-B (63%) from Streptococcus ratti, a bacteriocin with analogy to aureocin A.

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