Kieran M. Lynch

Genomics of Weissella cibaria with an examination of its metabolic traits.

Weissella is a genus of lactic acid bacteria (LAB) consisting of species formerly included in the Leuconostoc paramesenteroides group. Similar to other LAB, they are commonly found in fermented foods but have also been isolated from environmental and human samples. Currently there are 20 recognized species. Herein, three Weissella cibaria genomes were sequenced using Illumia Mi-Seq and Roche 454 technologies. Annotation was performed using the Prokka and JGI IMG pipelines. A thorough analysis of the genomics of the W. cibaria strains was performed, in addition to brief comparative analyses of the genus Weissella as a whole. Genomic sequence data from the newly sequenced W. cibaria strains and data available in GenBank for other Weissella strains was used (n = 10; four Weissella cibaria, one Weissella ceti, one Weissella confusa, one Weissella halotolerans, two Weissella koreensis and one Weissella paramesenteroides). The genomes had sizes varying from 1.3 to 2.4 Mb. DNA G+C contents ranged from 35 to 45 mol%. The core- and pan-proteome at genus and species levels were determined. The genus pan-proteome was found to comprise 4712 proteins. Analysis of the four W. cibaria genomes indicated that the core-proteome, consisting of 729 proteins, constitutes 69 % of the species pan-proteome. This large core-set may explain the divergent niches in which this species has been found. In W. cibaria, in addition to a number of phosphotransferase systems conferring the ability to assimilate plant-associated polysaccharides, an extensive proteolytic system was identified.

Starch Characteristics Linked to Gluten-Free Products

The increasing prevalence of coeliac disease (CD) and gluten-related disorders has led to increasing consumer demand for gluten-free products with quality characteristics similar to wheat bread. The replacement of gluten in cereal-based products remains a challenge for scientists, due to its unique role in network formation, which entraps air bubbles. When gluten is removed from a flour, starch is the main component left. Starch is used as gelling, thickening, adhesion, moisture-retention, stabilizing, film forming, texturizing and anti-staling ingredient. The extent of these properties varies depending on the starch source. The starches can additionally be modified increasing or decreasing certain properties of the starch, depending on the application. Starch plays an important role in the formulation of bakery products and has an even more important role in gluten-free products. In gluten-free products, starch is incorporated into the food formulation to improve baking characteristics such as the specific volume, colour and crumb structure and texture. This review covers a number of topics relating to starch; including; an overview of common and lesser researched starches; chemical composition; morphology; digestibility; functionality and methods of modification. The emphasis of this review is on starch and its properties with respect to the quality of gluten-free products.

Exopolysaccharide producing lactic acid bacteria: Their techno-functional role and potential application in gluten-free bread products

Exopolysaccharides produced by lactic acid bacteria are typically high molecular weight polymers that display physiochemical properties similar to commercial hydrocolloids or gums i.e. ability to form a network and bind water. Such properties, coupled with their production in-situ, mean these exopolysaccharides represent a natural alternative to commercial hydrocolloids for the enhancement of both gluten-containing and gluten-free cereal products. Research in the past decade has shown the potential of these lactic acid bacteria exopolysaccharides, in combination with sourdough technology, to enhance the quality of gluten-containing (primarily wheat) products, particularly with respect to loaf volume, shelf-life and staling rate. Such techno-functional properties can be exploited in the gluten-free area and shows promise in helping to overcome the challenge of producing gluten-free products of the same quality and acceptability as their gluten-containing counterparts. The aim of this review is to present an overview of our current knowledge of exopolysaccharides produced by lactic acid bacteria, and how they can be exploited in the area of cereal science and gluten-free.

Lactic Acid Bacteria Exopolysaccharides in Foods and Beverages: Isolation, Properties, Characterization, and Health Benefits

Exopolysaccharides produced by lactic acid bacteria are a diverse group of polysaccharides produced by many species. They vary widely in their molecular, compositional, and structural characteristics, including mechanisms of synthesis. The physiochemical properties of these polymers mean that they can be exploited for the sensorial and textural enhancement of a variety of food and beverage products. Traditionally, lactic acid bacteria exopolysaccharides have an important role in fermented dairy products and more recently are being applied for the improvement of bakery products. The health benefits that are continually being associated with these polysaccharides enable the development of dual function, added-value, and clean-label products. To fully exploit and understand the functionality of these exopolysaccharides, their isolation, purification, and thorough characterization are of great importance. This review considers each of the above factors and presents the current knowledge on the importance of lactic acid bacteria exopolysaccharides in the food and beverage industry.

Effect of salt reduction on wheat-dough properties and quality characteristics of puff pastry with full and reduced fat content

Puff pastry is a major contributor of fat and sodium intake in many countries. The objective of this research was to determine the impact of salt (0-8.4g/100g flour) on the structure and quality characteristics of puff pastry with full and reduced (-40%) fat content as well as the rheological properties of the resulting dough. Therefore, empirical rheological tests were carried out including dough extensibility, dough stickiness and GlutoPeak test. The quality of the puff pastry was characterized with the VolScan, Texture Analyzer and C-Cell. NaCl reduction significantly changed rheological properties of the basic dough as well as a number of major quality characteristics of the puff pastry. Significant differences due to NaCl addition were found in particular for dough resistance, dough stickiness, Peak Maximum Time and Maximum Torque (p<0.05). Peak firmness and total firmness decreased significantly (p<0.05) with increasing salt levels for puff pastry containing full fat. Likewise, maximal lift, specific volume, number of cells and slice brightness increased with increasing NaCl at both fat levels. Although a sensorial comparison of puff pastries revealed that salt reduction (30%) was perceptible, no significant differences were found for all other investigated attributes. Nevertheless, a reduction of 30% salt and 40% fat in puff pastry is achievable as neither the perception and visual impression nor attributes such as volume, firmness and flavour of the final products were significantly affected.

Development of novel quinoa-based yoghurt fermented with dextran producer Weissella cibaria MG1

The aim of this study was to develop a novel beverage fermented with Weissella cibaria MG1 based on aqueous extracts of wholemeal quinoa flour. The protein digestibility of quinoa based-milk was improved by applying complex proteolytic enzymes able to increase protein solubility by 54.58%. The growth and fermentation characteristics of Weissella cibaria MG1, including EPS production at the end of fermentation, were investigated. Fermented wholemeal quinoa milk using MG1 showed high viable cell counts (>109cfu/ml), a pH of 5.16, and significantly higher water holding capacity (WHC, 100%), viscosity (0.57mPas) and exopolysaccharide (EPS) amount (40mg/l) than the chemical acidified control. High EPS (dextran) concentration in quinoa milk caused earlier aggregation because more EPS occupy more space, and the chenopodin were forced to interact with each other. Microstructure observation indicated that the network structures of EPS-protein improve the texture of fermented quinoa milk. Overall, Weissella cibaria MG1 showed satisfactory technology properties and great potential for further possible application in the development of high viscosity fermented quinoa milk.

Novel approaches for Chemical and Microbiological shelf life extension of cereal crops

Abstract Economic losses due to post-harvest fungal spoilage and mycotoxin contamination of cereal crops is a frequently encountered issue. Typically, chemical preservatives are used to reduce the initial microbial load and the environmental conditions during storage are controlled to prevent microbial growth. However, in recent years the consumers’ desire for more naturally produced foods containing less chemical preservatives has grown increasingly stronger. This article reviews the latest advances in terms of novel approaches for chemical decontamination, namely application cold atmospheric pressure plasma and electrolyzed water, and their suitability for preservation of stored cereal crops. In addition, the alternative use of bio-preservatives, such as starter cultures or purified antimicrobial compounds, to prevent the growth of spoilage organisms or remove in-field accumulated mycotoxins is evaluated. All treatments assessed here show potential for inhibition of microbial spoilage. However, each method encounters draw-backs, making industrial application difficult. Even under optimized processing conditions, it is unlikely that one single treatment can reduce the natural microbial load sufficiently. It is evident that future research needs to examine the combined application of several treatments to exploit their synergistic properties. This would enable sufficient reduction in the microbial load and ensure microbiological safety of cereal crops during long-term storage.

Control of Zymoseptoria tritici cause of septoria tritici blotch of wheat using antifungal Lactobacillus strains.

This study explored an effective biological control agent based on lactic acid bacteria culture or culture supernatant, which was effective against fungicide‐resistant Zymoseptoria tritici, which causes septoria tritici blotch (STB).

Polyol-producing lactic acid bacteria isolated from sourdough and their application to reduce sugar in a quinoa-based milk substitute

The interest for plant-based dairy substitutes is expanding rapidly and consumers are opting for nutritious and healthy dairy alternatives. The reduction of sugar using different exogenous enzymes in combination with lactic acid fermentation in a quinoa-based milk substitute was explored in this study. Different amylolytic enzymes were used to release sugar from the raw material, which were further metabolised to mannitol, due to fermentation with two heterofermentative lactic acid bacteria. Using these two biotechnological techniques enables the reduction of sugar, while also preserving some of the sweetness. Leuconostoc citreum TR116, and Lactobacillus brevis TR055 were isolated from sourdough. Both strains showed high viable cell counts with L. citreum TR116 > 8.4 and L. brevis TR055 > 9.3 log cfu/mL, and a reduction in pH to 3.7 and 3.5 respectively. When fructose was available, mannitol was produced in conjunction with acetic acid in addition to lactic acid. Due to these processes, the original glucose value was reduced from 50 mmol/100 g to approximately 30 mmol/100 g, which equates to a glucose reduction of 40%. In respect to mannitol production, both strains performed well: L. citreum TR116 showed a conversion factor of 1:1 from fructose to mannitol, while L. brevis TR055 showed a lower yield, with a conversion factor of 1:0.8. Glycaemic load was reduced by more than a third, bringing it down to the low range with a value of about 10. Overall, enzymatic modification in conjunction with mannitol-producing lactic acid bacteria shows great potential for further possible application in the development of nutritious and sugar reduced plant-based milk substitutes.

Improvement of taste and shelf life of yeasted low-salt bread containing functional sourdoughs using Lactobacillus amylovorus DSM 19280 and Weisella cibaria MG1

The challenge remains for the baking industry to reduce salt levels in yeasted bread as directed by governments, retailers and consumers around the world. The two main problems associated with the reduction of salt are a lack of salty taste and the reduction in shelf-life. Both of these issues are addressed in the presented work. A range of breads containing different levels of salt (0.0%, 0.3% and 1.2% of NaCl) in combination with various levels of sourdough (0%, 6%, 12%, 18%, 24%) was produced. The different doughs were analysed for their rheological behaviour. The bread quality characteristics such as loaf volume, crumb structure, staling rate and microbial shelf life were also determined. The sourdoughs were analysed for their different metabolites: organic acids, sugars, exopolysaccharides (EPS), and antifungal compounds. A trained sensory panel was used to perform descriptive analysis of the bread samples. The object of this paper is to use functional sourdoughs, containing Lactobacillus amylovorus DSM 19280 and Weisella cibaria MG1 to compensate for the quality problems that occur when salt is reduced in yeasted bread. The application of functional sourdoughs containing exopolysaccharides and/or antifungal substances in salt reduced breads significantly improved the quality. The application of functional sourdoughs allows the reduction of salt to a level of 0.3%.