Optimisation of blueberry (Vaccinium corymbosum L.) press residue extraction using a combination of pectolytic enzyme and ultrasound treatments

Blueberries are one of the most popular and widely consumed berries, they are usually consumed fresh, dried or processed into juice. During the production of juices large quantities of berry press residues are generated, which are an industrial by-product and they accumulate as food waste. Optimal management of this industrial fruit by-product could help in utilising berry press residues with the purpose to valorise and add economic value. Blueberry press residues consist of skins and seeds which hold valuable compounds with antioxidant activity –polyphenolics. To facilitate the objective of bioactive compound release, the cell walls must rupture. Pectolytic enzymes could be used to degrade the structural polysaccharides of the berry skin cell wall, thus releasing the contents of the cells into the extraction medium. The physical characteristics of berry skins allows the use of pectolytic enzymes for the disruption of cells; however, the effects of enzymatic hydrolysis could be further improved using ultrasound. In this study the combined effects of enzyme and ultrasonic treatments were evaluated and optimised using the Response Surface Methodology approach in order to increase the release of polyphenolic compounds (especially anthocyanins). The optimised method was further tested to evaluate the application potential of enzyme and ultrasound treatment to prepare blueberry or lingonberry juice with increased antioxidant activity and more vibrant colour. The obtained results provide an optional method of berry press residue valorisation to produce higher quality juice or extract bioactive compounds from this type of food-waste.

1H-NMR Metabolomics as a Tool for Winemaking Monitoring

The chemical composition of wine is known to be influenced by multiple factors including some viticulture practices and winemaking processes. 1H-NMR metabolomics has been successfully applied to the study of wine authenticity. In the present study, 1H-NMR metabolomics in combination with multivariate analysis was applied to investigate the effects of grape maturity and enzyme and fining treatments on Cabernet Sauvignon wines. A total of forty wine metabolites were quantified. Three different stages of maturity were studied (under-maturity, maturity and over-maturity). Enzyme treatments were carried out using two pectolytic enzymes (E1 and E2). Finally, two proteinaceous fining treatments were compared (vegetable protein, fining F1; pea protein and PVPP, fining F2). The results show a clear difference between the three stages of maturity, with an impact on different classes of metabolites including amino acids, organic acids, sugars, phenolic compounds, alcohols and esters. A clear separation between enzymes E1 and E2 was observed. Both fining agents had a significant effect on metabolite concentrations. The results demonstrate that 1H-NMR metabolomics provides a fast and robust approach to study the effect of winemaking processes on wine metabolites. These results support the interest to pursue the development of 1H-NMR metabolomics to investigate the effects of winemaking on wine quality.

Application of crude pectolytic enzymes from Saccaharomyces cerevisiae (ATCC 52,712) to starch extraction in Ghana: effects of enzyme technology on pasting characteristics in different cassava varieties

Previous work on enzyme application to starch extraction enhanced yield and starch recovery rates as well as modified some physicochemical properties of starches for potential alternative application to industry. The response of the technology, however, showed some sensitivity to variety. The knowledge gap therefore was to establish whether such physicochemical responses (by the technology) to variety affects the pasting parameters of the starches extracted. The pasting parameters of starches extracted from four different cassava varieties (‘Nkabom’, ‘Afisiafi’, ‘Bankyehemaa’ and ‘Esambankye’), with the aid of crude pectolytic enzymes from the Saccharomyces cerevisiae (ATCC 52,712), were investigated. Although a general response pattern was observed for most of the pasting parameters measured, which includes general enhancements (P < 0.05) in starch gelatinization viscosity, with improvements in gelatinization time and temperature and peak viscosities in most of the varieties, there were significant differences (P < 0.05) in their respective peak time and temperature requirements for the attainment of peak viscosity. Values for the breakdown viscosity were also generally increased (P < 0.05). The technology also increased values for setback viscosity in both the ‘Nkabom’ and ‘Bankyehemaa’ varieties but reduced setback values in the ‘Afisiafi’ and ‘Esambankye’ varieties. As pasting properties are one of the most important characteristics of starch that determine its overall utility, knowledge from this study should inform how adoption of the technology would help diversify the various cassava varieties for appropriate domestic and industrial applications while harnessing its benefits of improved starch yield.

Erwinia carotovora Quorum Sensing System Regulates Host-Specific Virulence Factors and Development Delay in Drosophila melanogaster

ABSTRACT Multihost bacteria have to rapidly adapt to drastic environmental changes, relying on a fine integration of multiple stimuli for an optimal genetic response. Erwinia carotovora spp. are phytopathogens that cause soft-rot disease. Strain Ecc15 in particular is a model for bacterial oral-route infection in Drosophila melanogaster as it harbors a unique gene, evf, that encodes the Erwinia virulence factor (Evf), which is a major determinant for infection of the D. melanogaster gut. However, the factors involved in the regulation of evf expression are poorly understood. We investigated whether evf could be controlled by quorum sensing as, in the Erwinia genus, quorum sensing regulates pectolytic enzymes, the major virulence factors needed to infect plants. Here, we show that transcription of evf is positively regulated by quorum sensing in Ecc15 via acyl-homoserine lactone (AHL) signal synthase ExpI and AHL receptors ExpR1 and ExpR2. We also show that the load of Ecc15 in the gut depends upon the quorum sensing-mediated regulation of evf. Furthermore, we demonstrate that larvae infected with Ecc15 suffer a developmental delay as a direct consequence of the regulation of evf via quorum sensing. Finally, we demonstrate that evf is coexpressed with plant cell wall-degrading enzymes (PCWDE) during plant infection in a quorum sensing-dependent manner. Overall, our results show that Ecc15 relies on quorum sensing to control production of both pectolytic enzymes and Evf. This regulation influences the interaction of Ecc15 with its two known hosts, indicating that quorum sensing signaling may impact bacterial dissemination via insect vectors that feed on rotting plants. IMPORTANCE Integration of genetic networks allows bacteria to rapidly adapt to changing environments. This is particularly important in bacteria that interact with multiple hosts. Erwinia carotovora is a plant pathogen that uses Drosophila melanogaster as a vector. To interact with these two hosts, Ecc15 uses different sets of virulence factors: plant cell wall-degrading enzymes to infect plants and the Erwinia virulence factor (evf) to infect Drosophila. Our work shows that, despite the virulence factors being specific for each host, both sets are coactivated by homoserine lactone quorum sensing and by the two-component GacS/A system in infected plants. This regulation is essential for Ecc15 loads in the gut of Drosophila and minimizes the developmental delay caused by the bacteria with respect to the insect vector. Our findings provide evidence that coactivation of the host-specific factors in the plant may function as a predictive mechanism to maximize the probability of transit of the bacteria between hosts.

Study of the influence of endopolyga-lacturonase Kluyveromyces marxianus yeast species on the processes of clarification and quality of brandy wine materials and distillates

В работе представлены результаты исследований влияния эндополигалактуроназы дрожжей рода Kluyveromyces marxianus на процессы отделения и осветления сусла, а также качество коньячных виноматериалов и дистиллятов. Проблемой виноделия является высокое содержание полисахаридов в виноградной ягоде, что снижает выход сусла, затрудняет процессы его осветления, способствует окислению и обогащению нежелательными компонентами, ухудшающими качество готового продукта. Использование ферментных препаратов пектолитического действия в коньячном производстве ограничено из-за риска увеличения содержания метанола, который образуется при действии на пектины винограда пектинэстеразы. Перспективным направлением является использование в коньячном производстве эндополигалактуроназы, продуцируемой дрожжами вида Kluyveromyces marxianus . Установлено, что обработка сусла и мезги опытным ферментным препаратом, полученном при культивировании штамма дрожжей вида Kluyveromyces marxianus , способствует увеличению выхода сусла, снижению содержания взвесей и объема образующегося осадка при осветлении сусла, повышению его качества. Показано, что физико-химический состав виноматериалов и дистиллятов, полученных из обработанного сусла, практически не изменяется. Массовая концентрация метанола в опытных коньячных виноматериалах и дистиллятах не превышала уровня контрольных образцов. Установлена эффективность использования препарата в коньячном производстве с целью повышения выхода и качества сусла. The article presents the results of study on the influence of endopolygalacturonase yeast species Kluyveromyces marxianus on the processes of separation and clarification of must, as well as the quality of brandy wine materials and distillates. The problem of winemaking is the high content of polysaccharides in grape berries, which reduces the yield of must, complicates the process of clarification, contributes to the oxidation and enrichment with undesirable components degrading the quality of the finished product. Use of pectolytic enzymes in brandy production is limited due to the risk of increase in the content of methanol, appearing when pectin esterase acts on grape pectins. Use of endopoligalacturonase rendered by the yeast species Kluyveromyces marxianus is a promising direction in brandy production. It was found that treatment of the must and pulp with experimental enzyme preparation obtained by culturing a yeast strain of the species Kluyveromyces marxianus contributes to an increase in the yield of the must and a decrease in the content of suspensions and volume of the sediment formed in the process of must clarification, and quality improving. It was shown that the physicochemical composition of wine materials and distillates obtained from the treated must remained permanent. Mass concentration of methanol in the experimental brandy wine materials and distillates did not exceed the level of control samples. The effectiveness of use of the preparation in brandy production was established in order to increase the product yield and quality of the must.

The effect of commercial pectolytic enzymes on young Babić wines quality

The purpose of this research was to determine the effect of commercial pectolytic enzymes on the anthocyanin composition, colour parameters and specific sensory atributes in young wines produced of Croatian autochthonous variety Babić. The maceration without commercial enzymes was compared with two different enzymes: pectinase with additional cellulase and hemicellulase activity (A) and the pectinase with inactive yeast cells (B), during two harvests. Both products had a positive effect on the anthocyanin content and composition, but with different intensities. The influence of enzymes was confirmed through the colour parameters; intensity, hue and the ratio between yellow, red and blue, depending on product. Young wines produced with pectinase enzyme were significantly better, for all parameters. The sensory analysis showed that wines produced with pectinase enzyme (product A) were significantly better than those produced without enzymes. The combination of pectolytic enzymes and inactive yeast cells (product B) had a partial positive effect on the anthocyanins, colour parameters and sensory quality during two harvests. The use of specific commercial pectolytic enzymes can be a good and beneficial technological treatment in production of Babić young wine, based on preliminary research. These data confirmed the need to carry out research prior to use in real production, to select and recommend certain commercial enzyme products, according to the particular grape variety and certain wine properties that want to be improved.

Pulsed Electric Field Processing of Red Grapes (cv. Rondinella): Modifications of Phenolic Fraction and Effects on Wine Evolution

Pulsed electric field (PEF) is a non-thermal technology able to promote color and polyphenols extraction from grape skins. Most of the publications about PEF in winemaking report data concerning international varieties, poorly considering minor cultivars and the medium/long-term effects of the treatment on wine composition during storage. PEF was applied at different specific energies (2, 10, and 20 kJ kg−1) on grapes of the low-color red cv. Rondinella, after crushing-destemming. Pressing yield, the evolution of color, and total phenolic index (TPI) were measured during skin maceration. Moreover, the wines were characterized for basic compositional parameters, color, anthocyanin profile, phenolic composition (glories indices), metal content (Fe, Cr, and Ni), and sensory characters, two and twelve months after the processing, in comparison with untreated samples and pectolytic enzymes (PE). PEF did not affect fermentation evolution, nor did it modify wine basic composition or metal content. Treatments at 10 and 20 kJ kg−1 led to higher color and TPI in wines, in comparison to PE, because of increased content of anthocyanins and tannins. The sensory evaluation confirmed these findings. Modifications remained stable in wines after twelve months. Glories indices and vitisin A content highlighted greater potential stability of wine color in PEF-treated wines.

Quorum sensing regulation in Erwinia carotovora affects development of Drosophila melanogaster infected larvae

Multi-host bacteria must rapidly adapt to drastic environmental changes, relying on integration of multiple stimuli for an optimal genetic response. Erwinia spp. are phytopathogens that cause soft-rot disease in plants. Erwinia carotovora Ecc15 is used as a model for bacterial oral-route infection in Drosophila melanogaster as it harbors a gene, the Erwinia virulence factor (Evf), which has been previously shown to be a major determinant for infection of D. melanogaster gut. However, the factors involved in regulation of evf expression are poorly understood. We investigated whether evf could be controlled by quorum sensing since, in the Erwinia genus, quorum sensing regulates pectolytic enzymes, the major virulence factors needed to infect plants. Here, we show that transcription of evf is positively regulated by quorum sensing in Ecc15 via the acyl-homoserine lactone (AHL) signal synthase ExpI, and the AHL receptors ExpR1 and ExpR2. Moreover, we demonstrate that the GacS/A two-component system is partially required for evf expression. We also show that the load of Ecc15 in the gut depends upon the quorum sensing-mediated regulation of evf. Furthermore, we demonstrate that larvae infected with Ecc15 suffer a developmental delay as a direct consequence of the regulation of evf via quorum sensing. Overall, our results show that Ecc15 relies on quorum sensing to control production of both pectolytic enzymes and Evf. This regulation influences the interaction of Ecc15 with its two known hosts, indicating that quorum sensing and GacS/A signaling systems may impact bacterial dissemination via insect vectors that feed on rotting plants.SignificanceIntegration of genetic networks allows bacteria to rapidly adapt to changing environments. This is particularly important in bacteria that interact with multiple hosts. Erwinia carotovora Ecc15 is a plant pathogen that uses Drosophila melanogaster as a vector. To interact with these two hosts, Ecc15 uses two different sets of virulence factors: plant cell wall-degrading enzymes to infect plants and the Erwinia virulence factor (evf) to infect Drosophila. Our work shows that, despite the virulence factors being different, both are regulated by homoserine lactone quorum sensing and the two component GacS/A system. Moreover, we show that these pathways are essential for Ecc15 loads in the gut of Drosophila and that this interaction carries a cost to the vector in the form of a developmental delay. Our findings provide evidence for the importance of quorum sensing regulation in the establishment of multi-host interactions.