Application of hand-held near-infrared and Raman spectrometers in surface treatment authentication of cork stoppers

The aim of this paper was to evaluate the potential of using near-infrared (NIR) spectroscopy and multivariate analysis as a rapid tool to non-destructively determine the presence of surface treatments applied to cork stoppers. Density and dimensions of 6 closure varieties were characterized and the extraction force was measured on those produced for still wines. Cork stoppers were also analyzed using hand-held NIR and Raman spectrometers. Soft independent modelling of class analogy (SIMCA) models showed significant differences among treated and untreated samples, linked to components of the coating agents applied (silicone and paraffin). SIMCA model''s classification performance was tested and high sensitivity (93.33 %) and specificity (100 %) values were obtained. Partial least squares regression (PLSR) model accurately predicted the extraction forces measured with low standard error of prediction (SEP = 4.0 daN). Our results are promising for the future application of this technology in cork industry, reducing time and economic losses. © 2021 The Author(s

White wine processing by UHPH without SO2. Elimination of microbial populations and effect in oxidative enzymes, colloidal stability and sensory quality

The use of UHPH sterilization in the absence of SO2 has been used to eliminate wild microorganisms and inactivate oxidative enzymes. A white must of the Muscat of Alexandria grape variety was continuously processed by UHPH at 300 MPa (inlet temperature: 23–25 °C). The initial microbial load of the settled must was 4-log CFU/mL for both yeast and moulds, and slightly lower for bacteria. After UHPH processing, no microorganisms were detected in 1 mL. UHPH musts remain without fermentative activity for more than 60 days.Postprint (published version

An overview of the evolution of infrared spectroscopy applied to bacterial typing

The sustained emergence of new declared bacterial species makes typing a continuous challenge for microbiologists. Molecular biology techniques have a very significant role in the context of bacterial typing, but they are often very laborious, time consuming and eventually fail when dealing with very closely related species. Spectroscopic-based techniques appear in some situations as a viable alternative to molecular methods with advantages in terms of analysis time and cost. Infrared and mass spectrometry are among the most exploited techniques in this context: particularly, infrared spectroscopy emerged as a very promising method with multiple reported successful applications. This article presents a systematic review on infrared spectroscopy applications for bacterial typing, highlighting fundamental aspects of infrared spectroscopy, a detailed literature review (covering different taxonomic levels and bacterial species), advantages and limitations of the technique over molecular biology methods and a comparison with other competing spectroscopic techniques such as MALDI-TOF MS, Raman and intrinsic fluorescence. Infrared spectroscopy possesses a high potential for bacterial typing at distinct taxonomic levels and worthy of further developments and systematization. The development of databases appears fundamental towards the establishment of infrared spectroscopy as a viable method for bacterial typing.FCT -Fundação para a Ciência e a Tecnologia(PT2020 UID/QUI/50006/2013)info:eu-repo/semantics/publishedVersio

Behaviour of pathogenic gram negative bacteria inoculated in milk and model cheese treated with high hydrostatic pressure

Els efectes de les altes pressions hidrostàtiques i la capacitat per sobreviure, recuperar-se i créixer de tres microorganismes patògens (Yersinia enterocolitica, Escherichia coli Salmonella enterica) van ser investigats en llet desnatada i en un formatge model elaborat amb i sense estàrter. Les mostres inoculades amb aquests microorganismes, van ser tractades a 300, 400 i 500 MPa (exceptuant les mostres inoculades amb soques de S. enterica) durant 10 minuts a 20ºC o a temperatura ambient i van ser analitzades microbiològicament just després d'aplicar el tractament d'altes pressions i als 1, 2, 7, 10 i 15 dies (en el cas dels experiments fets amb llet desnatada) i 1, 7 i 15 dies después del tractament (en el cas de les mostres de formatge model) per estudiar l'evolució i comportament de la població d'aquests microorganismes durant el període de conservació. Les mostres de llet desnatada i de formatge model elaborades amb estàrter, van mostrar una letalitat màxima després de ser tractades a 400 i 500 MPa i no es van poder detectar diferències estadísticament significatives en el comportament baroresistent d'aquests microorganismes, exceptuant el cas de les soques de Y. enterocoliticaÉs important mencionar que les mostres de formatges elaborades sense estàrter van necessitar més pressió per obtenir les mateixes reduccions que en mostres de formatge produïdes amb estàrter. De fet, en aquest cas, el tractament més efectiu va ser 500 MPa per les soques d'E. coli i 400 MPa per les soques de S. enterica. Els patògens inoculats en formatge model produït amb estàrter no van tenir capacitat de recuperar-se i créixer: els recomptes de microorganismes en les mostres tractades van anar disminuint durant el període de conservació a 8 o 12ºC. En canvi, en el cas de la llet desnatada i del formatge model elaborat sense estàrter, totes les mostres tractades van mostrar una tendència a incrementar els seu recomptes cel·lulars durant el període de conservació. Aquests resultats suggereixen que la presència de l'estàrter i el baix pH són els principals factors per controlar la capacitat d'aquests microorganismes de recuperar-se i créixer en aquest tipus de formatge tractat per altes pressions hidrostàtiques.The effects of high hydrostatic pressure (HHP) treatment, and the ability for survival, repair and growth of three human pathogenic microorganisms (Yersinia enterocolitica, Escherichia coli and Salmonella enterica strains) were investigated in skimmed milk and model cheese made with and without starter culture. Inoculated samples were treated at 300, 400 and 500 MPa (except S. enterica) for 10 min at 20ºC or at room temperature and analysed at 1, 2, 4, 7, 10 and 15 days (in the case of skimmed milk samples) and at 0, 1, 7 and 15 days (in the case of model cheese samples) to study the behaviour of bacterial population over time. Skimmed milk and cheese samples produced with starter culture showed the maximum lethality at 400 and 500 MPa and no significant differences in the baroresistant behaviour of microorganisms were detected, except in the case of Y. enterocolitica strains. Nevertheless, it is important to remark that in cheese produced without starter culture, it was necessary to apply more pressure to obtain the same reduction than in cheese produced with starter culture. In fact, the most effective treatment was mainly 500 MPa, for E. coli strains and 400 MPa for S. enterica strains. Ability to repair and grow was not observed in model cheese produced with starter culture and cell counts of treated samples decreased after 15 days of storage at 8 or 12ºC. Whereas, in skimmed milk and cheese produced without starter, all pressurized samples showed the trend to repair and grow during the storage period. These results suggest that the presence of starter and low pH are the main factors to control the ability to recover and grow of Y. enterocolitica, E. coli and S. enterica strains inoculated in this type of cheese and treated by HHP

Determination of Nutrient Supplementation by Means of ATR-FTIR Spectroscopy during Wine Fermentation

Nitrogen is a limiting factor for the development of wine alcoholic fermentation. The addition of nutrients and different nitrogen sources is a usual practice for many winemakers. Currently, there is a market trend toward wine that is additive-free and there are also restrictions on the amount of ammonium fermentation agents that can be added to the wine. In this work, the changes produced on the alcoholic fermentation by the addition of different nitrogen sources were evaluated by the use of ATR-FTIR. The results showed the feasibility of this technique to observe differences in the growth yeast capacity depending on the type of the nutrients added. A high influence on the development of the alcoholic fermentation was observed, especially at its exponential and the stationary phases. Moreover, the changes observed in the recorded spectra were related to the proteins and lipid esters composition of the yeast cell wall. This technique should be a useful tool to evaluate nitrogen deficiencies during winemaking although further studies should be done in order to evaluate more influential factors

Linking Findings in Microfluidics to Membrane Emulsification Process Design: The Importance of Wettability and Component Interactions with Interfaces

In microfluidics and other microstructured devices, wettability changes, as a result of component interactions with the solid wall, can have dramatic effects. In emulsion separation and emulsification applications, the desired behavior can even be completely lost. Wettability changes also occur in one phase systems, but the effect is much more far-reaching when using two-phase systems. For microfluidic emulsification devices, this can be elegantly demonstrated and quantified for EDGE (Edge-base Droplet GEneration) devices that have a specific behavior that allows us to distinguish between surfactant and liquid interactions with the solid surface. Based on these findings, design rules can be defined for emulsification with any micro-structured emulsification device, such as direct and premix membrane emulsification. In general, it can be concluded that mostly surface interactions increase the contact angle toward 90°, either through the surfactant, or the oil that is used. This leads to poor process stability, and very limited pressure ranges at which small droplets can be made in microfluidic systems, and cross-flow membrane emulsification. In a limited number of cases, surface interactions can also lead to lower contact angles, thereby increasing the operational stability. This paper concludes with a guideline that can be used to come to the appropriate combination of membrane construction material (or any micro-structured device), surfactants and liquids, in combination with process conditions

Ultrafiltration of Black Soldier Fly (<i>Hermetia illucens</i>) and Mealworm (<i>Tenebrio molitor</i>) Protein Concentrates to Enhance Emulsifying and Foaming Properties

Mealworm, TM (Tenebrio molitor), and black soldier fly, BSF (Hermetia illucens) are of special interest for food and feed applications due to their environmental benefits such as low water and land requirements, low greenhouse gas emissions, and high feed-conversion efficiency. This study assesses the use of ultrafiltration (UF) to fractionate protein concentrates from TM and BSF (TMPC, BSFPC) in order to enhance emulsifying and foaming properties. A 30 kDa regenerated cellulose acetate membrane enabled the separation of concentrate and permeate fractions for both insect proteins from two different initial feed concentrations (10 and 7.5 g/L). Permeate flux and protein transmission behave differently depending on the insect type and the initial concentration; while for TMPC permeate flux increases with a decrease in the initial protein concentration, it is not affected for BSFPC. The existing membrane cleaning protocols are suitable for recovering water flux after UF of insect proteins, enabling membrane re-use. Emulsifying activity is maintained for all the TMPC fractions, but it is significantly lower for the permeate fractions of BSFPC. Foaming properties are maintained for all the UF fractions of BSFPC and the ones from 7.5 g/L TMPC. Acidic solubilization leads to a fraction with enhanced emulsifying capacity and one with higher foaming capacity than the original for BSFPC. This study opens the door to membrane technology for insect protein fractionation, which has not been studied so far and has already provided useful solutions for other animal and plant proteins

Polyphenol loaded w1/o/w2 emulsions stabilized with lesser mealworm (Alphitobius diaperinus) protein concentrate produced by membrane emulsification : Stability under simulated storage, process, and digestion conditions

Water-in-oil-in-water (W1/O/W2 ) emulsions are complex delivery systems for polyphe-nols amongst other bio-actives. To stabilize the oil–water interphase, dairy proteins are commonly employed, which are ideally replaced by other, more sustainable sources, such as insect proteins. In this study, lesser mealworm (Alphitobius diaperinus) protein concentrate (LMPC) is assessed and compared to whey protein (WPI) and pea protein (PPI), to stabilize W1/O/W2 emulsions and encapsulate a commercial polyphenol. The results show that LMPC is able to stabilize W1/O/W2 emulsions comparably to whey protein and pea protein when using a low-energy membrane emulsification system. The final droplet size (d4,3) is 7.4 µm and encapsulation efficiency is between 72 and 74%, regardless of the protein used. Under acidic conditions, the LMPC shows a similar performance to whey protein and outperforms pea protein. Under alkaline conditions, the three proteins perform similarly, while the LMPC-stabilized emulsions are less able to withstand osmotic pressure differences. The LMPC stabilized emulsions are also more prone to droplet coalescence after a freeze–thaw cycle than the WPI-stabilized ones, but they are the most stable when exposed to the highest temperatures tested (90◦C). The results show LMPC’s ability to stabilize multiple emulsions and encapsulate a polyphenol, which opens the door for application in foods