Concentration of aroma compounds from an industrial solution of soluble coffee by pervaporation process

Nonconventional yeasts to produce aroma compounds by using agri-food waste materials

Nowadays, biotechnological applications are emphasized to ensure sustainable development by reutilizing waste materials to prevent ecological problems and to produce or recover compounds that may have positive effects on health. Yeasts are fascinating microorganisms that play a key role in several traditional and innovative processes. Although Saccharomyces is the most important genus of yeasts, and they are major producers of biotechnological products worldwide, a variety of other yeast genera and species than Saccharomyces that are called 'non-Saccharomyces' or 'nonconventional' yeasts also have important potential for use in biotechnological applications. Some of the nonconventional yeast strains offer a unique potential for biotechnological applications to produce valuable secondary metabolites due to their characteristics of surviving and growing in such extreme conditions, e.g. wide substrate range, rapid growth, thermotolerance, etc. In this review, we aimed to summarize potential biotechnological applications of some nonconventional yeasts (Kluyveromyces spp., Yarrowia spp., Pichia spp., Candida spp., etc.) to produce industrially important aroma compounds (phenylethyl alcohol, phenylethyl acetate, isobutyl acetate, diacetyl, etc.) by reutilizing agri-food waste materials in order to prevent ecological problems and to produce or recover compounds that may have positive effects on health.

Modulation of aroma release of instant coffees through microparticles of roasted coffee oil

We report, on the successful addition of spray-dried microparticles containing roasted coffee oil, to soluble coffee (SC) and instant cappuccino (IC), to increase and tailor aroma release. Using PTR-ToF-MS (Proton Transfer Reaction Time-of-Flight Mass Spectrometry), five parameters were defined from time series intensity for each VOC, to compare the performance of different products: total area under the curve (AUC), area under the curve of burst (AUC-burst), maximum signal intensity, final intensity (5 min), and ratio AUC-burst/AUC. Microparticles with higher loads of roasted coffee oil were effective in increasing aroma intensity in SC while, for IC, all loads of microparticles improved aroma intensity. Volatility drove the VOC release in SC, and volatility and polarity for IC. Most compounds reached maximum headspace concentration in < 16 s upon start of reconstitution. These results open new perspectives for the development of instant coffee products and demonstrate their unique aroma release characteristics.

Membrane-Based Operations in the Fruit Juice Processing Industry: A Review

The fruit juice industry is one of the food sectors that has invested the most in the implementation of new technologies, such as non-thermal technologies. Among them, membrane processes are considered today well-established separation techniques to support the production and marketing of innovative fruit juices designed to exploit the sensory characteristics and nutritional peculiarities of fresh fruits. Pressure-driven membrane operations, membrane distillation, osmotic distillation and pervaporation have been widely investigated in the last few decades to replace conventional technologies used in fruit juice processing industry (i.e., clarification, stabilization, concentration and recovery of aroma compounds). This paper will review the significant progresses on the use of membrane-based operations in fruit juice processing industry in the light of the growing interest towards products with improved safety, quality and nutritional value and sustainable processes characterized by low energy consumption and low environmental impact.

Novel experimental approach to study aroma release upon reconstitution of instant coffee products

This study presents an experimental approach to study the kinetics and fast release of volatile organic compounds (VOCs) upon reconstitution of instant coffee products. A sampling setup coupled to PTR-ToF-MS (Proton Transfer Reaction Time-of-Flight Mass Spectrometry) for the automated and reproducible reconstitution of instant coffee products was developed to monitor the dynamic release of VOCs. A rapid release of aroma compounds was observed in the first seconds upon hot water addition ("aroma burst"), followed by subsequent decrease in headspace (HS) intensities over the course of analysis. Differences in time-intensity release profiles of individual VOCs were correlated to their Henry's Law constant, vapor pressure and water solubility. The setup and approach proposed here have shown to be sensitive and to respond to fast dynamic changes in aroma release. It allows studying VOCs release upon reconstitution and supports the development of novel technologies and formulations for instant products with improved aroma release properties.

Volatile and sensory analysis to discriminate meat from lambs fed different concentrate-based diets

Context Diet is one the most important pre-slaughter factors that potentially influences meat quality, but its effect on flavour quality remains equivocal. Aim The aim of the present study was to investigate the effect of diet composition on the flavour and sensory quality of meat from Texel × Scottish Blackface ram lambs. Methods Groups of 11 lambs were assigned to one of the following four dietary treatments for 54 days before slaughter: a concentrate containing barley, maize and soybean (C treatment); C supplemented with a saturated fat source (Megalac®); C supplemented with protected linseed oil; a by-product-based diet containing citrus pulp, distillers grain and soybean. Samples of cooked M. longissimus thoracis et lumborum were subjected to volatile analysis involving solid-phase microextraction followed by gas chromatography–mass spectrometry and to sensory analysis performed by a trained panel. Key results Univariate analysis of volatile data and sensory data showed few differences due to dietary treatments. However, multivariate analysis of the volatile data, and to a lesser extent the sensory profile data, showed potential to discriminate between lamb meat samples, on the basis of the different dietary treatments. Conclusions The inclusion of certain dietary ingredients in the diets of lambs to enhance the nutritional profile of lamb meat (through increasing n-3 fatty acid content) or to reduce feed-formulation costs (through the use of by-products) has minor effects on sensory quality but permits some discrimination between dietary treatments following the application of multivariate analysis. Implications The application of the findings is in allowing lamb producers to use alternative feed types without affecting the sensory quality of lamb negatively, but with the potential to discriminate lamb meat on the basis of its dietary background.

Aldehydes as Wort Off-Flavours in Alcohol-Free Beers—Origin and Control

Although present in concentrations in microgrammes per litre level, aldehydes, in particular those derived from Strecker degradation, are known to majorly contribute to the undesired wort flavour of alcohol-free beers. In order to improve currently available products, one needs to understand the underlying cause for the over-prevalence and identify leverage points and methods to selectively reduce the aldehydes in alcohol-free beers. This work gives a short overview on relevant flavour-active wort flavours identified in alcohol-free beer and on their involved chemical formation pathways. Consequently, aldehyde removal technologies in general and in brewing industry are presented. Adsorptive removal of off-flavours by aldehyde-scavenging groups is already widely exploited in the packaging industry and may achieve reduction of these components to near depletion, depending on the process conditions. Its principles are adaptable to recovering off-flavours before filling. Also, supercritical CO2 extraction has been successfully applied to separate flavours from food matrices. In brewing, the focus has been set to biologic conversion by restricted fermentation steps, but the reduction of key components of more than 70% is not achieved. Newer developments focus on thermal separation techniques that not only include non-specific physical dealcoholisation but also more selective technologies such as pervaporation, where aldehydes are reduced to near depletion. However, for most unit operations, selectivity and capacity are not yet investigated. Future research should explore the shortcomings of current techniques and overcome bottlenecks either by developing more specific methods for aldehyde removal and/or a clever combination of unit operations to optimise the separation and process integration.

Concentration of natural aroma compounds from fruit juice hydrolates by pervaporation in laboratory and semi-technical scale. Part 1. Base study

The first article of a two-article series presents pervaporation (PV) of volatile aroma compounds from fruit juice hydrolates (plum, apple, blackcurrant and cherry). The purpose of this research was to evaluate the effectiveness of fruit juice hydrolates separation on a laboratory scale (inert gas flow pervaporation system) and semi-technical (vacuum pervaporation system) by means of pervaporation. To create precise matrices for hydrolates before and after pervaporation for each of the separated systems, solid phase microextraction (SPME) technique and the gas chromatography-mass spectrometry (GC-MS) was applied. Sensory analysis confirmed improvement of aroma note of concentrated permeates as compared to feed hydrolates solutions. The results indicated that pervaporation may be applied in condensing aromatic water or fruit juice hydrolate, which may significantly enhance product quality and lengthen shelf life.

Sulfonic Membrane Sorption and Permeation Properties: Complementary Approaches to Select a Membrane for Pervaporation

In this contribution, the physical and chemical properties of the dense sulfonic membrane IonClad R4010 in the lithium form were studied to evaluate its potential application in pervaporation. To develop new membrane materials, it is necessary to know the influence of the membrane structure on the membrane equilibrium and transport properties. For this purpose, the sorption and permeation measurements of water and methanol in the liquid and vapor states were performed and correlated to the ion pairs/solvent interactions analyzed by the infrared spectroscopy. The IonClad R4010 equilibrium and transport properties were found to be quite different depending on the permeant nature. The sorption and diffusion behavior of water and methanol was well described by means of the type II sorption model (BET theory). The swelling capacity of the IonClad R4010 membrane in methanol was found to be much lower than that in liquid water. In contrast to methanol, the total dissociation of the ion pairs in the IonClad R4010 membrane was obtained in the presence of water but only at high activity (∼0.8). Besides, the dispersion of the water molecules in the membrane was found to be homogeneous. The infrared spectroscopy results revealed that the methanol molecules had weaker interactions with the sulfonic groups of IonClad R4010 in agreement with the sorption data. The permeation properties were investigated by means of the sweeping gas and gravimetric methods in order to evaluate the membrane performance for pervaporation. The permeation results are in accordance with those obtained by sorption, thus confirming the complementariness of the two approaches.