Ultrasound and microwave techniques for assisting ageing on lees of red wines.

Ageing on lees is a slow process that carries microbiological and economic risks in the wineries. This study evaluates the possibility of enhancing the extraction of different compounds from the lees, using combined strategies, such as ultrasound (US) or microwaves (MW) and the addition of inactive dry yeasts (IDY), to reduce the lees ageing time. The complete chemical analysis of the wine was done, amino acids, polysaccharides, colour and volatile compounds, together with the sensory analysis. The combined treatments increased the release of total polysaccharides, mannoproteins and total monosaccharides in the wines, and some amino acids like proline. However, wines treated with US and MW, with and without lees, showed a decrease in tannins and colour intensity, and in some volatile compounds like fatty acid esters, acetates and terpenes. The wines treated with IDY and MW were the best valued for their floral and red berry flavours and less astringency.

Implementation of subcritical water extraction with natural deep eutectic solvents for sustainable extraction of phenolic compounds from winemaking by-products.

In attempt to recover valuable phenolic compounds from grape pomace by-products, a new implemented methodology has been proposed. The subcritical water extraction technique has been implemented with the use of emerging eco-solvents such as natural deep eutectic solvents (NADESs). The extraction efficiency of different NADESs were screened. Among them, choline chloride containing urea as hydrogen bond donor was selected (ChClU). However, due to pressurised system and the viscosity of NADESs, ChClU could not be used as truly solvent but as a solvent modifier in an promising percentage of 30%. The optimum extraction temperature for the isolation of phenolic compounds was 100 °C since extractions above this temperature implied the loss of the original composition of grape pomace due to thermaldegradation reactions and neoformation of Maillard compounds. The employ of subcritical water combined with 30% of ChClU led to a significant rise of extracted phenolic compounds quantities in comparison with the solely use of subcritical water. Among them, the extraction of catechin and epicatechin suffered an increase of 45.05 and 47.98% respectively, so this implementation led to highly efficient and truly eco-friendly extraction method. The implementation of subcritical water with NADESs to extract valuable compounds from winery by-products has not been applied until now.

Oak wood extracts as natural antioxidants to increase shelf life of raw pork patties in modified atmosphere packaging.

The use of antioxidants and refrigeration storage in modified atmosphere packaging, MAP, are the main strategies to slow down the oxidative and microbial deterioration of fresh meat. Synthetic antioxidants are commonly used for this purpose, however due to their controversial health effects, natural alternatives for their replacement are being looked for. The main aim of this work is the evaluation of pressurised aqueous extracts from oak wood as natural preservative of pork patties. The effect of different amounts of oak wood extracts (0.05, 0.5 and 1.0%) on the self-life of pork patties packed in MAP in refrigeration during 12 days were studied in comparison with the use of sodium ascorbate as synthetic preservative. Samples treated with oak wood extracts showed lower lipid oxidation, higher antioxidant capacity and an inhibitory effect on the enterobacteria growth. Furthermore, the addition of oak wood extracts resulted in a dramatically decrease of the volatile compounds coming from the lipid oxidation reactions. On the other hand, it is noteworthy that the use of oak wood extracts modified sensorial characteristics. Intensity colour was higher and new sensorial features such as oak wood and sweet spices appeared which were well appreciated.

Alternative amendment for vineyards from by-products of pyro-bituminous shale: Effect on wine amino acids and biogenic amines.

With the aim of looking for a model of agroecological production, the use of by-products from pyro-bituminous shale as amendment, and its effect on wine amino acids and biogenic amines has been evaluated. Field trials aimed to compare the effect of different doses of conventional and limestone shale from by-products of pyro-bituminous. Four replicates for six different fertilization treatments were arranged in a split plot design during 2009/2010 and 2010/2011 vintage. A chromatographic analysis was carried out to evaluate the impact of fertilization treatments on the amino acid and biogenic amine content of wines produced. Results showed few significant differences among fertilization treatments tested according to the amino acids composition of wines, although it seemed that a combination of conventional and pyro-bituminous shale could be the best option. By-products of pyro-bituminous shale seem to be a good partial substitutive amendment for Brazilian vineyards. This research seems to be a new approach for sustainable revalorization of domestic fertilizers to enable minor environmental impacts and lower production costs without detriment to quality.

Effect of freeze-drying and oven-drying on volatiles and phenolics composition of grape skin.

Grape skins are the part of the fruit with the highest amount of volatile and polyphenolic compounds. Volatile compounds give the fruit and other grape derivatives their flavour. Polyphenolic compounds are responsible for the colour of the fruit, juice and wine, and also act as very important natural antioxidant compounds. Dehydration is a method used to prevent the damage of these compounds over time. Nevertheless, in the case of volatile compounds, removing water can cause compound degradation or the evaporation of such compounds. This work studied two drying methods, freeze-drying and oven-drying, at 60 degrees C, as skin preservation methods. The skins from two grape varieties, Carménère and Cabernet Sauvignon, were dried. Many volatile compounds, which are of interest in the aroma profile, were identified in both varieties as terpenes (linalool, etc.), sesquiterpenes (farnesol), norisoprenoids (vitispirane, etc.), C(6) alcohols (1-hexanol, etc.), etc., and their amount decreased significantly with the oven-drying method, in contrast to the freeze-drying method. Both phenolic compounds, anthocyanins and flavonols, were identified in fresh and dehydrated samples, thus resulting in the freeze-drying method being less aggressive than oven-drying methods.

Comparison of extraction methods for volatile compounds of Muscat grape juice.

Typical flavour of Muscat d'Alexandrie wines is mainly due to volatile compounds coming from grapes of this variety. Therefore, the choice of grapes is crucial to obtain musts with a great aromatic potential, which will contribute to the final aroma of wines derived from those musts. In this study, three sampling techniques, liquid-liquid extraction (LLE), solid phase extraction (SPE) and simultaneous distillation-extraction (SDE), were compared for the analysis of volatile compounds in Muscat grape juice. Results showed that although the three techniques can be recommended for the quantitative analysis of volatile compounds from musts, LLE and SPE are better sample preparation techniques than SDE, mainly for determination of polar compounds such as acids or alcohols.

Influence of storage conditions on chemical composition and sensory properties of citrus honey.

Fresh citrus honey was stored at 10, 20, and 40 degrees C for 12 months. The effect of storage on the quality of honey was evaluated using physicochemical parameters, volatile compounds, mono-, di-, and trisaccharides, and sensory analysis. Diastase activity and HMF were out of the legal limit in honey stored 12 months at 40 degrees C. Volatile compounds (especially terpenes and terpene derivatives), monosaccharides, and disaccharides presented important losses during honey storage at any temperature. Honey storage at 10 or 20 degrees C maintained their floral, fresh, citric, and fresh fruit aroma, while the intensities of these attributes were diminished. Storage at 40 degrees C during 12 months resulted in the appearance of attributes such as "medicinal, smoked, toasted, cooked vegetable, and ripened fruit", associated with compounds formed during the Maillard reaction or through degradation of sugars such as volatile pyrroles, furanones, pyranones, and pyrazines, which appeared or increased in concentration during honey storage mainly at high temperature.