Maria Inês Rouxinol

Isolation and identification of phenolic compounds are crucial processes in the field of natural product chemistry and biochemistry. Phenolic compounds are secondary metabolites widely distributed in plants, exhibiting diverse biological activities with potential health benefits. The isolation involves extracting these compounds from plant sources using various techniques such as solvent extraction, steam distillation, or solid-phase extraction. Following isolation, identification is accomplished through sophisticated analytical methods like high-performance liquid chromatography, gas chromatography-mass spectrometry, and nuclear magnetic resonance spectroscopy. These methods allow researchers to characterize and quantify specific phenolic compounds, elucidating their structures and understanding their roles in plant physiology and human health. The isolation and identification of phenolic compounds contribute significantly to the exploration of natural resources for pharmaceutical, nutritional, and industrial applications.

Consumers are looking for safer and more natural food options that are produced through natural methods without using synthetic preservatives. They also desire extended shelf life for their food products. Several medicinal and aromatic plants species combine food, spice, aromatic, and medicinal recognized attributes. The essential oils from these plants contain a unique mixture of compounds specific to each plant, showing notable antioxidant and antimicrobial properties. Essential oils are used widely as they are environmentally friendly, non-toxic, and biodegradable substitutes for harsh chemical preservatives. Thyme and clove are aromatic plants commonly used in traditional gastronomy, particularly in meat-based recipes. The preservation effects of these essential oils on fresh meat have not been widely studied. Therefore, the aim of this study is to review the use of thyme and clove essential oils in meat preservation, with particular emphasis on their antioxidant properties to mitigate lipid and protein oxidation. Different strategies have been used to boost the effects of essential oils in foods, which include mixtures of essential oils, encapsulation and nanoemulsification techniques, with or without edible coatings. The final objective is to promote the wide use of essential oils for meat preservation, eventually in combination with other innovative approaches.

The prickly pear is a non-climacteric fruit and highly perishable. Therefore, it is crucial to find methods to extend its shelf life. The objective of this study was to evaluate the storage behavior of prickly pears under modified atmosphere conditions (2 °C, 90% RH) using different packaging materials (a cardboard box commercially used by the company, a rigid PET (polyethylene terephthalate) box, and a biodegradable plastic flexible bag). The fruits were produced in the Alentejo region and belong to a regional variety usually referred to as the “orange” variety. According to this study, the “orange” variety fruits could be stored at the specified temperature for 30 days. Among the storage methods tested, the biodegradable plastic bag was the most effective in maintaining the fruit’s quality throughout the entire period. The biodegradable package exhibited a weight loss lower than 5% for 30 days of storage, while the cardboard box showed great weight loss (>6%) and more fruit contamination by fungi. Fruit firmness also decreased during storage, going from 10.1 N to 4.35 N, with bigger losses happening in the PET box. Throughout the study, the fruit acidity remained stable with values of 0.03% and 0.02%.

Red wine grapes have an important impact on the economy of many regions, both for wine quality and for their richness in phenolic compounds, which have many health benefits. Climate has been changing substantially in the last years, which affects greatly grape polyphenolic composition and wine quality. In this review, we will unveil the importance of climate in grape development, both physically and chemically, the different methodologies used to evaluate grape quality, the interesting new approaches using NIR spectroscopy, and the functional properties of grapes and red wine, due to their high phenolic content. Climate has an impact in the development of phenolic compounds in grapes, namely in the anthocyanins biosynthesis. The phenolic chemical composition changes during maturation, therefore, it is essential to keep on track the accumulation of these key compounds. This information is crucial to help producers choose the best harvest date since specific compounds like polyphenols are responsible for the color, taste, and mouthfeel of wines, which directly affects wine quality. The usage of different methodologies to assess quality parameters in grapes and wine, can be used to provide essential information to create the chemical profile of each variety to develop calibration methods. NIR spectroscopy seems to be a reliable method to be used in vineyards during grape maturation to provide real time information on quality parameters to producers since many reliable calibration models have been developed over time.

Wine quality is determined by the development of grape maturation, which is highly dependent on climate variations. Extreme weather events are becoming more common, which will affect the productivity and quality of grapes and wine. Grape development depends on many factors, including weather, and extreme events will influence berry size, skin thickness and the development of some key compounds, such as phenolics. In this work, the ripening evolution and phenolic content of Vitis vinifera extracts from a vineyard in Alentejo (Portugal) were evaluated in two distinct climatic years. During this period, the influence of climatic conditions on grape ripening, and thereby on red wine quality, was assessed. The results demonstrate differences in polyphenol compounds between years and the importance of monitoring their content during maturation. The reduction of berry size, apparently due to lower pluviosity and higher temperatures, resulted in a higher content of polyphenolic compounds related to grape quality.

Red wine grapes require a constant follow-up through analytical chemistry to assure the greatest wine quality. Wet chemical procedures are time-consuming and produce residues that are hard to eliminate. NIR (near infrared radiation) spectroscopy has been referred as an accurate, rapid, and cost-efficient technique to evaluate quality in many fruit species, both in field and in industry. The main objective of this study was to develop predictive models using NIR spectroscopy to quantify important quality attributes in wine grapes. Soluble solids content (SSC), titratable acidity (TA), total phenolic content, total flavonoids, total anthocyanins, and total tannins were quantified in four red wine grape varieties, ‘Aragonês’, ‘Trincadeira’, ‘Touriga Nacional’, and ‘Syrah’. Samples were collected during 2017 and 2018 along véraison. Prediction models were developed using a near-infrared portable device (Brimrose, Luminar 5030), and spectra were collected from entire grapes under near field conditions. Models were built using a partial least square regression (PLSR) algorithm and SSC, TA, total anthocyanins, and total tannins exhibited a determination coefficient of 0.89, 0.90, 0.87, and 0.88, respectively. The Residual Prediction Deviation (RPD) values of these models were higher than 2.3. The prediction models for SSC, TA, total anthocyanins, and total tannins have considerable potential to quantify these attributes in wine grapes. Total flavonoids and total phenolic content were predicted with a slightly lower capacity, with R² = 0.72 and 0.71, respectively, and both with a RPD of 1.6, indicating a very low to borderline potential for quantitative predictions in flavonoids and phenols models.

Nowadays there is a search for new alternatives to replace harsh and expensive chemical methods to wastewater treatments. The common methods include the usage of chemicals that negatively affect the environment and the human health. The cladodes of Opuntia ficus-indica (L.) Mill have a great...