Publications

Tea flavonoids are widely recognized as critical flavor contributors and crucial health-promoting bioactive compounds, and have long been the focus of research worldwide in food science. The aim of this review paper is to summarize the major progress in tea flavonoid chemistry, their dynamics of constituents and concentrations during tea processing as well as storage, and their health functions studied between 2001 and 2021. Moreover, the utilization of tea flavonoids in the human body has also been discussed for a detailed understanding of their uptake, metabolism, and interaction with the gut microbiota. Many novel tea flavonoids have been identified, including novel A- and B-ring substituted flavan-3-ol derivatives, condensed and oxidized flavan-3-ol derivatives, and glycosylated and methylated flavonoids, and are found to be closely associated with the characteristic color, flavor, and health benefits of tea. Flavoalkaloids exist widely in various teas, particularly 8-<i>C N</i>-ethyl-2-pyrrolidinone-substituted flavan-3-ols. Tea flavonoids behave significantly difference in constituents and concentrations depending on tea cultivars, plantation conditions, multiple stresses, the tea-specified manufacturing steps, and even the long-term storage period. Tea flavonoids exhibit multiple health-promoting effects, particularly their anti-inflammatory in alleviating metabolic syndromes. Interaction of tea flavonoids with the gut microbiota plays vital roles in their health function.

Hermida, R. C.; Ayala, D. E.; Calvo, C.; Dominguez, M. J.; Covelo, M.; Mojon, A.; Fernandez, J. R.; Fontao, M. J.; Soler, R.; Lopez, J. E. Author Information

Myricetin, a bioactive flavonoid, degrades rapidly in boiling water, limiting its use in functional foods and pharmaceuticals. This study explores the protective effect of vitamin C on the thermal degradation of myricetin and its mechanism of action. O-phenylenediamine derivatization identified reactive ortho-quinone intermediates, while density functional theory (DFT) calculations (ΔG = -47.74 kcal/mol) confirmed the redox mechanism. Vitamin C significantly improved myricetin retention from 32.8 % to 91.4 % in 0.8 mM after 100 min of heating, outperforming nitrogen treatment. Myricetin degradation begins with oxidation to ortho-quinones, which further degrades into phenolic acids and aldehydes. Vitamin C not only inhibited this process but also reversed oxidation by reducing ortho-quinones back to myricetin. These findings highlight vitamin C's potential to enhance flavonoid stability and bioavailability in functional heat-processed foods.

Active packaging has gained interest in recent years. As well as protecting food from the environment, it can incorporate agents with specific properties to extend the shelf life of the food. As a requirement, it is essential that the active agent has a greater affinity for the food than for the packaging material and, in this sense, essential oils (EOs) are potential candidates to be included in this new packaging system. The use of EOs can add to food matrix antimicrobial and antioxidant properties, reduce the permeability of the packaging to water vapor and extend the shelf life of food products. However, their use has been limited because they can produce a strong flavor by interacting with other compounds present in the food matrix and modify the organoleptic characteristics. Although the nanoencapsulation of EOs can provide chemical stability and minimize the impact of the Eos on the organoleptic properties by decreasing their volatilization, some physical modifications have still been observed, such as plasticizing effects and color variations. In this sense, the quality of the food products and consumer safety can be increased by using sensors. This technology indicates when food products are degrading and informs us if specific packaging conditions have changed. This work focuses on highlighting the use of biosensors as a new methodology to detect undesirable changes in the food matrix in a short period of time and the use of nanotechnology to include EOs in active films of natural origin.

Residues of pesticides in food are influenced by processing such as fermentation. Reviewing the extensive literature showed that in most cases, this step leads to large reductions in original residue levels in the fermented food, with the formation of new pesticide by-products. The behavior of residues in fermentation can be rationalized in terms of the physical-chemical properties of the pesticide and the nature of the process. In addition, the presence of pesticides decrease the growth rate of fermentative microbiota (yeasts and bacterias), which provokes stuck and sluggish fermentations. These changes have in consequence repercussions on several aspects of food sensory quality (physical-chemical properties, polyphenolic content, and aromatic profile) of fermented food. The main aim of this review is to deal with all these topics to propose challenging needs in science-based quality management of pesticides residues in food.