Effect of Drying Methods on Bioactive Compounds and Antioxidant Capacity in Grape Skin Residues from the New Hybrid Variety "BRS Magna"

A-type proanthocyanidins: Sources, structure, bioactivity, processing, nutrition, and potential applications

A-type proanthocyanidins (PAs) are a subgroup of PAs that differ from B-type PAs by the presence of an ether bond between two consecutive constitutive units. This additional C-O-C bond gives them a more stable and hydrophobic character. They are of increasing interest due to their potential multiple nutritional effects with low toxicity in food processing and supplement development. They have been identified in several plants. However, the role of A-type PAs, especially their complex polymeric form (degree of polymerization and linkage), has not been specifically discussed and explored. Therefore, recent advances in the physicochemical and structural changes of A-type PAs and their functional properties during extraction, processing, and storing are evaluated. In addition, discussions on the sources, structures, bioactivities, potential applications in the food industry, and future research trends of their derivatives are highlighted. Litchis, cranberries, avocados, and persimmons are all favorable plant sources. Α-type PAs contribute directly or indirectly to human nutrition via the regulation of different degrees of polymerization and bonding types. Thermal processing could have a negative impact on the amount and structure of A-type PAs in the food matrix. More attention should be focused on nonthermal technologies that could better preserve their architecture and structure. The diversity and complexity of these compounds, as well as the difficulty in isolating and purifying natural A-type PAs, remain obstacles to their further applications. A-type PAs have received widespread acceptance and attention in the food industry but have not yet achieved their maximum potential for the future of food. Further research and development are therefore needed.

Grape skin flour obtained from wine processing as an antioxidant in beef burgers

The objective of this study was to determine the best level of wine making by-product meal (WBM) as a natural antioxidant to replace butylhydroxytoluene (BHT) in beef burger stored at -20 °C for up to 120 days. The treatments consisted of control (basic formulation - BF, without antioxidant); BF with BHT; and BF with WBM0.5, WBM1.0, WBM1.5, and WBM2.0, with 0.5, 1.0, 1.5 and 2.0 g WBM/100 g BF, respectively. Up to 60 days of storage, the lipid oxidation value between BHT and WBM0.5 treatments did not differ and were lower than the values presented by the other treatments. On day 90 and 120, the lipid oxidation values of treatments BHT, WBM0.5, and WBM1.0 did not differ and were lower than the values presented by WBM1.5 and WBM2.0 treatments. Burgers from all treatments with WBM inclusion had crude fiber values above 3 g/100 g. WBM1.5 and WBM2.0 treatments had the worst scores for appearance, aroma, juiciness and tenderness, in addition to the highest cooking losses. WBM can be used at up to 1 g/100 g to replace BHT in frozen beef burgers. Higher levels of WBM inclusion increased lipid oxidation and negatively affected the sensory quality of burgers.

Optimisation of Instant Controlled Pressure Drop (DIC)-assisted dehydrofreezing using Response Surface Methodology towards better bioactive compounds retention of quince fruit

Pre-drying prior to freezing may reduce several freezing drawbacks. Nevertheless, drying may cause nutritional quality losses. Instant Controlled Pressure Drop process has been proposed to intensify pre-drying process. This research is dedicated to study the evolution of the main bioactive compounds (total phenolics, flavonoid, and tannins contents) of quince dehydrofrozen fruits. Fresh samples were subjected to air drying at 40 °C and 3 m s−1 air velocity down to a final water content of 0.3 g g−1 db. Pre-dried samples were Instant Controlled Pressure Drop (DIC) treated under different conditions, i.e. saturated steam pressure (P) and treatment time (t), following a 2-factor/5-level Experimental Design. Treated fruits were frozen at –30 °C then were thawed at 20 °C in order to study the impacts of DIC on phenolic compounds. Response Surface Methodology (RSM) confirmed that pressure was the most influencing parameter in terms of polyphenol, flavonoid, and tannins contents. Finally, DIC pre-treatment allowed the improvement of phenolic content retention compared to untreated DIC samples.

Syrah Grape Skin Residues Has Potential as Source of Antioxidant and Anti-Microbial Bioactive Compounds

Simple Summary

The aim of this study was to verify the influence of different extraction parameters (temperature and ultrasound time) of bioactive compounds from the skin of the Syrah variety of grape. Among the extracts obtained, those exposed to 20 min of sonication had the best results in terms of flavonoid content, antioxidant potential and phenolic profile. The temperature of 60 °C provided the most relevant results for the content of total phenolics, stilbenes, flavonols and phenolic acids, however, the association of this temperature with the use of ultrasound showed lower results as a source of antioxidant and antimicrobial bioactive compounds.

Abstract

In this study, we evaluated the effects of ultrasound-assisted extraction (UAE) under different time-temperature conditions on the content of bioactive compounds, antioxidant and antimicrobial activities of Syrah grape skin residue. The application of UAE showed a positive effect on the extraction of total flavonoids, and a negative effect on total polyphenols. The temperature of 40 °C and 60 °C without the UAE caused an increase of 260% and 287% of the total polyphenols, respectively. Nineteen individually bioactive compounds were quantified. The anthocyanin concentration (malvidin-3,5-di-O-glucoside 118.8–324.5 mg/100 g) showed high variation, to a lesser extent for phenolic acids, flavonoids, flavonols, procyanidins and stilbenes due to the UAE process. The Syrah grape skin residue has a high concentration of total phenolic compounds of 196–733.7 mg·GAE/100 g and a total flavonoid content of 9.8–40.0 mg·QE/100 g. The results of free radical scavenging activity (16.0–48.7 mg/100 mL, as EC₅₀) and its inhibition of microbial growth (0.16 mg/mL, as EC₅₀ for S. aureus, and 0.04 mg/mL, as EC₅₀ for E. coli) by grape skin extract (UAE 40:20) indicate high antioxidant and antibacterial activity. It was concluded that the use of ultrasound needs further analysis for its application in this context, as it has shown deleterious effects on some compounds of interest. Syrah grape skin residue has potential as a source of bioactive antioxidants, antimicrobial activity and for use as a functional food ingredient.

Development of a Simple High-Performance Liquid Chromatography-Based Method to Quantify Synergistic Compounds and Their Composition in Dried Leaf Extracts of Piper Sarmentosum Roxb

There is a growing demand to enhance pharmaceutical and food safety using synergistic compounds from Piper sarmentosum Roxb., such as polyphenols and water-soluble vitamins. However, information on standardized analytical methods to identify and quantify these compounds of interest is limited. A reversed-phase high-performance liquid chromatography with diode-array detection (HPLC-DAD)-based method was developed to simultaneously detect and quantify the amounts of tannin, flavonoid, cinnamic acid, essential oil, and vitamins extracted from P. sarmentosum leaves using methanol, chloroform, and hexane. Commercially and non-commercially-cultivated P. sarmentosum leaves were subjected to seven different drying treatments (shade; sun; air oven at 40 °C, 60 °C, 80 °C, and 100 °C; and freeze-drying) for three consecutive months. Most compounds were detected most efficiently at a detection wavelength of 272 nm. The developed method displayed good detection limits (LOD, 0.026–0.789 µg/mL; LOQ, 0.078–2.392 µg/mL), linearity (R2 > 0.999), precision (%RSD, <1.00), and excellent accuracy (96–102%). All P. sarmentosum leaf extracts were simultaneously tested and analytically compared without time-consuming fractionation. Methanolic plant extracts showed better peak area and retention time splits compared to chloroformic and hexanoic extracts. Differences in synergistic compound composition were dependent on the type of drying treatment but not on cultivation site and time of sampling. Flavonoid was identified as the dominant phytochemical component in P. sarmentosum leaves, followed by the essential oil, cinnamic acid, ascorbic acid, and tannin. Overall, we present a simple and reproducible chromatographic method that can be applied to identify different plant compounds.