Influence of polysaccharides and glycerol on proanthocyanidin precipitation by protein fining agents

Enhancement of chitosan-based film physicochemical and storage properties by interaction with proanthocyanidin and natural deep eutectic solvent

Deep eutectic solvent (DES) has been recognized as a promising plasticizer for the preparation of biodegradable food packaging films. In addition, DES-plasticized chitosan (CS) films could also serve as a favorable carrier for loading active components. In this work, a ternary composite film was fabricated by plasticizing chitosan with DES and the active ingredient proanthocyanidin (PA) was used as a cross-linking agent. The incorporation of PAs significantly enhanced the toughness, elasticity, and hydrophobicity of the ternary CS-DES-PA composite films. It achieved antioxidant and bacteriostatic functions. In particular, the ternary CS-DES-PA composite films had a thickness of 0.16 ± 0.01 μm, a tensile strength of 2.63 ± 0.48 MPa, and an elongation about 73.22 %. They also have improved water resistance, UV blocking, with a high-water contact angle of 88.4° and a low water swelling of 5 % on the surface of the film. Meanwhile, the PAs in the film could slow down the browning of litchi fruits. This ternary blended film (CS-DES-PA) achieves better compatibility of the active ingredient in the film-forming substrate. It also provides a green and biodegradable packaging material for food packaging.

Effect of flotation and vegetal fining agents on the aromatic characteristics of Malvasia del Lazio (Vitis vinifera L.) wine

BACKGROUND

Flotation is a process to reduce the must turbidity after grape pressing. The use of fining agents to reduce the polyphenol content is essential for white wine, but their impact on volatile compounds must be considered. Malvasia del Lazio juice (Vitis vinifera L.) was treated before flotation with animal gelatin (GEL), legume protein plus chitin (LEGCHIT), and legume protein plus yeast extract (LEGYEAST). The clarification efficiency, total polyphenols, and total proteins were determined in the grape must before and after flotation, as well as the volatile composition and sensory characteristics of the resulting wines.

RESULTS

The LEGCHIT trial was the most efficient, it being the fastest and achieving the lowest turbidity values. The GEL trial was the slowest, showing grape must turbidity values similar to LEGYEAST but also the highest total protein content. The vegetal protein treatments caused a decrease in the concentration of volatile organic compounds (VOCs) with respect to gelatin, which resulted in a reduction of aroma intensity, particularly for fruity and floral notes, but also for green notes. Furthermore, LEGCHIT wines were appreciated by panelists for their greater body and reduced astringency perception.

CONCLUSION

The use of legume protein combined with chitin as a fining agent for flotation is advantageous in terms of clarification efficiency for grape must. Furthermore, the wines obtained showed high perceived global quality, even though a higher loss (38% and 27% respectively for LEGYEAST and LEGCHIT) of VOCs occurred when compared with gelatin. © 2020 Society of Chemical Industry.

Impact of alternative protein fining agents on the phenolic composition and color of Syrah red wines from warm climate

Currently, the wine industry has an increasing interest in developing alternative solutions to traditional animal proteins fining agents. In this study, the impact of different protein fining agents on the turbidity, phenolic composition and color of 2-month and 12-month Syrah red wines was assessed. Wines fined with egg albumin and plant-based proteins from potato, pea, and grape seed as recent alternative, were compared to unfined control wines. Changes on turbidity, phenolic composition and color (by Differential Colorimetry) showed that animal and plant proteins differed in their clarifying efficiency and ability to interact with colorless phenolics and anthocyanins, depending on the age of wine, with important consequences on color quality and stability. Plant proteins showed lower effectiveness to reduce wine turbidity than egg albumin but modified in different way the phenolic composition, inducing lower color differences with respect to control wine and similar stability, especially potato and grape seed proteins.

Oligosaccharides and Complex Carbohydrates: A New Paradigm for Cranberry Bioactivity

Cranberry is a well-known functional food, but the compounds directly responsible for many of its reported health benefits remain unidentified. Complex carbohydrates, specifically xyloglucan and pectic oligosaccharides, are the newest recognized class of biologically active compounds identified in cranberry materials. Cranberry oligosaccharides have shown similar biological properties as other dietary oligosaccharides, including effects on bacterial adhesion, biofilm formation, and microbial growth. Immunomodulatory and anti-inflammatory activity has also been observed. Oligosaccharides may therefore be significant contributors to many of the health benefits associated with cranberry products. Soluble oligosaccharides are present at relatively high concentrations (~20% w/w or greater) in many cranberry materials, and yet their possible contributions to biological activity have remained unrecognized. This is partly due to the inherent difficulty of detecting these compounds without intentionally seeking them. Inconsistencies in product descriptions and terminology have led to additional confusion regarding cranberry product composition and the possible presence of oligosaccharides. This review will present our current understanding of cranberry oligosaccharides and will discuss their occurrence, structures, ADME, biological properties, and possible prebiotic effects for both gut and urinary tract microbiota. Our hope is that future investigators will consider these compounds as possible significant contributors to the observed biological effects of cranberry.

Potato Protein Fining of Phenolic Compounds in Red Wine: A Study of the Kinetics and the Impact of Wine Matrix Components and Physical Factors

Producing wines within an acceptable range of astringency is important for quality and consumer acceptance. Astringency can be modified by fining during the winemaking process and the use of vegetable proteins (especially potato proteins) as fining agents has gained increasing interest due to consumers’ requirements. The research presented was the first to investigate the effect of a potato protein dose on the kinetics of tannin and phenolic removal compared to gelatin for two unfined Cabernet Sauvignon wines. To further understand the results, the influence of the wine matrix and fining parameters (including pH, ethanol concentration, sugar concentration, temperature, and agitation) were tested according to a fractional 2^5-1 factorial design on one of the Cabernet Sauvignon wines using potato proteins. The results from the factorial design indicate that potato protein fining was significantly influenced by wine pH, ethanol concentration, fining temperature as well as an interaction (pH × ethanol) but not by sugar content or agitation. Insights into the steps required for the optimisation of fining were gained from the study, revealing that potato protein fining efficiency could be increased by treating wines at higher temperatures (20 °C, rather than the conventional 10–15 °C), and at both a lower pH and/or alcohol concentration.

Applying Nanoparticle Tracking Analysis to Characterize the Polydispersity of Aggregates Resulting from Tannin-Polysaccharide Interactions in Wine-Like Media

Interactions between grape seed tannin and either a mannoprotein or an arabinogalactan in model wine solutions of different ethanol concentrations were characterized with nanoparticle tracking analysis (NTA), UV-visible spectroscopy and dynamic light scattering (DLS). NTA results reflected a shift in particle size distribution due to aggregation. Furthermore, the light scattering intensity of each tracked particle measured by NTA demonstrated the presence of aggregates, even when a shift in particle size was not apparent. Mannoprotein and arabinogalactan behaved differently when combined with seed tannin. Mannoprotein formed large, highly light-scattering aggregates, while arabinogalactan exhibited only weak interactions with seed tannin. A 3% difference in alcohol concentration of the model solution (12 vs. 15% v/v) was sufficient to affect the interactions between mannoprotein and tannin when the tannin concentration was high. In summary, this study showed that NTA is a promising tool for measuring polydisperse samples of grape and wine macromolecules, and their aggregates under wine-like conditions. The implications for wine colloidal properties are discussed based on these results.

Effect of physical interactions on structure of lysozyme in presence of three kinds of polysaccharides

In this work the influences of κ-carrageenan (CRG), konjac glucomannan (KGM) and inulin on lysozyme (Ly)'s structure, activity, and their complex phase behavior were investigated through spectroscopy and activity measurement in heated and unheated conditions. It was found that the impact on the structure and activity of Ly was determined by the interactions with polysaccharides. After heat treatment, KGM and CRG improved the stability of complex systems. However, inulin did not have significant impact. Heating process promoted to change the structure of Ly, and the intervention retard following the sequence of CRG > KGM > inulin. The worthwhile work indicated protein's structure and activity could be regulated by the interaction with polysaccharide, which might provide theoretical basis for food preservation and processing in different temperature treatments. Besides, the bidirectional effects of polysaccharide on protein would be beneficial to rational selection of functional properties of polysaccharide/protein systems.