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In this work, a selection of food-grade ceramic materials (CM1, CM2) was evaluated in terms of capacity to adsorb pathogenesis-related proteins (PRPs), thus preventing protein haze in bottled white wines. The CM1 was found as the most effective sorbent material, when used in a nano-structured form (nanopowders and mesoporous films) which magnifies the specific surface available for adsorption. The material showed a high affinity and selectivity to low molecular weight proteins, thus allowing the stabilisation of white wines without altering key quality parameters. The most captivating aspect of using CM1 consisted in the possibility of producing thin and mesoporous films anchored to inert supports, to obtain composite materials that are easy to handle and safe from a food point of view. The composite material CM1 was tested in a wine flow treatment device, confirming excellent performance in terms of stabilisation. Based on the results obtained, the stabilising material and the stabilisation method proposed can be further implemented to be used in a pilot plant and exploited in the wine industry.

While red wine phenolics have been extensively studied, polysaccharides and proteins have not received the same level of attention, especially when considering Italian wines. In this study, for the first time, quantitative and qualitative data on the macromolecular (proteins and polysaccharides) and tannin composition of 110 monovarietal red wines from 11 of the most important Italian grape varieties are reported. The winemaking did not include any filtration, oak contact, fining treatments, or ageing on yeast lees. Results highlighted a great inter- and intra- varietal diversity. The protein content ranged between 0 and 159 mg/L, polysaccharides between 211 and 1081 mg/L and total tannins between 171 and 3746 mg/L, with averages of 41 mg/L, 497 mg/L and 1687 mg/L, respectively. Six varieties with protein content representative of the variability observed were selected and submitted to electrophoresis. Within each variety, the SDS-PAGE mobility of protein-tannin complexes was similar but showed two distinct patterns for wines of different varieties (higher mobility for Corvina, Teroldego and Raboso Piave, lower mobility for Nebbiolo, Aglianico, Cannonau), suggesting that the Italian monovarietal wines can be diverse also in their colloidal-forming structures. This can be explained by looking at the different percentages of protein-reactive tannins (TBSA) on the total tannin content (TMCP), which is a varietal characteristic.