The objective of this PhD research project has been to evaluate some characteristics (e.g., allergens content, polyphenols profile and antioxidant potential) of the Italian ciders that could affect the human health.
In this way we tried to promote the product contributing to improve the knowledge needed to better the production techniques.
The first aspect described in this PhD study was the recovery of cider proteins (Chapter 2). The rationale was the knowledge that, in other fermented beverages, these molecules are described to be involved in specific organoleptic characteristics such as foam stability, in the interaction with the aroma compounds in the formation of hazes and sediments. In addition, proteins could elicit allergenic reactions in sensitive individuals.
After the setup of the recovery methods, proteins purified from 18 commercial ciders were identified by LC-MS/MS technique. This high sensitive method revealed the presence of Mal d 2 and Mal d 3 proteins in all the cider samples analyzed. In addition, this technique showed that 12 out of 18 ciders are contaminated by hen egg lysozyme that is a well-known allergen, even if its use and presence was not declared on the label as stated by the EU Directive. Since the LC-MS/MS analysis detects only fragments of protein that could not be immunologically active, ELISA and western blot analyses were achieved for the detection of lysozyme. Two samples out of 18 were both positive to the assays applied and this confirm the immunological activity of the protein and the existence of a serious health concern to drink cider for people sensitized to egg (Chapter 3).
The following step was to study the effect of cidermaking procedure on apple allergen. For this reason, the immunological activity of Mal d 2 and Mal d 3 proteins was tested with specific antibodies developed in rabbit. Six and four samples out of the 13 ciders considered were positive to Mal d 2 and Mal d 3, respectively. It is important to highlight that not all the samples showed a positive match to both the apple allergens. This could indicate that the technological process in cidermaking could achieve a selective removal of specific allergens. Moreover, as regarding Mal d 3 the antibody detected an ambiguous signal at the level of the stacking gel of almost all samples (Chapter 4).
Finally, an aspect related to the wholesomeness of cider was investigated. The polyphenols profiles of 18 Italian ciders were correlated with their antioxidant activity, and a multiple linear regression model was drawn to predict the antioxidant potential of the beverage, knowing the concentration of specific phenols (namely: chlorogenic acid, catechin, procyanidins B1 and B2, quercetins 3-glucoside, 3-xyloside and 3-arabinopyranoside). This suggests that these phenols could be the mainly contributors of the antioxidant activity, but further studies should be performed to exclude that this correlation could be only an epiphenomenon consequence of particular interactions among different molecules. Anyway the total antioxidant activities of Italian ciders results on average lower than those reported in literature for Asturian ones and this could be probably related to the total polyphenols content and their profiles (Chapter 5).
This observation suggests that the Italian cidermaking process could be ameliorated taking in consideration both the allergenic profile of the beverage and the preferences of the Italian consumers
