Giorgia Spigno

Characterization of phenolics, in vitro reducing capacity and anti-glycation activity of red grape skins recovered from winemaking by-products

Red grape skins recovered from ten winemaking processes were analyzed for total phenolic content (Folin Ciocalteu assay), proanthocyanidins (n-butanol/HCl assay), individual phenolics (UPLC-DAD-MS), in vitro ferric ion reducing capacity and anti-glycation activity by bovine serum albumin/fructose and bovine serum albumin/methylglyoxal model systems. The aim was to assess if these by-products have potential as dietary anti-glycation agents, to prevent the glyco-oxidative stress associated with type-2 diabetes. Variability was observed in total phenolics (12.1-53.6g gallic acid Eq/kg), proanthocyanidins (7.2-51.1g/kg), anthocyanins (2.5-13.8 g malvidin 3-O glucoside Eq/kg), flavonols (0.3-2.6g quercetin 3-O glucoside Eq/kg) and reducing capacity (103-511 mmol Fe(II) Eq/kg). For all samples, the anti-glycation effectiveness was higher than that of commercial nutraceutical preparations. Hence, in spite of differences in cultivar, location of the vineyard and winemaking procedures, these by-products could be used as a source of cost-effective anti-glycation agent either as a food ingredient or as a nutraceutical preparation.

Autohydrolysis and organosolv process for recovery of hemicelluloses, phenolic compounds and lignin from grape stalks.

A combination of two environment-friend processes for hemicelluloses and lignin recovery from red grape stalks were investigated: an autohydrolysis pretreatment at 180°C for 30 min followed by a non-catalysed ethanol organosolv step at 180°C for 90 min. Hemicelluloses were precipitated by ethanol addition to autohydrolysis liquor, while lignin was tentatively precipitated by acidification of liquors from both the processes. Results suggest that stalks hemicelluloses can be easily hydrolysed requiring a milder treatment to reduce sugar degradation, while the organosolv process did not give a consistent delignification. Autohydrolysis allowed a recovery of 2% (on stalks d.m.) of total phenols in the liquor. Organosolv liquor had a higher concentration of phenols (corresponding to 0.72% of stalks d.m.) which almost completely precipitated with lignin.

Nutrition and Ageing

The world elderly population is rapidly increasing. This demographic change represents a new challenge for the society and demands for a multisectorial intervention to promote a long, healthy, and active life span. Between the factors that contribute in fostering a long healthy life, the nutritional regime plays a central role and is recognized as a major factor in the onset of chronic diseases. A better understanding of the interaction between nutrition and ageing is essential to unravel the mechanisms responsible for these positive/negative effects and to identify diet components promoting the quality of life in the old age and to contribute to the prevention of late-life disabilities. At Università Cattolica del Sacro Cuore, the research activity in food science is focusing on four main objectives: food quality, food safety, functional foods and diet balancing. These objectives are the target of multidisciplinary ongoing and future research activities for a better understanding of the link between diet and ageing. Briefly, the different activities are addressed to the study of the following subjects: the most relevant factors affecting food choices and habits of old aged persons; the effects of long term low dose supplementation of conjugated linoleic acid in mouse; the use of low glycemic index and high resistant starch foods to prevent diabetes and obesity; the adjuvant effect of food bacteria for vaccination; the role of food ingredients in disease; the immunosuppression effect of mycotoxins, and its relevance in ageing people; the production of sustainable and natural antioxidant ingredients to encourage a healthy diet. Our research projects emphasize an holistic and integrated approach that, by bringing together complementary research groups, can combine the collective expertise and thus provide a comprehensive assessment of the role of nutrition in healthy ageing people.

Recovery of gallic acid with colloidal gas aphrons (CGA)

In the present paper the potential application of colloidal gas aphrons (CGA) to the recovery of antioxidants from wine-making waste extracts is investigated. CGA were generated by stirring a buffered solution (400 ml) of a cationic surfactant(cetyltrimethylammonium bromide, CTAB) at 8000 rpm for 10 minutes. Trials were carried out on standard solutions (2 ml) of gallic acid (GA) 200 mg/l with varying volumes of colloidal gas aphrons (20-60 ml) generated with varying concentrations of CTAB (2 and 4 mM). Influence of pH, solvent (buffered aqueous solution and ethanol), CTAB to GA molar ratio on recovery were studied. Best recovery (63%) was achieved from an aqueous solution of GA and at a CTAB to GA molar ratio of 16. Separation is mainly driven by electrostatic interactions but pH conditions are to be optimised to preserve the GA antioxidant power.

Microwave-Assisted Extraction of Phenolic Compounds from Dried Waste Grape Skins

Abstract Microwave-assisted extraction (MAE) was investigated for recovering of total phenolic compounds from dried waste grape skins using a domestic microwave oven. Influence of vessel geometry, irradiation cycles, irradiation power and time was investigated. The results in terms of phenolics yield, antioxidant capacity and energy consumption were compared with a reference solid–liquid extraction (SLE) carried out for 2 h at 60°C. Equivalent yield of total phenolics as in SLE was achieved with a MAE extraction time of 1,033 sec (corresponding to 83 sec of irradiation at 900 W, 83% saving in extraction time compared to SLE and with a 70% energetic efficiency). Pre-maceration of samples and solvent pre-heating are proposed for large-scale industrial processes to enhance phenolics extraction and process efficiency.

Modelling the stability of maltodextrin-encapsulated grape skin phenolics used as a new ingredient in apple puree.

Highly soluble maltodextrin-encapsulated grape skin phenolics comprising anthocyanins and less hydrophilic flavonoids were added as an ingredient to apple puree. Upon formulation, heat treatments were applied to achieve 3-14 decimal reductions (D) of the target microorganism (Alicyclobacillus acidoterrestris). A storage study was performed at 15-35°C for 1month. Monomeric anthocyanins were retained at 100% after the 3 D treatment, while anthocyanin retention decreased to 72% with increasing heating intensity until 14 D. During storage, the concentration of monomeric anthocyanins decreased following first-order kinetics (k25°C=34.4d(-1), activation energy=51.0kJ/mol). The flavanols were more stable than the monomeric anthocyanins. The hydroxycinnamic acid, dihydrochalcone and flavonol contents did not change. The fortified puree had a two-fold higher reducing capacity with respect to apple puree. Overall, this ingredient could meet the industrial demand for sustainable colouring agents and health promoting compounds.

Waste grape skins : evaluation of safety aspects for the production of functional powders and extracts for the food sector

ABSTRACT Skin powders and aqueous alcohol extracts were obtained from waste marcs from different grape varieties (Barbera, Nebbiolo, Pinot Noir, Chardonnay, Moscato and Müller-Thurgau). Both skins and extracts were analysed for the content of chemical contaminants: ochratoxin A (OTA), biogenic amines (BIAs), pesticides and metals. OTA was detected in low concentrations in Barbera, Moscato and Nebbiolo skins, but only in Barbera and Moscato extracts. Cadaverine, putrescine, ethanolamine and ethylamine were found in extracts at very low levels, while potential allergenic amines, tyramine and histamine, were never detected. Different pesticides were present in both skins and extracts. Pb and Cd were found in trace only in the powders, and K, Ca and Mg were the most abundant elements in both skin powders and extracts. Concentrations of the different contaminants were related to fibre content or total phenolics content of powders and extracts, respectively, in order to evaluate their use in the food sector. Graphical Abstract

Optimization of Ultrasound-Assisted Extraction of Phenolic Compounds from Citrus sinensis L. Peels using Response Surface Methodology

The aim of this study was the optimization, by Response Surface Methodology (RSM), of Ultrasound Assisted Extraction (UAE) conditions for the recovery of phenolic compounds from C. sinensis peels with aqueous acetone at room temperature. A Central Composite Rotatable Design (CCD) was applied to determine the effects of extraction time (X1, 5-15 min), extraction amplitude (X2, 30-70%), and acetone concentration (X3, 30-70 %) on Total Phenolic Content (TPC expressed as Gallic Acid Equivalents GAE, according to the Folin’s assay) of the extract. The independent variables were coded at five levels and their actual values were selected based on the results of single factor experiments. Results showed that acetone concentration and extraction amplitude were the most significant (p<0.05) factors affecting the TPC yield. The optimum extraction conditions were found to be 8.33 min extraction time, 65.94 % extraction amplitude and 75.79 % acetone concentration. Under the optimized conditions, a TPC yield of 13.57±0.71 mgGAE/gdw was obtained which resulted very close to the predicted value of 14.16 mgGAE/gdw.

Fractionation of a Red Grape Marc Extract by Colloidal Gas Aphrons

The objective of the current study was to investigate the application of colloidal gas aphrons (CGA) as a potential low-cost technology for the fractionation of phenolic extracts obtained from off-skins fermented red grape skins with high sugar content. The trials were aimed to investigate the possibility of using CGA generated from the non-ionic surfactant Tween20 to separate phenolic compounds from non-phenolic compounds (minerals and sugars) and to fractionate different fractions of phenolic compounds (total phenols, cinnamic acids and anthocyanins). Separation tests were carried out in a 0.7 L flotation column investigating the effect of both the volumetric ratio CGA/extract sample and the molar ratio CGA/extract sample on both the recovery yields and the separation factor (the ratio between the concentration of a compound in the recovered aphron phase and in the discharged liquid phase). Results revealed the possibility of reaching high recovery yield even though with a poor selective fractionation of the different compounds present in the extract, with glucose and cinnamic acids showing the highest affinity for the aphron phase.

Screening of four different agro-food by-products for the recovery of antioxidants and cellulose

Carried out under the European Project SusFoFlex, this study aimed the investigation and selection of different agro-food by-products for the recovery of antioxidants and cellulose to be further exploited for application in the development of innovative and sustainable food packaging materials. Based on literature data and partners’ countries availability, four by-products were considered: brewers’ spent grains, wheat straw, hazelnut shells and orange peels. A common process for the production of antioxidant extracts (a two-step hydro alcoholic solvent extraction) and another for the fractionation of cellulose (an acid hydrolysis step followed by an alkali hydrolysis and, then, an oxidative bleaching step) was applied to all the materials with the objective of selecting ideally a unique by-product for the production of both antioxidants and cellulose. The extracts were characterised in terms of total phenols content (based on Folin assay and expressed as gallic acid equivalents) and antioxidant activity (evaluated with both the radical ABTS test and the Ferric Reducing/Antioxidant Power assay).The highest total phenols recovery was obtained for orange peels (9.50±0.66 mg per g of dried by-product), while the yields for the other byproducts were not statistically different and < 2 mg/g. Regarding the antioxidant activity, all the extracts showed very similar results with the ABTS assay, whereas orange peels extract exhibited the highest level of FRAP activity. The obtained cellulose residues were analysed for the total cellulose content and the level of lignin and hemicellulose impurities. In this case, the best by-product resulted wheat straw, with the recovery of 45 % of the original cellulose, a cellulose content (purity) of 84 % and residual impurities of hemicelluloses and lignin of 2 % and 12 %, respectively.