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Brewers’ spent grain (BSG) is the main solid by-product from the brewery industry, rich in valuable nutrients and bioactive compounds. The aim of this study was to valorize this by-product, recovering phenolic compounds from BSG using ultrasound-assisted extraction (UAE) and chemometric techniques, such as the response surface methodology (RSM). Therefore, UAE process parameters (temperature and time) and solvent composition (ethanol aqueous mixtures) were optimized using a three-level Box–Behnken design, in order to carry out the maximum yield in phenols. Then, the extract obtained under optimal conditions was characterized for the total phenolic content and antioxidant capacity (2,20-azino-bis(3-ethylbenothiazoline-6-sulphonic acid, ABTS, and 2,2-diphenyl-1-picrylhydrazyl, DPPH), and individual phenolic compounds were identified using HPLC-DAD. The results show the highest level of total soluble phenolic content (4.1 ± 0.1 mg GAE/g d.w.) at 80 °C, 50 min and 65:35% ethanol:water, with a high goodness of fit between experimental and predicted values (R2 = 0.987), and a high antioxidant potential (DPPH: 0.42 ± 0.01 mg TE eq/g d.w.; ABTS: 5.82 ± 0.04 mg TE eq/g d.w.). A comparison between the classic extraction techniques and the UAE with the same solvent showed an increase of 156% in the phenol yield. The characterization of phenolic profile revealed that ferulic acid (1.5 ± 0.2 mg/L), vanillic acid (0.78 ± 0.18 mg/L) and p-coumaric acid (0.12 ± 0.03 mg/L) were the prevalent ones. UAE coupled with RSM was a useful tool to inexpensively and quickly recover bioactive phenolic compounds from BSG, which can be used in the food, pharmaceutical or cosmetic industries.

High adherence to a Mediterranean diet (MD) is favourable for its sustainability and beneficial effects on health. The available questionnaires, according to the MD dietary pattern, include the assessment of moderate alcohol consumption; but some groups, such as young adults and pre-conceptional and pregnant women, are not allowed to consume it. The aim of this study was to validate a new short questionnaire (MedQ-Sus) excluding alcohol consumption, to measure the adherence to the MD and to evaluate the nutritional adherence to a sustainable diet. The Harvard validated questionnaire was used for the validation study. A total of 316 subjects (20 to 70 YOA) completed both questionnaires. A high Spearman correlation coefficient (rho = 0.69; p < 0.01) was found between the MedQ-Sus and Harvard scores; a statistically significant positive correlation was found for all eight food groups. The MedQ-Sus had a significant discriminative capacity between adherence and non-adherence to the MD (optimal cut-off point = 9.5, sensitivity 0.86, specificity = 0.65). A very high nutritional adherence to a sustainable diet was found in the subjects for olive oil (97%), dairy food (90%), fresh vegetables (89%), fish and fish products (73), fresh fruit (56%), and cereals and cereals products (42%). A very low adherence was found for legumes (22%) and meat and meat products (9%). The results showed MedQ-Sus is a valid and quick assessment instrument for the evaluation of the adherence to the MD in all population groups, and could also be useful to evaluate the nutritional sustainability of the diet.