Almond is characterized by its high nutritional value; although information reported so far mainly concerns edible kernel. Even though the nutritional and commercial relevance of the almond is restricted to almond meat; to date; increasing attention has been paid to other parts of this fruit (skin; shell; and hull); considered by-products that are scarcely characterized and exploited regarding their properties as valuable sources of bioactive compounds (mainly represented by phenolic acids and flavonoids). This lack of proper valorization procedures entails the continuation of the application of traditional procedures to almond residues that nowadays are mainly addressed to livestock feed and energy production. In this sense; data available on the physicochemical and phytochemical composition of almond meat and its related residues suggest promising applications; and allow one to envisage new uses as functional ingredients towards value-added foods and feeds; as well as a source of bioactive phytochemicals to be included in cosmetic formulations. This objective has prompted investigators working in the field to evaluate their functional properties and biological activity. This approach has provided interesting information concerning the capacity of polyphenolic extracts of almond by-products to prevent degenerative diseases linked to oxidative stress and inflammation in human tissues and cells; in the frame of diverse pathophysiological situations. Hence; this review deals with gathering data available in the scientific literature on the phytochemical composition and bioactivity of almond by-products as well as on their bioactivity so as to promote their functional application.

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Response Surface Methodology (RSM) was chosen to optimize the influence of solvent pH and relative proportion, and time of extraction, regarding polyphenols and radical scavenging capacity of almond (Prunus dulcis (Mill.) D.A. Webb) by-products (hulls, shells, and skins) from an almond orchard located in the North of Portugal (Lousa, Torre de Moncorvo). The RSM model was developed according to a Box-Behnken design and the optimal conditions were set for pH 6.5, 250.0 min, and 90.0% of food quality ethanol, pH 1.5, 235.0 min, and 63.0% ethanol, and pH 1.5, 250.0 min, and 56.0% ethanol for hulls, shells, and skins, respectively. The optimal conditions were obtained applying spectrophotometric techniques because of their versatility, while the chromatographic profile of extracts obtained when applied the optimal conditions indicated the presence of 3-caffeoylquinic acid, naringenin-7-O-glucoside, kaempferol-3-O-glucoside, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucoside, and isorhamnetin aglycone in hulls and skins.The model designed allowed the optimization of the phenolic extraction from almond byproducts, demonstrating the potential of these materials as sources of antioxidant compounds with potential industrial, pharmaceutical and food applications.

Purpose Several studies have demonstrated the properties of hydroxytyrosol, a phenolic compound present in olive oils and olives with a well-characterized impact on human health. Nevertheless, some knowledge gaps remain on its bioavailability and metabolism; overall concerning to the real rate per cent of absorption and biovailability of dietary hydroxytyrosol and the influence of the dietary food-containing hydroxytyrosol on it.Methods A double-blind study was performed including 20 volunteers who ingested 5 mg of hydroxytyrosol through diverse food matrices, to discover the influence on pharmacokinetics and bioavailability of HT metabolites (hydroxytyrosol acetate, 3,4dihydroxyphenylacetic acid (DOPAC), tyrosol, and homovanillic alcohol) of the distinct matrices by UHPLC-ESI-QqQ-MS/MS. ResultsThe HT pharmacokinetics after consumption of different food matrices was strongly dependent on the food matrix. In this aspect, the intake of extra virgin olive exhibited significantly higher plasma concentrations after 30 minutes of oral intake (3.79 ng/mL) relative to the control. Regarding the hydroxytyrosol bioavailability, the intake of extra virgin olive oil, as well as fortified refined olive, flax, and grapeseed oils provided significantly higher urinary contents (0.86, 0.63, 0.55, and 0.33 µg/mg creatinine, respectively) compared with basal urine, whereas hydroxytyrosol metabolites showed no significant changes. No differences were found between men and women. ConclusionsThe metabolic profile of hydroxytyrosol is influenced by the food matrix in which is incorporated, with the oily nature for the final bioavailability being relevant. Extra virgin olive oil was identified as the best matrix for this compound. The results described 3 contribute to the understanding of the relevance of the food matrices for the final absorption of hydroxytyrosol and hence, the achievement of the highest health protection potential.

Almond (Prunus dulcis (Mill.) D. A. Webb) production keeps an increasing trend worldwide, leading to augment in generation of harmful by-products that should be valorized as a source of bioactive phytochemicals with application in the development of new added-value products. The assessment of almond hulls and skins on their (poly)phenolic composition was developed upon two seasons, under five irrigation regimes, regarding total phenolics, flavonoids, and ortho-diphenols, as well as individual phenolic compounds analyzed by High-Performance Liquid Chromatography with Diode-Array Detection (HPLC-DAD). As functional tests, extracts were assessed on their radical scavenging activity in vitro and reducing power, and screened on their antimicrobial activity against multidrug resistant bacterial pathogens. The phenolic profile and antioxidant activities were evaluated in blancing water as well. Naringenin-7-O-glucoside and isorhamnetin-3-O-rutinoside were the most abundant phenolics in almond hulls and skins. Influence of irrigation treatments and season on phenolic content differed among by-products; hulls being more influenced by irrigation and skins by the agro-climatic conditions. The synthesis of individual phenolics was more influenced by season than treatment. According to the chemical and biological correlations, the presence of (poly)phenols seems to be responsible for the antioxidant and antimicrobial properties revealed. The knowledge generated upon the present work contributes to understand the variability of almond by-products composition attributable to seasonal and irrigation conditions, and to envisage valorization alternatives for these under explored residues and blanching water.