Search

During the industrial processing of almond fruits, tons of almond skins are generated. Valorization of blanched almond skin wastes by recovering natural polyphenols using water, instead of organic solvents, for direct application of aqueous baths for dyeing of wool fabrics was studied in this work. The results showed that it was possible to recover polyphenols from almond skins and use them as a dye for wool fibres. Kinetics of extraction was modelled by using the diffusion-based Chrastil’s model and Peleg’s empirical model, obtaining excellent fit in both cases (R2 > 0.96). The amount of polyphenol extracted was enough to achieve correct direct dyeing with excellent washing, rubbing and perspiration fastness although the shades obtained were dull. Nevertheless, it was possible to achieve a better coloration by using ion(II) sulfate as the mordant resulting in dyeings with reasonable good washing and rubbing fastness.

Perceived as a healthy food, almond beverages are gaining ever-increasing consumer preference across nonalcoholic vegetable beverages, ranking in first place among oilseed-based drinks. However, costly raw material; time and energy consuming pre- and posttreatments such as soaking, blanching and peeling; and thermal sterilization hinder their sustainability, affordability and spread. Hydrodynamic cavitation processes were applied, for the first time, as a single-unit operation with straightforward scalability, to the extraction in water of almond skinless kernels in the form of flour and fine grains, and of whole almond seeds in the form of coarse grains, up to high concentrations. The nutritional profile of the extracts matched that of a high-end commercial product, as well as showing nearly complete extraction of the raw materials. The availability of bioactive micronutrients and the microbiological stability exceeded the commercial product. The concentrated extract of whole almond seeds showed comparatively higher antiradical activity, likely due to the properties of the almond kernel skin. Hydrodynamic cavitation-based processing might represent a convenient route to the production of conventional as well as integral and potentially healthier almond beverages, avoiding multiple technological steps, while affording fast production cycles and consuming less than 50 Wh of electricity per liter before bottling.

Antioxidant films based on poly(&epsilon, caprolactone) (PCL) containing almond skin extract (ASE) were developed for food packaging applications. The effect of ASE incorporation on the morphological, structural, colour, mechanical, thermal, barrier and antioxidant properties of the prepared films were evaluated. The structural, tensile and thermal properties of the films were not altered due to ASE addition. Although no significant differences were observed for the oxygen permeability of samples, some increase in water absorption and water vapour permeability was observed for active films due to the hydrophilic character of ASE phenolic compounds, suggesting the suitability of this novel packaging for fatty foods conservation. ASE conferred antioxidant properties to PCL films as determined by the DPPH radical scavenging activity. The efficiency of the developed films was evaluated by the real packaging application of fried almonds at different ASE contents (0, 3, 6 wt.%) up to 56 days at 40 &deg, C. The evolution of peroxide and p-anisidine values, hexanal content, fatty acid profile and characteristic spectroscopy bands showed that active films improved fried almonds stability. The results suggested the potential of PCL/ASE films as sustainable and antioxidant food packaging systems to offer protection against lipid oxidation in foods.

Blanched skins and blanching water, by-products of almond processing, were evaluated as potential ingredients of bakery products. The research included three phases: i) optimization of skin drying; ii) optimization of quali-quantitative determination of phenolic compounds, by comparing three extracting protocols; iii) assessment of the impact of by-products on the rheology of composite meals with wheat flour. Besides being less time-consuming, drying at 60 °C for 30 min lowered effectively skin moisture (7.86 g/100 g) and kept better odor notes (leafy and rancid odor scored 6.1 and 0.2, respectively), as well as higher content of phenolics (813.89 µg/g, with the most effective extracting method) and antioxidant activity (81.56 µmol Trolox/g), than sun-drying (8.09 g/100 g moisture; rancid odor scored 6.3; 317.06 µg/g phenolics; 59.23 µmol Trolox/g). Blanching water showed moderate leafy odor (score 3.3), slight sour odor (0.5), negligible rancid odor (0.2), and 917.46 µg/mL phenolics. Dried almond skins altered the alveograph and farinograph indices of dough at doses higher than 3 and 5 g/100 g, respectively, whereas blanching water did not cause significant changes. Therefore, almond skins could be used in products tolerating weak gluten network, such as cookies, whereas blanching water could be added to any bakery good.

A microwave-assisted extraction (MAE) procedure to isolate phenolic compounds from almond skin byproducts was optimized. A three-level, three-factor Box–Behnken design was used to evaluate the effect of almond skin weight, microwave power, and irradiation time on total phenolic content (TPC) and antioxidant activity (DPPH). Almond skin weight was the most important parameter in the studied responses. The best extraction was achieved using 4 g, 60 s, 100 W, and 60 mL of 70% (v/v) ethanol. TPC, antioxidant activity (DPPH, FRAP), and chemical composition (HPLC-DAD-ESI-MS/MS) were determined by using the optimized method from seven different almond cultivars. Successful discrimination was obtained for all cultivars by using multivariate linear discriminant analysis (LDA), suggesting the influence of cultivar type on polyphenol content and antioxidant activity. The results show the potential of almond skin as a natural source of phenolics and the effectiveness of MAE for the reutilization of these byproducts. We acknowledge the Spanish Ministry of Economy and Competitiveness for financial support (MAT-2011-28468-C02-01). A.V. thanks Conselleria de Educación (Spain) for ACIF/2010/172 Predoctoral Research Training Grant.

The goal of the present study was to quantify the rate and extent of polyphenols released in the gastrointestinal tract (GIT) from natural (NS) and blanched (BS) almond skins. A dynamic gastric model of digestion which provides a realistic simulation of the human stomach was used. In order to establish the effect of a food matrix on polyphenols bioaccessibility, NS and BS were either digested in water (WT) or incorporated into home-made biscuits (HB), crisp-bread (CB) and full-fat milk (FM). Phenolic acids were the most bioaccessible class (68.5% release from NS and 64.7% from BS). WT increased the release of flavan-3-ols (p < 0.05) and flavonols (p < 0.05) from NS after gastric plus duodenal digestion, whereas CB and HB were better vehicles for BS. FM lowered the % recovery of polyphenols, the free total phenols and the antioxidant status in the digestion medium, indicating that phenolic compounds could bind protein present in the food matrix. The release of bioactives from almond skins could explain the beneficial effects associated with almond consumption.

[EN] Reinforced poly(e-caprolactone) (PCL)/almond skin (AS) biocomposites were prepared by extrusion and injection moulding at different AS contents (0, 10, 20, 30 wt%) in order to revalorize this agricultural residue. AS particles were characterized by field emission scanning electron microscopy (FESEM), attenuated total reflectance infrared spectroscopy (ATR-FTIR) and thermogravimetric analysis (TGA). Hemicelluloses were the first compound thermally degraded (263 +/- 2 degrees C) followed by cellulose (330 +/- 5 degrees C) and lignin (401 +/- 3 degrees C) with a remaining residue of 20% which was associated to the fibre content present in AS. Mechanical, morphological, thermal, and water absorption properties; and enzymatic degradation using Pseudomonas lipase were evaluated for the obtained biocomposites. A significant improvement in Young's modulus with a gain of 73% at 30 wt% AS loading was obtained compared to neat PCL An increase in Shore D hardness and decrease in elongation at break and impact energy were also observed with increasing AS content caused by the reinforcement effect. Lower DSC thermal enthalpies and higher crystallinity were obtained for the biocomposites. Some decrease in thermal stability and higher water absorption values were also found with AS addition. Finally, the presence of AS retarded the enzymatic degradation of PCL, showing neat PCL higher weight loss after 25 days of study followed by PCL with 10 wt% AS. (C) 2016 Elsevier Ltd. All rights reserved., Authors would like to thank "Almendras Llopis S.A" for kindly providing the almond skin by-products as well as to Spanish Ministry of Economy and Competitiveness for financial support (MAT 2015-59242-C2-2-R). A. Valdes acknowledges Conselleria de Educacion (Spain) for ACIF/2010/172 Predoctoral Research Training Grant.

The aim of the present research was to determine the effect of almond skin extracts on herpes simplex virus 1 (HSV-1) replication. Drug-resistant strains of HSV frequently develop following therapeutic treatment. Therefore, the discovery of novel anti-HSV drugs deserves great effort. Here, we tested both natural (NS) and blanched (BS) polyphenols-rich almond skin extracts against HSV-1. HPLC analysis showed that the prevalent compounds in NS and BS extracts contributing to their antioxidant activity were quercetin, epicatechin and catechin. Results of cell viability indicated that NS and BS extracts were not toxic to cultured Vero cells. Furthermore, NS extracts were more potent inhibitors of HSV-1 than BS extracts, and this trend was in agreement with different concentrations of flavonoids. The plaque forming assay, Western blot and real-time PCR were used to demonstrate that NS extracts were able to block the production of infectious HSV-1 particles. In addition, the viral binding assay demonstrated that NS extracts inhibited HSV-1 adsorption to Vero cells. Our conclusion is that natural products from almond skin extracts are an extraordinary source of antiviral agents and provide a novel treatment against HSV-1 infections.

Poly(ε-caprolactone), PCL, degradation by microorganisms is a very interesting feature for its potential use in massive applications, such as food packaging. Blends of PCL with natural fibres, such as those from agricultural and food processing wastes, have proved effective by permitting a substantial reduction of the material costs, but also playing a role as reinforcement in mechanical properties. This study is focused on the evaluation of morphological, mechanical, thermal, barrier properties and degradation in composting environment of new bio-composites based on PCL and almond skin (AS) filler at different contents (0, 10, 20 and 30 wt%). Results showed a clear improvement in mechanical properties, corresponding to a gain in elastic modulus of 17% at 10 wt% particle loading. Lower melting and crystallization enthalpies and higher crystallinity values were obtained for bio-composites compared with neat PCL. Some decrease in thermal stability and increase in oxygen and water vapour barrier properties were also observed for composites with increasing filler content. PCL/AS composites showed higher biodegradability than pure PCL, which can be explained in terms of the depressed crystallization enthalpy of the polymer matrix and improved hydrophilicity. PCL-based composites reinforced with almond skin filler at 10 wt% loading have shown as promising environmentally-friendly materials for food packaging showing a high disintegration rate, increasing the added-value potential of agricultural wastes and reducing the packaging cost. Spanish Ministry of Economy and Competitiveness (MAT-2011-28468-C02-01). Arantzazu Valdés acknowledges Conselleria de Educación (Spain) for ACIF/2010/172 Predoctoral Research Training Grant.