The antioxidant activity and the chemical composition of methanol extracts from peel and pulp belonging to two species of Tunisian prickly pears Opuntia ficus indica (spiny and thornless forms) and Opuntia stricta have been studied. The antioxidant capacity was measured by DPPH radical scavenging activity. The total phenolic compound (TPC) and the total flavonoid content were determined by the Folin–Ciocalteu method and colorimetric method, respectively. The phenolic compounds were identified and quantified by high-performance liquid chromatography (HPLC) coupled with an electrospray ionization mass spectrometry (ESI-MS). The results showed that O. stricta fruits present the best antioxidant activities than the two forms of O. ficus indica, while the TPC was more important in O. ficus indica than in the O. stricta fruits. The peels have higher flavonoids than pulp, and the thornless variety has more flavonoid than the spiny. The RP-HPLC and ESI-MS analysis detected two classes of phenolic compounds and betalain pigments. Isorhamnetin derivatives are the dominant flavonol glycoside identified in O. ficus indica (spiny: 65.25 μg·g−1; thornless: 77.03 μg·g−1) and O. stricta peels (19.22 μg·g−1).

Red-fleshed apples can be used for the production of innovative products such as rosé juices and ciders. Phenolic compounds including procyanidins (i.e., condensed tannins) and anthocyanins were quantified in the fruits and juices of a red-fleshed apple cultivar by chromatography coupled to UV-visible and mass spectrometry. Juice color was characterized by colorimetry. The influence of oxygen, pH, sulfites, ascorbic acid, and copper on the color stability of the juice was studied in an experimental design. Fruits were rich in polyphenols (0.5 g/100 g FW), with anthocyanins and procyanidins accounting for 9 and 73% of total polyphenols, respectively. Extractability of anthocyanins in the juice was 26%. Juice storage under air atmosphere at 35 °C resulted in significant browning with the anthocyanin level decreasing up to 86% after 14 days. In contrast, color was stable for storage under argon atmosphere. Sulfites, ascorbic acid, and copper have only a slightly influence on color stability in those conditions.

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Exploring and deciphering the biodiversity of oil bodies (OBs) recovered from oilseeds are of growing interest in the preparation of sustainable, natural and healthy plant-based food products. This study focused on chia (Salvia hispanica L.) and camelina (Camelina sativa L.) seed OBs. A green refinery process including ultrasound to remove mucilage, aqueous extraction by grinding and centrifugation to recover OBs from the seeds was used. The microstructure, composition and physical stability of the OBs were examined. Confocal laser scanning microscopy images showed that chia and camelina seed OBs are spherical assemblies coated by a layer of phospholipids and proteins, which have been identified by gel electrophoresis. The mean diameters determined by laser light scattering measurements were 2.3 and 1.6 µm for chia and camelina seed OBs, respectively. The chia and camelina seed OBs were rich in lipids and other bioactive components with, respectively, 64% and 30% α-linolenic acid representing 70% and 53% of the total fatty acids in the sn-2 position of the triacylglycerols, 0.23% and 0.26% phospholipids, 3069 and 2674 mg/kg oil of β-sitosterol, and lipophilic antioxidants: 400 and 670 mg/kg oil of γ-tocopherol. Phenolic compounds were recovered from the aqueous extracts, such as rutin from camelina and caffeic acid from chia. Zeta-potential measurements showed changes from about −40 mV (pH 9) to values that were positive below the isoelectric points of pH 5.1 and 3.6 for chia and camelina seed OBs, respectively. Below pH 6.5, physical instability of the natural oil-in-water emulsions with aggregation and phase separation was found. This study will contribute to the development of innovative and sustainable food products based on natural oil-in-water emulsions containing chia and camelina seed OBs for their nutritional and health benefits.

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