Prediction of the Physicochemical and Nutraceutical Characteristics of 'Hass' Avocado Seeds by Correlating the Physicochemical Avocado Fruit Properties According to Their Ripening State

Innovative Postharvest Management for Hass Avocado at the Preclimacteric Stage: A Combined Technology with GABA and 1-MCP

Avocado (Persea americana Mill.) is a subtropical climacteric fruit with a limited shelf life due to its high sensitivity to low temperatures. Chilling injury (CI) produced by cold storage displays symptoms in avocado fruit such as irregular ripening, darkening of the mesocarp, hardening of vascular strands, lipid oxidation with "off flavors", and pitting and darkening of the skin, increasing weight loss. Accordingly, we studied the effect of γ-aminobutyric acid (GABA) and 1-methylcyclopropene (1-MCP) alone or in combination as postharvest treatments to maintain quality and to increase cold tolerance. Hass avocados were stored at 5 °C plus 5 days at room temperature. The results showed that the combined treatment improved fruit quality parameters as compared with control fruit and with those treated with only 1-MCP or GABA. The combined treatment delayed synergistically the postharvest ripening process. This delayed pattern was concomitant with a delayed ethylene pattern in GABA + 1-MCP or 1-MCP fruit batches. CI symptoms and electrolyte leakage were minimized in all GABA and 1-MCP fruit batches specifically in the combined treatment. For this reason, the synergistic effect of the combination of treatments may be recommended as an effective alternative strategy to prolong the postharvest quality of avocado during refrigerated storage.

A Functional End-Use of Avocado (cv. Hass) Waste through Traditional Semolina Sourdough Bread Production

In recent years, a main goal of research has been to exploit waste from agribusiness industries as new sources of bioactive components, with a view to establishing a circular economy. Non-compliant avocado fruits, as well as avocado seeds and peels, are examples of promising raw materials due to their high nutritional yield and antioxidant profiles. This study aimed to recycle avocado food waste and by-products through dehydration to produce functional bread. For this purpose, dehydrated avocado was reduced to powder form, and bread was prepared with different percentages of the powder (5% and 10%) and compared with a control bread prepared with only semolina. The avocado pulp and by-products did not alter organoleptically after dehydration, and the milling did not affect the products' color and retained the avocado aroma. The firmness of the breads enriched with avocado powder increased due to the additional fat from the avocado, and alveolation decreased. The total phenolic content of the fortified breads was in the range of 2.408-2.656 mg GAE/g, and the antiradical activity was in the range of 35.75-38.235 mmol TEAC/100 g (p < 0.0001), depending on the percentage of fortification.

Avocado seed by-product uses in emulsion-type ingredients with nutraceutical value: Stability, cytotoxicity, nutraceutical properties, and assessment of in vitro oral-gastric digestion

The avocado industry obtains 20-30% of the total by-products (peels and seeds). However, byproducts can be uses as sources of economic nutraceutical ingredients with functional potential. This work developed emulsion-type ingredients from avocado seed to evaluate its quality, stability, cytotoxicity, and nutraceutical properties before/after in vitro oral-gastric digestion. Ultrasound lipid extraction achieved an extraction yield of up to 95.75% compared with Soxhlet conventional extraction (p > 0.05). Six ingredients' formulations (E1-E6) were stable for up to day 20 during storage, preserving their antioxidant capacity and displaying low in vitro oxidation compared to control. None of the emulsion-type ingredients were considered cytotoxic according to the shrimp lethality assay (LC₅₀ > 1000 µg/mL). Ingredients E2, E3, and E4 generated low lipoperoxides' concentrations and high antioxidant capacity during the oral-gastric stage. The 25 min-gastric phase showed the highest antioxidant capacity and low lipoperoxidation. Results suggested avocado seed-derived could be used to develop functional ingredients with nutraceutical properties.

Tocopherol Accumulation and Temporal Expression Analysis of VTE1 and VTE5 Gene Family in Fruit of Two Contrasting Avocado Genotypes

α-tocopherol is found in high concentrations in avocado fruit mesocarp, however, its accumulation and genetic control during maturation and ripening has not been elucidated. Based in the relevance of VTE1 and VTE5 genes in tocopherol biosynthesis and aiming to determine the association between tocopherol accumulation and expression of tocopherol biosynthetic genes, gene expression of VTE1 and VTE5 were evaluated through the time during three developmental stages: before harvest at 100, 160 and 220 days after flowering (DAF) and after harvest (220 DAF + 5) in two contrasting avocado genotypes (San Miguel and AVO40). San Miguel reached the highest levels at 220 DAF, whereas AVO40 increased α-tocopherol only after ripening (220 DAF + 5). A genome-wide search for VTE1 and VTE5 allowed to identify one and three genes, respectively. Both genotypes showed contrasting patterns of gene expression. Interestingly, AVO40 showed a highly positive correlation between α-tocopherol levels and gene expression of VTE1 and all VTE5 variants. On the other hand, San Miguel showed only a positive correlation between α-tocopherol level and VTE1gene expression.

Biological Evaluation of Avocado Residues as a Potential Source of Bioactive Compounds

Avocado seed and peel are the main by-products from avocado industrialisation, and account for nearly 30% of fruit weight. Although they are usually discarded, their high phenolic content has been deeply associated with several nutritional and functional benefits. Thus, for a comprehensive analytical evaluation of both semi-industrial extracts, various steps have been developed: tentative characterisation and quantification of the phenolic composition using HPLC-ESI-qTOF-MS, determination of TPC and antioxidant activity by Folin–Ciocalteu, FRAP, TEAC and ORAC methods, evaluation of scavenging capacity against different ROS and measurement of the enzymatic inhibitory potential against potentially harmful enzymes. Finally, their bioactive potential was tested in a human platelet model where antiaggregatory activity was measured. Hence, 48 different compounds were identified, where flavonoids and procyanidins were the most representative groups. The higher TPC was found in avocado peel extract (190 ± 3 mg/g), which showed more antioxidant power and more capacity to decrease ROS generation than seed extract (60 ± 2 mg/g). In addition, both extracts showed enzymatic inhibition, especially against hyaluronidase, xanthine oxidase and acetylcholinesterase. Lastly, avocado peel was proven to inhibit platelet aggregation with significant results at 1, 0.75 and 0.5 mg/mL, where the extract showed reducing effects on agonists’ expression such as p-selectin or GPIIb/IIIa complex. These results demonstrate that both semi-industrial extracts—above all, avocado peel—have an interesting potential to be exploited as a natural by-product with antioxidant properties with multiple applications for the prevention of different pathologies.

Bioactive and Physicochemical Properties of Exotic Fruit Seed Powders: Mango (Mangefiera indica L.) and Rambutan (Nephelium lappaceum L.) Obtained by Various Drying Methods

Exotic fruits, which are becoming more and more popular in European countries, contain seeds, which are an unused and useless byproduct of fruit processing. Research conducted in recent years suggests that these unused waste products can be a source of nutrients and bioactive compounds in much more concentrated amounts than those found in the flesh of the fruit. Research on the physicochemical properties and the content of bioactive compounds in fruit seeds may allow the assessment of the possibility and purposefulness of their wider application in the production of functional food. Therefore, the aim of this study was to determine the physicochemical and bioactive properties of exotic, tropical fruit seed powders, such as mango (Mangefiera indica L.) and rambutan (Nephelium lappaceum L.) seeds, obtained by convective drying (CD) and sublimation drying (FD). In the tested powders, the water-holding capacity and water solubility were determined, the color was measured using the ‘electronic eye’ instrumental method, the taste profile was determined using the ‘electronic tongue’, and the content of selected bioactive compounds—such as tannins (titration method), total polyphenols and antioxidant activity was also determined using the spectrophotometric method. It was found that the studied powders were characterized by low water-holding capacity (1.2–1.6 g/1 g of powder), low solubility in water (9.5–17.4%), neutral color and varied taste profile, depending on the origin of the tested powder. Rambutan seed powders were characterized by a more bitter taste with a higher umami-flavor intensity compared to mango seed powders, which showed a more intense acidic and sweet taste. The conducted research shows that the applied methods of powder production, i.e., drying (to similar aw values) by convection vs. sublimation, had a much greater impact on changes in the content of bioactive compounds than on the tested physicochemical parameters. The freeze-dried seed powders were characterized by a higher content of polyphenolic compounds and a higher antioxidant activity than convection-dried seed powders. Considering the high content of polyphenols and high antioxidant activity, the studied powders may find applications in the production of dietary supplements and in the design of functional foods. Due to the low water solubility index, mango and rambutan powders can be used in the design of products where particle sensitivity is indicated. The use of the investigated exotic fruit seed powders, i.e., mango and rambutan, may not only be beneficial for nutritional reasons, but also may contribute to the reduction of post-production waste, in line with the recently widespread “zero waste” trend.

In vitro Bioaccessibility of Proteins, Phenolics, Flavonoids and Antioxidant Activity of Amaranthus viridis

The aim of this study was to investigate the chemical composition, mineral content and report the effect of gastrointestinal digestion on the proteins, phenolics, flavonoids and antioxidant activity of morphological parts of Amaranthus viridis (AV). The macronutrients found in the greatest quantity were proteins (leave, inflorescence and seeds) and fiber (roots and stem). The main minerals were calcium, potassium, iron and zinc. All the plant parts showed total phenolic (TPC) and total flavonoid (TFC) compounds that were correlated with antioxidant capacity (DPPH, ABTS and FRAP); the leaves and inflorescence presented the greatest potential. The antioxidant compounds from the leaves, inflorescence and roots decreased after static in vitro digestion, while the TPC and TFC of the digested seeds increased by more than 55%. Approximately 90% of the protein content was bioaccessible. To the best of our knowledge, for the first time, the bioaccessibility of proteins, phenolics, flavonoids and antioxidant activity of the leave, inflorescence, seeds, roots and stem from AV were reported. Taking into consideration the excellent nutritional properties, the morphological parts of the plant can be potentially explored as a source of protein, fiber, minerals and antioxidant compounds.