Determination of ‘Hass’ avocado ripeness during storage by a smartphone camera using artificial neural network and support vector regression

Effects of Delaying the Storage of 'Hass' Avocados under a Controlled Atmosphere on Skin Color, Bioactive Compounds and Antioxidant Capacity

During ripening, 'Hass' avocado skin changes from green to purple/black. Low-temperature storage with a controlled atmosphere (CA) is the most widely used method for avocado storage; however, few studies have simulated this technology and considered the days of regular air (RA) storage prior to CA storage. Herein, the effect of delaying the storage of 'Hass' avocado (>30% dry matter) in a CA was examined. Long-term storage conditions (5 °C for 50 days) corresponded to (i) regular air storage (RA), (ii) CA (4 kPa O2 and 6 kPa CO2) and (iii) 10 days in RA + 40 days in a CA and (iv) 20 days in RA + 30 days in a CA. Evaluations were performed during storage and at the ready-to-eat (RTE) stage. Skin color remained unchanged during storage, but at the RTE stage, more color development was observed for fruits stored under CA conditions, as these fruits were purple/black (>50%). At the RTE stage, the anthocyanin content increased, and compared to fruit under RA, fruit under a CA contained a five-fold greater content. A 20-day delay between harvest and CA storage increased the fruit softening rate and skin color development after cold storage, reducing the effectiveness of CA as a postharvest technology for extending storage life.

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

Vegetal wastes are currently a source of pollution due to the excess of organic compounds in the environment. Seeds are the main by-product of the avocado industry and represent 16-22% of the total weight and it is considered a waste without applications. Despite the seed stands out for its high content of phenolic compounds, lack of knowledge regarding of the best processing state using non-invasive and short-time methods are required to take advantage of these nutraceutical compounds. This research aimed to find correlations from physicochemical analysis, color, hardness, and firmness of the whole avocado seeds with its nutraceutical properties as long as the ripeness increased, providing information for further industrial use of this waste. The results indicated that 'Hass' avocado fruit ripening positively correlates with the improvement of the physicochemical parameters involved in the fruit processing and the increase of nutraceutical compounds in the seed. The ripeness process decreased moisture (%) and hardness (N) parameters in the seeds (27.69 and 16.4%, respectively), facilitating its processing. Moreover, the ripening increased the antioxidant capacity by DPPH* around 7%, due to the concentration of phenolic compounds in the seed. Seed's phenolic compounds were positively correlated with the Hue angle at increasing ripeness, becoming a potential physicochemical indicator for the industry. The prediction of changes in nutraceutical compounds and physicochemical properties, as ripening occurred, may reduce analysis times, processes, and guidance to use avocado seeds as a by-product. These results facilitate the seed processing and open up opportunities for its use in the industry.