Cold storage of ‘Manzanilla de Sevilla’ and ‘Manzanilla Cacereña’ mill olives from super-high density orchards

The Use of a Cooling Crusher to Reduce the Temperature of Olive Paste and Improve EVOO Quality of Coratina, Peranzana, and Moresca Cultivars: Impact on Phenolic and Volatile Compounds

A new technology used to reduce the temperature of olive paste was applied to the extra virgin olive oil (EVOO) mechanical extraction process. The performance of a cooling crusher that was able to counteract the thermal increase that occurs during olive fruit grinding was analyzed to evaluate the effects on the development of volatile compounds and the concentration of hydrophilic phenols in the final product. The volatile profiles and phenolic fraction of EVOOs extracted from three different cultivars (Coratina, Peranzana, and Moresca) were positively affected by the use of lower temperatures during the crushing phase. The volatile fractions showed increases in the total aldehydes, mainly related to the concentrations of (E)-2-hexenal, and reductions in the total alcohols, mainly due to 1-penten-3-ol, 1-hexanol and (Z)-3-hexen-1-ol contents. The use of a lower temperature reduced the level of oxidative processes, protecting the phenolic compounds in the Moresca and Peranzana EVOOs by 17.8 and 12.1%, respectively.

Effects of an integrated harvest system on the quality of olive fruit for small producers

Small producers confront specific challenges when they opt to produce high-quality olive fruit. Limited resources for investing in harvest machinery and manpower are the main reasons for continuing a traditional harvest method that puts the final product and its economic value at risk. This paper discusses the efficiency of an integrated harvest system as a possible solution to these specific challenges. The system is formed by a newly designed manual harvesting device and the use of a cooling room near the olive grove. Both systems were evaluated to assess their feasibility for optimum conditions before processing. The combined effect of the harvesting method and cold storage on the fruit characteristics (incidence of decay, skin color, weight loss, firmness, respiration, and ethylene production) was evaluated on three different varieties (‘Arbequina’, ‘Picual’ and ‘Verdial’) and four different storage times (0, 4, 8, and 14 days). The results indicate that the proposed harvesting method in combination with an appropriate cooling system offers an affordable alternative for obtaining fruit with the best physiological characteristics.

Effect of Temperature and Time on Oxygen Consumption by Olive Fruit: Empirical Study and Simulation in a Non-Ventilated Container

Fermentation processes within olive fruit jeopardize the quality of the extracted oil. Aeration, temperature, and time play a crucial role in attaining the critical threshold at which an aerobic respiration shifts towards anaerobic. In this work, the O2 consumption and CO2 production of olive fruit kept in a closed container at different temperatures (5–45 °C) were measured over 7 h. The data allowed us to describe the relationship between the temperature and the respiration rate as an Arrhenius function and simulate the oxygen consumption in the inner part of a container full of fruit with low aeration, considering the generated respiration heat over time. The simulation revealed that olives risk shifting to anaerobic respiration after 3 h at 25 °C and less than 2 h at 35 °C when kept in a non-ventilated environment. The results underline the irreversible damage that high day temperatures can produce during the time before fruit processing, especially during transport. Lowering, as soon as possible, the field temperature thus comes to the fore as a necessary strategy to guarantee the quality of the olives before their processing, like most of the fruit that is harvested at excessive temperatures.

Cold Storage and Temperature Management of Olive Fruit: The Impact on Fruit Physiology and Olive Oil Quality—A Review

Cold storage of olive fruit has been the subject of study for over more than 50 years. From the 1990s on, an increasing amount of knowledge is build-up about the impact of the conservation on the physiological response of the fruit as well as on the quality of the extracted oil therefrom. This review offers a comprehensive synopsis of this research, discusses the most important influential factors and summarizes the results on the influence of the studied parameters on both the fruit and the oil. Currently, changing climatic conditions, new harvesting techniques and a more demanding consumer market are triggering the need to broaden this strict focus on conservation. A more dynamic view on the effects of temperature from the moment the fruit is harvested up to the oil extraction process, reveals the necessity to manage this crucial influential factor more diversely. An overview of how this management can take form is structured through a focus on the different phases of the postharvest processing and the widely different harvesting scales. Future prospects of research are presented based on the actual state of the art of cold storage research as well as on the necessities that come forward from a broader fruit temperature management perspective.