Search

The impact of cultivar, harvest time, and crop season on olive fruit characteristics and olive oil quality and minor components composition is assessed for super‐high‐density "Arbequina", "Arbosana", and "Koroneiki" in California, United States, during 2016, 2017, and 2018. Fruit oil content reaches a plateau in November for "Arbequina" and "Arbosana," while the accumulation rate keeps constant until early December for "Koroneiki." Free fatty acids, diacylglycerols, pyropheophytins, and ΔK are not affected by any of the considered factors. Peroxide value, K232, and K270 decreases with harvest time. Chlorophylls content decreases with harvest time, more rapidly in "Arbequina" and "Arbosana" than in "Koroneiki". Cultivar is the main factor affecting the fatty acid profile. "Koroneiki" has the highest oleic acid content, followed by "Arbosana" and "Arbequina." Phenolic and volatile compounds are profoundly affected by cultivars and crop seasons, suggesting the relevance of these factors on the sensory and nutritional properties of virgin olive oil from super‐high‐density cultivars. Stepwise linear discriminant analysis allows selecting suitable markers among fatty acids, phenolic, and volatile compounds for cultivar, crop season, and harvest time discrimination. Practical Application: This paper constitutes the first report of a multiyear study considering quality and composition in bioactive compounds of super‐high‐density "Arbequina," "Arbosana," and "Koroneiki," planted in California, USA. This information helps processors understand the differences in oil made from the most common super‐high‐density cultivars along harvest times and for growers to make planting and harvesting decisions. [ABSTRACT FROM AUTHOR]

Hammer mill crushing variables and malaxation time are studied through a two‐level factor factorial experimental design in order to assess the impact of these parameters and their interactions on olive oil extraction efficiency, overall quality, and minor components composition. Extraction efficiency is mainly affected by the interaction between hammer mill grid size and malaxation time; higher yields are obtained when smaller grid sizes are combined with longer malaxation times. Regarding quality parameters and volatile compounds, the main effect is caused by malaxation time. Phenolic compounds are affected by all the studied parameters, hammer mill grid size has the highest impact on their final concentration in the oil. The results show that the effect of malaxation time on the studied variables is conditioned by the crushing parameters used during paste preparation. Practical Applications: Traditionally, the impact of processing variables on olive oil composition has been studied following a one‐variable‐at‐a‐time approach. A factor factorial experimental design allows the interactions among crushing conditions and malaxation time to be determined, as well as the individual contributions to extraction efficiency and minor components composition of these variables. Considering a more holistic approach to the study of olive oil extraction might provide processors with a wider spectrum of tools to maximize both yield and quality during olive oil processing. Interaction of grid size, rotor speed, and malaxation time during olive oil extraction affects extraction efficiency, volatiles, and phenolics. [ABSTRACT FROM AUTHOR]

Crushing of the olive fruit is the first operation for olive oil extraction. The hammer mill is one of the most popular devices used in modern facilities due to its easy maintenance and high product output. The effect of hammer mill rotor speed and sieve design, including screen size and screen open area on extraction yield, overall quality and minor component composition, is evaluated at the laboratory scale. Quality parameters such as free fatty acids (FFA), peroxide value (PV), and UV absorbances (K232, K270, and ΔK) are unaltered by crushing parameters. Extraction efficiency, chlorophylls content, total phenol content, 3,4‐DHPEA‐EDA, and p‐HPEA‐EDA increase with faster hammer mill rotor speed and smaller screen size. Volatiles (E)‐2‐hexenal, hexanal, 1,5‐hexadiene‐(3,4)‐diethyl, 3‐ethyl‐1,5‐octadiene, and (E)‐2‐hexenol are only affected by screen size. Screen open area is found to be a relevant factor regarding extraction efficiency, chlorophylls, total, and individual phenols as well as the volatile compounds 1,5‐hexadiene (3,4)‐diethyl, 3‐ethyl‐1,5‐octadiene, hexanal, and (E)‐2‐hexenal. Practical Application: It is found that screen open area is a relevant factor regarding extraction efficiency, chlorophylls, total and individual phenols and volatile compounds, in addition to the screen size and rotor speed. This is useful information for millers who are interested in optimizing extraction efficiency as well as the minor compounds of extra virgin olive oil. Hammer mill sieve design impacts extraction efficiency, chlorophylls, total and individual phenols, and the volatile compounds during laboratory‐scale extraction of olive oil. [ABSTRACT FROM AUTHOR]