Influence of fruit canopy position and maturity on yield determinants and chemical composition of virgin olive oil

Abstract

BACKGROUND: While both maturity and light exposure are important factors determining olive fruit physiology, the relationship between maturity, canopy position and optimal harvesting time has not been well-studied. To understand the interaction of these factors, olive fruits from upper and lower layers of the canopy were harvested from September to January. Maturity, moisture and fat content of the fruit as well as the quality and minor components of the oil extracted were measured. RESULTS:Lower light interception at the lower canopy positions resulted in differences in the fruits and oil extracted between canopy layers. Upper layer presented 60% of the overall production; fruit had one unit more of maturity index, 3% less moisture and 5% more fat content. Oil extracted from the upper layers presented higher concentration of oleuropein and ligstroside aglycone. Fruits from upper layers at maturity index of two had higher fat content and more total phenols in the oil extracted when compared with fruits from lower layer with the same maturity index. CONCLUSIONS: Differences in oil composition between layers do not correlate with differences in the fruit maturity index;instead, fruit position is a determining factor for physiological processes related to fruit growth and oil composition.brix, 16 dry matter 17 or fruit respiration. 18 Studies have also found that there are connections between fruit maturation and specific sterols and fatty acids present in the fruit pulp. 19 Additionally, non-destructive methods have been developed by measuring anthocyanin content in the peel 20 or using fruit external color and texture. 21 Olive oil quality parameters, such free fatty acidity, peroxide value, specific UV absorbances and sensory attributes have also been shown to change along fruit maturation. 22,23 Previous studies were performed to study how temperature, 24 incident light, 25,26 maturation or canopy position 6,7 in the fruit influence productivity and composition on the oils extracted. However, there is a lack of understanding on how canopy management can influence fruit maturation along harvest season in order to understand if there are possible interactions between these factors. Therefore, the aim of this research was to investigate the effect of fruit canopy position on fruit maturation and oil composition and to determine which parameters are determinant for the optimal harvesting time. MATERIAL AND METHODS Plant material and experimental designThe study was carried out at the Wolfskill Experimental Orchard Field Station from University of California, Davis (Winters, CA, USA) (38.502920, −121.977120). Trees of Arbequina cultivar of ten years old, managed under sprinkler irrigation were used in this experiment. The trees were trained to vase system (5 m × 6 m) with a single trunk with two main branches, oriented along the row, starting by 0.5 m height above ground. Two more couples of main branches were inserted at 150 and 230 cm above ground respectively. The average height of the trees was 3 m and the averag...

Tree Planting Density and Canopy Position Affect ‘Cerasuola’ and ‘Koroneiki’ Olive Oil Quality

“…'Cerasuola' fruit showed higher fat content at the upper than the lower canopy layers independent of planting density, whereas 'Koroneiki' fruit showed higher values in the upper layers only at HD. These observations agree with findings from previous studies showing that fruits from lower canopy positions accounted for approximately one-fourth of tree fruit production (26%) and oil yield (25.2%) [33], while fruits from the upper canopy layers showed the highest weight, ripening index, and oil content [12,26,32]. A possible explanation for a higher oil accumulation is that fruits from upper layers were more exposed to incident light which has been shown to increase the number of oil bodies inside the fruit mesocarp [39].…”

“…Fruits receiving more radiation showed the highest fruit weight, mesocarp oil content, maturity index, and total polyphenols in virgin olive oil [20]. Recently a study of 'Arbequina' also found that oil extracted from the upper layers presented higher concentration of oleuropein and ligstroside aglycone [12]. These compounds, besides having high antioxidant capacity, also contribute to the bitter and pungent flavor of the oil [21].…”

“…Marketing of high quality olive oils is based on the chemical and sensory attributes, which are strongly affected by genotype, environment, fruit maturity at harvest, and their interaction among other factors [7][8][9]. Previous studies evidenced that high quality olive oil requires harvesting olive fruit at the optimum time [10][11][12]. The rate of oil synthesis and the length of the oil accumulation period can be responsible for the final oil content in the olive fruit [13,14].…”

Virgin Olive Oils from Super‐High‐Density Orchards in California: Impact of Cultivar, Harvest Time, and Crop Season on Quality and Chemical Composition

“…Values were in the range 6.1–22.2 g per 100g for “Arbequina,” 8.6–21.7 g per 100g for “Arbosana,” and 7.7–24.3 g per 100g for “Koroneiki.” The low moisture content of “Koroneiki” resulted in higher oil content on a wet basis compared to “Arbequina” and “Arbosana.” While the rate of oil accumulation started to plateau in November for “Arbequina” and “Arbosana,” it continued to increase for “Koroneiki.” Fruit harvested by the beginning of December in the South of Spain, with comparable maturation indexes and moisture contents to the ones of this study, presented lower values of oil content on a wet basis in the range 20.0–21.6 g per 100g, not showing significant differences among cultivars. [ 9 ] Previously, our group had found that the maturation index did not correlate with fat accumulation in drupes from “Arbequina.” [ 22 ] Similarly, the same observation held true for “Arbosana” and “Koroneiki” as considerable differences in oil content were observed in a period where the maturation index did not change significantly, suggesting oil content as a better harvest predictor compared with the maturation index.…”

“…[9] Previously, our group had found that the maturation index did not correlate with fat accumulation in drupes from "Arbequina." [22] Similarly, the same observation held true for "Arbosana" and "Koroneiki" as considerable differences in oil content were observed in a period where the maturation index did not change significantly, suggesting oil content as a better harvest predictor compared with the maturation index.…”