Time of day for harvest and delay before processing affect the quality of minimally processed baby spinach

摘要

The objective of this study was to evaluate if time of day for harvest and delay before processing affected the quality of baby spinach. Three times of the day for harvest (8:30,13:00 and 17:30 h as H1, H2 and H3, respectively) and three times of delay before processing (DP) (3, 24 and 48 h as DP3, DP24 and DP48, respectively) were studied. Two trials were conducted, one in January and another in April corresponding with winter and spring seasons. Photosynthetic and transpiration rates of baby spinach just before harvest were the highest at midday (H2), coincident with the highest solar radiation and vapor pressure deficit. In winter, the leaf water content was the highest in H1 and H3, while in spring leaves harvested early in the morning (H1) showed the highest leaf water content and more vivid color measured as Chroma. The differences observed were maintained during storage only in spring. Respiration rates did not show differences among harvest times in winter while in spring, respiration rate increased with the progress of harvest time (HT), particularly with shorter DP (DP3 and DP24). Moreover, visual quality of minimally processed baby spinach did not show significant differences among HT in winter, while in spring, the visual quality decreased when HT was advanced. The DP did not affect most of the parameters evaluated during storage, except the decrease in the respiration rate and the increase in the microbiological counts, psycrotrophs and Pseudomonas, when DP was increased. Results showed the same tendency for the leaf water content, color, respiration rate and visual quality of baby spinach after storage. Therefore, the best visual quality obtained in H1 corresponded with higher leaf water content and color saturation and a lower respiration rate. According to these results, minimally processed baby spinach could be harvested any time of the day in winter, while it is recommended to harvest it early in the morning in spring. Minimally processed baby spinach can tolerate a delay to processing of at least 48 h without evident symptoms of quality loss. (C) 2015 Elsevier B.V. All rights reserved.