Physiological changes during postharvest senescence of broccoli

Abstract

The objective of this work was to determine the early physiological changes throughout shelf life of fresh broccoli (Brassica oleracea L. var. italica) cv. Piracicaba Precoce at 25ºC and relative humidity of 96% in the dark until complete senescence. Head inflorescences showed lack of turgidity and commercial value when weight loss reached up to 5%, coinciding with 48 hour after harvest. Chlorophyll content was stable until 24 hours after harvesting; afterwards, an intense degradation phase took place. At 72 hours, total head yellowing was observed when chlorophyll content dropped to 30% of its initial content. Peroxidase activity increased by 1.4 fold during the first six hours, dropping to its lowest level approximately 24 hours after harvesting. However, from this time on, an increment of activity was observed until 72 hours. At 24 hours after harvesting, respiration was reduced by 50%. At later stages of senescence, respiration of florets was stable, but in a lower level than that determined at harvest. Sharp reduction of starch and reducing sugars was observed within 24 hours after harvesting, followed by continuous period of decline in starch and non-reducing sugars.

Changes of the colour, total sugar content and respiration rate of broccoli heads during short-term storage

“…NPT.2015.4.56 6 mained almost at the same level (about 400 mg CO2 per 1 kg·h -1 ) from 10 to 24 h of storage. The differences between our findings and those reported by King and Morris (1994), and by Finger et al (1999) may have resulted from the different size of the broccoli heads, which were measured. This correlation was also confirmed by Tian et al (1995), who observed that the increase in the respiration rate during the first 24 h after harvesting was inversely proportional to the size of the broccoli head.…”

“…After 9 h after beginning of the experiment the respiration rate was 53-84% of initial values. In the research by Finger et al (1999) the respiration rate decreased by 50% during the first 24 h of storage at the temperature of 25°C, and then it increased slightly. King and Morris (1994) arrived at similar conclusions.…”

The influence of the broccoli (Brassica oleracea var. itálica)fill weigth on postharvest quality

“…The variations in enzymatic activity for each treatment were also observed, with eminence for the Control one, due to the physiologic stress and loss of membrane integrity [9]. For the other treatments, specially, PP4 and PP5, after the initial sharp reduction, a constant uniformity was observed.…”

“…During this experiment variations on enzymatic activity were also observed. The enzymatic activity increased sometimes and these variations probably occurred cause the disintegration of the membrane and degradation reactions, which produced hydrogen peroxide [9]. So there was an increase in peroxidase activity which eliminated that compound.…”

Integrated alkali pretreatment and preservation of wet lettuce ( Pistia stratiotes ) by lactic acid bacteria for fermentable sugar production

“…All pretreated biomass contained a relatively lower percentage of starch than the raw biomass. Since the reduction of starch was not affected by any treatment conditions, the decrease of the starch content might have been caused by natural degradation; the reduction of starch content during post-harvest period has also been found in many other plants [29]. The lignin content of pretreated biomass was only affected by the addition of NaOH (Table 2b).…”