Effect of temperature on soluble invertase activity, and glucose, fructose and sucrose status of onion bulbs (Alliumcepa) in store

Abstract

The activity of soluble invertase, and the variation in glucose, fructose and sucrose contents in onion bulbs (Allium cepa) during long-term storage at 10 degrees C and 20 degrees C were investigated. Invertase activity increased progressively after 8 weeks to 0.084 and 0.092 nkat/g fresh weight (FW), then sharply to 0.29 and 0.35 nkat/g FW at 20 degrees C and 10 degrees C, respectively, and remained high during 5 weeks. Then, activity decreased abruptly to 0.039 and 0.041 nkat/g, and remained low during the last 8 weeks and close to that observed initially. Glucose increased to 17.73 and 14.62 mg/g FW after 4 weeks at 20 degrees C and 10 degrees C, respectively, then decreased sharply between week 5 and week 7 to 4.13 and 4.91 mg/g FW, respectively, and remained rather stable ranging from 9 and 10 mg/g FW at both temperatures. Fructose showed a similar pattern and was 14.8 and 21.68 mg/g FW at 20 degrees C and 10 degrees C, respectively. Between week 10 and week 24, fructose ranged from 5 and 6 mg/g FW, and from 6 and 7 mg/g FW at 20 degrees C and 10 degrees C, respectively. Sucrose increased to 19.63 and 14.43 mg/g FW at 20 degrees C and 10 degrees C, respectively, decreased during 3 weeks, and then increased randomly from 5.69 to 9.42 mg/g FW at 20 degrees C, but remained in a steady state at 10 degrees C ranging 5.03 +/- 0.78 mg/g FW. During the last 6 weeks, the sucrose content was higher at 20 degrees C than at 10 degrees C. The fructose-glucose ratio varied during the first 8 weeks but remained at a steady level during the last 16 weeks. The (glucose+fructose)/sucrose ratio increased randomly at 10 degrees C, whereas at 20 degrees C the ratio increased during 10 weeks then decreased progressively during the final 14 weeks.

Quantitative analysis of flavonoids, sugars, phenylalanine and tryptophan in onion scales during storage under ambient conditions

“…Our repeated experiments on this point concludes sucrose is deviated from glucose and fructose. Further, the metabolism of sucrose into glucose and fructose catalysed by the enzyme invertase is largely independent of temperature and depends on the physiology of onion (Benkeblia et al 2004). Also, a similar behavior has been reported by Chope et al 2007a, where the trend of fructose and glucose correlative and the sucrose level varying differently.…”

“…Our results are in contrast with , where they noticed continuous decrease in quercetin glucosides during the storage of 168 days. Previously it was reported Benkeblia et al (2004) total phenolic content of inner buds for control sample (stored at 18°C) increased during 5th week and then decreased progressively during last 3 weeks of storage. On the contrary, Gennaro et al (2002) reported that for flavonoids in red onion tends to decrease after 6 weeks storage especially at 20°C and 30°C.…”

In Vitro Efficacy of Diallyl Sulfides against the Periodontopathogen Aggregatibacter actinomycetemcomitans

“…It has been previously reported that heat treatment of garlic extract resulted in the highest antibacterial activity and that this positively correlates with increases in DAS content as evidenced by GC and mass spectrometric analyses (11,15,42,65). Recently, the inhibitory mechanism of DAS against Listeria monocytogenes and E. coli O157:H7 was demonstrated by Fourier transform infrared (FT-IR) and Raman spectroscopy (54).…”

“…Garlic has been used as a medicine since ancient times and has long been known to have antibacterial, antiviral, antifungal, antialgal, antiproteolytic, anticancer, antithrombotic, antiatherosclerotic, antioxidant, and immune modulation properties (4,5,12,16,45,58,59,60,66,69,70,77). Recently, garlic extract was shown to have effective broad-spectrum antimicrobial activity (11,15,21,44,62,74), including activity against oral bacteria (8). The main antimicrobial constituent of garlic has been identified as the oxygenated sulfur compound allicin.…”

Food Biochemical Study on Fructans and Related Synthesis Enzymes

“…Post-harvest metabolism of fructo-oligosaccharides in onion and asparagus plants Alongside the studies on fructo oligodsaccharide accumulation during seed development 36) and bulbing, 37) we also studied the main enzyme activities involved in the synthesis and the hydrolysis of fructo oligosaccharides during the pre harvest 38) (growth), and post harvest 38,39) (storage) life of onion bulbs and asparagus spears, 40) although present knowledge is insufficient to clearly explain the mechanisms triggering enzymes or the mechanisms by which fructo oligosaccharides contribute to bulb quality and perishability. 39) Storage of onion bulbs for 6 months causes a decrease 41,42) in the contents of glucose, fructose and sucrose, as shown by Fig. 15.…”