Studies on the Sugar Accumulation and Carbohydrate Splitting Enzyme Levels in Post Harvested and Cold Stored Potatoes (original) (raw)
Related papers
Biochemical Behaviour of Potato Tubers during Storage
The study was planned to assess the status of sugar and starch content of two harvests in relation with seed storage. The present investigation was carried out with potato cultivar Kufri Himalini. Invitro developed plantlets were transplanted in field and tubers were harvested twice at monthly intervals i.e. July (90 DAP) and August (120 DAP). Potato tubers were stored for 120 days at ambient condition. Estimation of starch and reducing sugar were carried out at monthly intervals. Results found that both the harvest showed significant difference in starch content between different grades and storage time. The maximum starch content was recorded with larger size S1 (19.49%), medium size S1 (19.41%) harvest of 120 DAP and minimum value was recorded with small sized tubers S5 (13.84%) harvest of 90 DAP. Among two harvests, tubers of 90 DAP had no significant difference in total reducing sugar content between different grades and storage time whereas tubers of 120 DAP showed significant difference. The maximum value for reducing sugar was recorded with small size S5 (0.63%) followed by medium size tubers S5 (0.62%) harvest of 90 DAP. Quality of potato seed tubers depends on the sugar and starch content, which is depends on their maturity level. Early harvest i.e., 90 DAP showed higher starch conversion which was responsible for higher reducing sugar by which sprouting might be enhanced. So we can use early harvest, which reduces the storage time and also vigorous seed tubers will be available earlier for next planting season.
Food Science and Technology
Storage of tubers is vital for uninterrupted supply to potato chips/fries industry. Cold storage is preferred to maintain tuber quality. However, prolonged storage at low temperature results in cold induced sweetening (COS) leading to sugar accumulation and browning of chips. Slowing down the COS is of economic importance for potato industry. Screening of potatoes after cold storage for low sugar and invertase activity with exploration of best frying color was the aim of current study. Reducing sugars (RS), invertase activity and chips color were estimated after subjecting the tubers at 3°C and 7°C storage. Analytical techniques were adopted for quantification of RS and invertase activity while nine-point Hedonic scale was used for chips color evaluation. Highest invertase activity with maximum RS (mg 100-1 g) and dark brown chips were observed in Kuroda following the Santé (247.83), Asterix (216.73), Crozo (193.42), Hermes (171.57) and Lady Rosetta (134.07) after storage at 3°C. Low RS were found in tubers stored at 7°C with good frying color in Lady Rosetta (98.23) followed by Hermes (104.31) and Crozo (113.27). Conclusively storage temperatures have significant effect on quality of tubers in which 7°C proved best with less RS and invertase activity having good frying color.
Journal of Food Biochemistry, 2016
This study investigated the changes in carbohydrate metabolism in tubers of 11 Indian potato varieties stored at room temperature, 15C and 4C for 150 days to understand the development of cold-induced sweetening (CIS). Low-temperature storage negligibly influenced starch and maltose contents of the tubers but induced a significant increase of reducing sugars, total soluble sugars, fructose, glucose and hexoses : sucrose ratio, and a decrease of sucrose content was noticeable at 4C. A strong positive correlation was found between reducing sugars and total soluble sugars, and between fructose and glucose. The activity of β-amylase was considerably increased by storage at low temperature, and it weakly correlated with starch content. Also, the absence of maltose accumulation with increased β-amylase activity was observed. Acid invertase activity drastically rose at low temperature and strongly paralleled reducing sugars, glucose, fructose and hexose : sucrose ratio. The K. Jyoti variety was designated as CIS-tolerant and the K. Badshah variety as CIS-susceptible. PRACTICAL APPLICATIONS Development of cold-induced sweetening (CIS) is important for basic research and for potato-processing industry. This work allowed us to group 11 Indian potato varieties into low-sugar-forming and high-sugar-forming groups, to identify varieties suitable for processing immediately after harvest or short time storage and to identify varieties with high starch content suitable for starch extraction. Hence, it provides capital information to the industry about varieties with good starch yield, which can be cold-stored without drastic sugar increase, and to breeders for searching genes of resistance to CIS in Indian potatoes. This study also demonstrated that during CIS development in these varieties, acid invertase is the key enzyme, β-amylase is not the main enzyme of starch degradation and there is possible significant activity of maltase in potato tubers. These observations pave the way through biotechnology work to develop new potato varieties which can cope with this postharvest problem.
Journal of Animal & …, 2009
The cultivar, harvest time and storage method affect reducing sugars content of potato, which in turn influences the processing quality of French fries. Eight Kenyan potato cultivars (Tigoni, Desiree, Dutch Robyjn, Kenya Karibu and Kenya Sifa) and three advanced clones (393385.47, 391696.96 and 393385.39) were studied to determine their suitability for the chipping industry, and to determine the effect of harvesting time and storage conditions on their processing quality. Early harvesting of tubers resulted in significantly higher (P≤0.05) levels of reducing sugars (0.33-0.45 %) than harvesting at maturity (0.15-0.37 %). No significant change (P>0.05) occurred in the reducing sugar content when tubers were stored at ambient air conditions (15-19 o C/86-92 % RH) for up to 12 weeks. In cold storage (4 o C/95 % RH), tubers of all the cultivars accumulated more reducing sugars and none was suitable for chipping even after reconditioning for up to 3 weeks at ≥15 o C. Cold stored potatoes may, however, be suitable for mashing and or general home use. The information obtained in this study will inform Kenyan farmers and processors regarding the appropriate harvesting time and storage conditions for potatoes produced for chipping.
2014
Total soluble sugar content and composition was studied by high performance liquid chromatography in four high dry-matter sweet potato cultivars at 3, 4, and 5 months maturity. Total soluble sugar consisted of sucrose, glucose, and fructose, ranging from 4.10–10.82 g/100 g (dry-weight basis). At harvest, there were significant differences in total soluble sugar due to maturity (p < 0.001) and cultivar (p < 0.05). The highest total soluble sugar contents were in 5-month samples at harvest (7.36–10.34 g/100 g) and 4-month samples after short-term storage under tropical ambient conditions (8.66–10.82 g/100 g). Estimated amylase enzyme activity varied significantly with harvest age (p < 0.05). Although reducing sugar contents were low, fructose levels in 5-month samples increased considerably after storage.
Tuber starch amylose content is associated with cold-induced sweetening in potato
Cold-induced sweetening (CIS) is the accumulation of reducing sugars in potato tubers at low storage temperatures. It is undesirable because it results in dark fry products. Our study evaluated the relationship between genetic resis- tance to CIS and two starch parameters, amylose content and starch granule size. We found that the amylose content in four CIS-resistant varieties was higher than that in five susceptible varieties. Amylose content was influenced not only by variety but also storage, production year, and field location. How- ever, interactions between amylose content and environmental variables were not detected. In contrast, starch granule size was not associated with CIS resis- tance. No effect of storage on starch granule size was detected, and interactions among variety, production year, and field location were observed. Tuber starch amylose content should be considered a source of variability for CIS.
Plant Cell and Environment, 1998
The onset of sugar accumulation in cold-stored potato tubers coincides with an activation of sucrose phosphate synthase (SPS) and the appearance of a new form of amylase ). To provide more evidence that these changes are involved in the regulation of cold-induced sugar accumulation we have compared the temperature dependence of sugar accumulation with the temperature dependence of changes in SPS and amylase activity. To do this, we investigated: sugars and metabolites; SPS activity, protein and transcript; invertase activity; and amylolytic activity and amylase forms, during the first 10 d after transferring tubers from room temperature to 3, 5, 7, 9 and 11°C. After 10 d there was negligible accumulation of sugars at 11, 9 and 7°C, and a large accumulation at 5 and 3°C. Activation of SPS was assayed by comparing activity in an assay with limiting substrates and phosphate and an assay with saturating substrate concentrations. The activation state increased slightly at 7°C, 3-to 4-fold at 5°C and 5-to 6-fold at 3°C. The cold-induced change in the kinetic properties of SPS was accompanied by the appearance of a new form of SPS with a slightly higher apparent molecular weight, and by an increase of the SPS transcript. The changes in SPS protein and transcript showed the same temperature dependence as the changes in the kinetic properties. Total starch hydrolysing enzyme activity was unaltered at 7°C, increased at 5°C and increased further (up to 7-to 8fold) at 3°C. The increase in amylolytic activity correlated with the appearance of a new amylase band on zymograms. Acid invertase activity showed a similar increase at 3, 5, and 7°C, and it did not correlate with the total sugar accumulation. The cold-induced accumulation of sugar can be reversed by transferring tubers back to warmer temperatures. We compared the decline of sugar levels with the changes of SPS, amylolytic activity and metabolites at various times (up to 14 d) after transfer of tubers from a 4°C storage (for 14 d) back to 20°C. SPS activation state is reversed and the cold-induced form of SPS virtually disappears during the first 2-4 d at 20°C. The cold-induced amylase activity also vanishes within 2-4 d.
Screening Potato Cultivars for Low Sugar Accumulation During Storage at Various Storage Temperatures
Pakistan Journal of Agricultural Sciences
Low sugars and light frying color are key traits to be observed during storage while assorting the potatoes for chips/fries preparation. Selecting the best cultivars reflects an important element for effective and economical processing by the industry. Six commercial potato cultivars were selected to evaluate their behavior and chipping potential regarding sugar accumulation during storage for a period of 160 days at various temperatures (3, 7 and 11°C). All the temperatures posed significant effect on sugar contents during storage however, high sugar accumulation was noticed at 3°C for all the cultivars ranged from 29.03 to 255.38 for glucose, 26.78 to 253.11 for fructose and 55.33 to 114.45 mg100-1 g fresh weight for sucrose. Storage at 11°C had least effect on sugar accumulation than 3°C and 7°C. Chips color was used as an index to evaluate the processing quality as well as sugar accumulation. At the end of storage, sugar accumulation and chips color were found in order of (low to high) Lady Rosetta < Hermes < Crozo < Asterix < Santé < Kuroda. Consequently, significant variability among the cultivars was observed whereas Lady Rosetta (golden yellow), Hermes (slightly yellow) and Crozo (yellow) were found to be the most suitable cultivars for fries/chips preparation.
Simple sugars, oligosaccharides and starch concentrations in raw and cooked sweet potato
Journal of Agricultural and Food Chemistry, 1986
Compositions of the soluble sugars extracted with 70% ethanol from five raw and five cooked Philippine sweet potato tubers were analyzed by HPLC. The sum of glucose, fructose, and sucrose accounted for 85-96% and 1744% of the total soluble sugars identified in the extracted fractions of raw and cooked samples, respectively. Verbascose was present only in trace amounts, and stachyose was not detected in any of the samples. Starch content of raw and cooked samples determined enzymatically ranged from 33 to 73% and 32 to 61%. Starch degradation products, maltose and maltotriose, present in the cooked samples, coeluted with cellobiose and raffinose, respectively. GC analysis or amylase pretreatment of the extracted sugar solution before HPLC analysis revealed that the tubers contained 0.2344% cellobiose and negligible raffinose. Unlike legumes, the concentrations of indigestible oligosaccharides in sweet potato were too low to account for the flatulence that accompanies ingestion of sweet potatoes as a staple food.
Screening potato wild species for low accumulation of reducing sugars during cold storage
Electronic Journal of …, 2009
Tubers of 101 clones of 24 potato wild species were screened for accumulation of reducing sugar during cold storage at 4°C after 3 months of storage. Significant difference in reducing sugar content was observed between and within species. Elite clones with acceptable limit of reducing sugars were identified from different wild species. Solanum spagazzinii and S. sparsipilum had more number of clones with minimum reducing sugar content after cold storage. Some identified clones with less reducing sugars after cold storage were SS Nos.