2 results
Phenolic compounds in minimally processed potato: Effect of cultivar, tuber storage time and thermal treatment
- Draženka Dite Hunjek, Zdenka Pelaić, Sandra Pedisić, Maja Repajić, Dino Jakupec, Verica Dragović Uzelac, Branka Levaj
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- Journal:
- Proceedings of the Nutrition Society / Volume 79 / Issue OCE2 / 2020
- Published online by Cambridge University Press:
- 10 June 2020, E479
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Potato (Solanum tuberosum spp.) is worldwide consumed mostly as table potato, but due to lifestyle changes, production of minimally processed potato (MPP) became an important sector of the food industry. From the health point of view, phenolic compounds as potatoes constituents are desirable, but also responsible for undesirable browning of peeled and sliced potato. The most abundant are phenolic acids such as chlorogenic acid, which is a substrate for enzymatic oxidation in the presence of phenolase and is responsible for browning processes. Its concentration in tubers depends on cultivar type as well as storage, and thereby can influence on shelf life of MPP. The purpose of the present study was to evaluate the effect of two potato cultivars of different tuber age on the phenolic content of MPP during 8 days of storage followed by thermal treatment. Cultivars Birgit and Lady Claire were selected and stored for 1 and 4 months in warehouse (8 °C/RH 95 %). Potatoes were washed, peeled, sliced and treated with 2 % sodium ascorbate solution for 3 minutes. After draining, MPP samples were vacuum packed in PE/PA bags and stored for 1, 5 and 8 days at 10 °C. After storage, samples of raw, boiled and fried MPP were freeze dried and phenolic content was determined by UPLC MS/MS. In all potato samples chlorogenic acid, catechin and epicatechin were determined, where chlorogenic acid predominated (almost 97 %).
Generally, lower phenolic content was determined in cv. Birgit samples. Comparing cultivars upon tubers age, total phenolic content (as sum of all determined polyphenols) was lower after 4 months storage and ranged from 3.33 mg/100 g freeze dried sample (raw cv. Birgit/1st day) to 7.27 mg/100 g (raw cv. Lady Claire/8th day). MPP's phenolic content in raw potatoes increased over the storage time, except in cv. Lady Claire potatoes stored for 1 month. Influence of thermal treatments on the MPP phenolic content showed decrease in boiled and fried MPP prepared from 1 month stored potato, while in MPP samples prepared from 4 months stored potato did not follow a clear trend. Phenolic content was lower in boiled potatoes compared to fried potatoes, regardless cultivar type, probably because phenolics are lost by cooking in water. The current study demonstrates that cv. Birgit is more suitable in minimal processing than cv. Lady Claire according to lower phenolic content.
Glucose, fructose and sucrose in minimally processed potato: Effect of cultivar, tuber storage time and heat treatment
- Zdenka Pelaić, Draženka Dite Hunjek, Sandra Pedisić, Maja Repajić, Dino Jakupec, Branka Levaj
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- Journal:
- Proceedings of the Nutrition Society / Volume 79 / Issue OCE2 / 2020
- Published online by Cambridge University Press:
- 10 June 2020, E523
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- Article
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- You have access Access
- Export citation
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Recently, popularity of minimally processed potatoes (MPP) is growing as well as other minimally processed fruits and vegetables, due to its convenience and easy preparation, what consumers nowadays prefer. However, these types of products are very perishable, influenced by a number of factors, particularly cultivar and tuber condition. Potato is suitable for a long storage, but certain changes occur in its chemical composition during storage. These changes, among other factors, greatly depend upon cultivar, as well as storage conditions, and consequently affect on MPP durability and quality. Besides, MPP is subjected to heat treatment before consumption, where raw potatoes chemical composition and the way of heat treatment affect the chemical composition of the prepared potato dish. Potato sweetening is known phenomenon that occurs during storage, what negatively affect on health safety of fried potato.
Therefore, the aim of this study was to investigate the influence of cultivar and tubers storage time, as well as MPP storage time and heat treatment on the sugar content in raw, boiled and fried potatoes.
Potato cultivars Birgit and Lady Claire used in this study were stored for 1 and 4 months in warehouse (8 °C /RH 95 %). MPP was produced by washing, peeling, slicing followed by anti-browning treatment (dipping in 2 % sodium ascorbate solution/3 min), draining and vacuum packing in PE/PA bags. After 1st, 5th and 8th day of storage at 10 °C, MPP were boiled and fried. All samples, including raw MPP, were freeze dried and sugar content was determined by UPLC MS/MS.
Most abundant sugar was sucrose, followed by glucose and fructose, where cv. Birgit contained slightly higher values of all sugars compared to cv. Lady Claire. Initial sugar content of both cultivars was very low. However, during tuber aging, as well as during MPP storage time, content of individual sugars increased in most of samples, with slightly higher increase in cv. Birgit raw samples. Furthermore, heat treatment affects on sugar composition, since glucose and fructose are generally reduced in boiled and fried potatoes with certain differences depending on the cultivar. Total sugar content of cv. Birgit MPP mostly increased during storage, regardless tuber age and the way of heat treatment, while in cv. Lady Claire samples opposite trend with few exceptions was observed. Generally, cv. Lady Claire has lower and slightly more stable sugar content upon tuber aging, MPP storage time and heat treatment.