Carbohydrate Enzymes Related to Cold-induced Sweetening and Tuber Storage in Potato Genotypes
This study examines how potato cultivars respond to cold storage and the resulting sweetening, focusing on key enzymes such as sucrose synthase and starch phosphorylase. It examines biochemical changes and antioxidant activity over time at low temperatures and identifies genetic factors influencing resistance to sweetening and tuber quality. This comprehensive analysis provides detailed insights into maintaining potato quality during extended storage.
by Jorge Luis Alonso with ChatGPT-4o
Storing potatoes in the refrigerator can make them taste sweeter, which has significant implications for those who enjoy making crispy French fries or chips. This phenomenon, known as cold-induced sweetening (CIS), occurs due to specific changes in the potato’s carbohydrate enzymes. To better understand this, researchers analyzed different potato varieties and their responses to cold storage.
The study focused on three potato varieties: ‘Lady Rosetta’, ‘Kufri FryoM’ and ‘MS/8 1148’. Each variety has different characteristics in terms of resistance to CIS and storage ability. Lady Rosetta’ is known for its resistance to CIS and is good for long-term storage, making it ideal for processing into chips and fries. Kufri FryoM’ is also resistant to CIS but has standard storage capabilities. MS/8 1148' is susceptible to CIS and has a normal shelf life.
Cold-induced sweetening occurs when potatoes are stored at low temperatures (around 4°C). During this time, enzymes in the potatoes break down starch into simpler sugars such as glucose and fructose. These sugars are responsible for the sweet taste. While this may sound appealing, it is undesirable when making French fries or chips. When these sugary potatoes are fried, they tend to brown too quickly and unevenly, often resulting in an off-flavor and darker color. In addition, this process can produce acrylamide, a potentially harmful compound.
The research found that certain enzymes play a critical role in this sweetening process. For example, enzymes such as sucrose synthase (which breaks down sucrose), starch phosphorylase and UDP-glucose pyrophosphorylase were associated with higher levels of CIS in ‘MS/8 1148’ potatoes. This means that starch is more readily converted into sugars in this variety, making it unsuitable for the production of high-quality French fries or crisps after cold storage.
In contrast, ‘Lady Rosetta’ and ‘Kufri FryoM’ managed their enzyme activities differently. Lady Rosetta’ maintained higher levels of starch and resisted breakdown into sugars, thanks to enzymes such as sucrose phosphate synthase, which plays an important role in CIS resistance. This enzyme helps keep simple sugar levels low by redirecting metabolism toward starch synthesis rather than breakdown. As a result, potatoes from this variety remain less sweet and more suitable for frying even after refrigeration.
From a practical point of view, this study highlights the importance of choosing the right potato variety depending on the intended use. For those looking to make crispy, evenly colored French fries or chips, varieties such as ‘Lady Rosetta’ are preferable because they manage their carbohydrate metabolism better under cold storage conditions. This ensures that the potatoes retain more starch and less simple sugars, preventing excessive browning and maintaining better flavor and texture when fried.
On the other hand, for varieties that do not handle this process well, such as ‘MS/8 1148’, the practical recommendation would be to avoid cold storage if the end goal is to make fried potato products. Alternatively, these potatoes could be used for other culinary purposes where the sweetening effect is less of an issue.
In addition, understanding these enzyme activities can also guide agricultural practices and storage solutions. For example, breeding programs can focus on enhancing the activities of enzymes such as sucrose phosphate synthase to develop new potato varieties that are more resistant to CIS. In addition, storage practices can be adjusted to ensure that potatoes are kept at temperatures that minimize unwanted enzymatic activity, thereby maintaining their quality for processing.
In conclusion, the sweet taste that some potatoes develop after refrigerated storage is the result of specific enzymatic activities that break down starch into sugars. This research provides valuable insights into which potato varieties are best suited for refrigerated storage if the goal is to produce high-quality French fries or crisps. By choosing the right varieties and managing storage conditions, it is possible to minimize cold-induced sweetening and ensure that the potatoes remain suitable for frying, providing better taste, texture and safety for consumers.
Source: Aggarwal, N., Dhillon, P. K., Zhawar, V. K., & Sharma, S. P. (2024). Carbohydrate enzymes related to cold-induced sweetening and tuber storage in potato genotypes. International Journal of Vegetable Science, 1–24. https://doi.org/10.1080/19315260.2024.2357800
