20 Apr Can pre-treatment processes improve the quality of fried banana chips?
Patchimaporn Udomkun, Bhundit Innawong, Emmanuel Njukwe
1 International Institute of Tropical Agriculture, Bujumbura, Burundi
2 Food Technology Department, Faculty of Engineering and Industrial Technology, Silpakorn University, Nakhon Pathom, Thailand
Fast food processing, the palatable taste of fried food, and considerable economic benefit make deep-fat frying one of the most popular cooking methods in the household kitchen, fastfood restaurant, street-food vendors, and industries. The sale of pre-cooked and ready-to-eat products such as chicken nugget, French fries, and potato chips, all of which are prepared by deep-frying process has dramatically increased in the western world and is rapidly expanding throughout the developing countries.
Frying involves submerging food in extremely hot oil (~160-180 °C) until it reaches a safe minimum internal temperature. When the food is deep-fried properly, it is endowed with an attractive flavor, golden-brown pellicle (a skin or membrane on the surface of meat, fish, or poultry, which allow smoke to better adhere to the surface during the smoking process), and crisp texture. While deep-frying can give delicious results, many complex chemical reactions also occur in both the fried material and frying oil. Due to a high uptake of oil in deep-fried food, several studies have shown that consuming this product can be harmful to health as it can lead to coronary heart disease, diabetes, or hypertension. Moreover, a high accumulation of acrylamide – a chemical that can form in some foods during high-temperature cooking processes – in deep-fried food, especially in starchy-rich foods containing asparagine (amino acid) and reducing sugars, can potentially cause degenerative nerve changes via chronic oral intake (Parzefall, 2008), and introduce possible carcinogens to humans, classified in Group 2A by the International Agency for Research on Cancer (IARC) (Hsu et al., 2016).
Vacuum frying technology offers a better alternative in providing healthy and high-quality products to satisfy the expectations of fried food consumers. It is mostly used to preserve qualities of tropical fruits such as pineapple, mango, banana, avocado, and durian, apart from roots and tubers. Vacuum frying is also a deep-fat frying process, which is carried out in a closed system, below the atmospheric pressure, substantially reducing the boiling point of water and, hence, the frying temperature (~60‒70 °C). From the industrial point of view, vacuum frying has shown several advantages, such as lower oil content, lower acrylamide content, better preservation of natural color, flavors, and nutritional compounds, and better energy saving. Many Asian countries such as Indonesia, Thailand, Japan, and Vietnam are using the technology to produce highly nutritious snacks and vacuum-fried fruit can be added as ingredients to a variety of ready-to-eat breakfast cereals.
Apart from the advantage of consumers becoming aware of healthy lifestyles, vacuum frying has certain disadvantages, such as low efficiency especially with low-temperature frying, relatively high oil uptake in products, and quality attributes of fried products need to be improved. To overcome these problems, many processors seek ways to produce lower oil containing products. As a result, there have been strong incentives to introduce several pre-treatment methods that could produce foodstuffs with lower oil contents and with desirable sensory quality characteristics, such as coating with cellulose derivatives and/or modified starches, dipping in osmotic solutions, or partial dehydration by heating process. However, studies on the use of pre-treatment as a partial dehydration process prior to vacuum frying are rather limited. This study was undertaken with Dr. Bhundit Innawong from the Department of Food Technology, Silpakorn University, Thailand, to investigate the effects of osmotic dehydration (sucrose and salt solutions), microwaving, and air-drying before frying on physical and chemical characteristics of vacuum and atmospheric-fried banana chips. The fryer apparatus is presented below (Figure 1).
To answer the question ‘can pre-treatment processes improve the quality of fried banana chips?’, the study confirmed that vacuum frying has been demonstrated as a highly promising processing technology enabling the production of safer crisps with improved quality values when compared to atmospheric frying. It was observed that pre-treatment process is a good technique, which can reduce moisture and oil uptake in both atmospheric and vacuum-fried banana chips. Vacuum-fried banana chips have better qualitative parameters resulting in a better-quality value for the pre-treated fried product with less oil. Due to a lower frying temperature and limited oxygen access, pre-treatment process can also improve the color of banana chips (see Fig. 2). For sensory evaluation, consumers mostly preferred the osmo-dehydrated chips with sugar solution due to a desirable taste and color.
In Udomkun P, Innawong B, 2018. Effect of pre-treatment processes on physicochemical aspects of vacuum fried banana chips. Journal of Food Processing and Preservation 42(8), https://doi.org/10.1111/jfpp.13687.
W.Parzefall. 2008. Mini review on the toxicity of dietary acrylamide. Food and Chemical Toxicology, 46, pp. 1360-1364.
H.-T. Hsu., M.-J. Chen., T.-P., Tseng, L.-H., Cheng., L.-J., Huang, T.-S., Yeh. 2016. Kinetics for the distribution of acrylamide in French fries, fried oil and vapour during frying of potatoes. Food Chemistry, 211, pp. 669-678.