Page 50 - FoodFocusThailand No.222 September 2024

SMART PRODUCTION

Conventional superheated steam drying at atmospheric
pressure still requires high operating temperatures,
making it unsuitable for some raw materials such as
vegetables, fruits, and herbs that degrade easily under
such conditions. To address this limitation, a novel drying
technique has been developed. Combining the benefits
of superheated steam drying with the capability to operate
at lower temperatures, LPSSD leverages the principle
that water boils at a lower temperature if the system
(ก) ขนมขบเคี�ยุวัจำากกล้วัยุหัอมทอง pressure is reduced. This in turn allows for the production
(A) Snack prepared from Gros Michel banana of superheated steam at a lower temperature. Continuous
research and development in LPSSD has led to the
manufacturing of an industrial-scale dryer (Figure 2) that
use this principle, enabling the production of a wide variety
of high-quality dried food products, including fruit snacks
(Figure 3).

Case Study: Commercial Application of
Advanced Drying Technology
Gros Michel banana is one of the raw materials that a
company who has adopted the LPSSD technology uses
to prepare fruit-based snack for sale (Figure 3A). In terms
of texture, the hardness of LPSSD-dried banana is over
(ข) ขนมขบเคี�ยุวัและอาหัารอบแหั้งอ่�น ๆ ไดิ้แก่ มะพร้าวัอบแหั้ง ทุเรียุนอบแหั้ง 100% lower than that of its freeze-dried counterpart; the
crispness of the former is also around 70% than that of
และสัมุนไพรอบแหั้ง
(B) Snacks and other food products viz. dried coconut, dried durian, the latter. Compared to hot air-dried banana of the same
and dried herb thickness, LPSSD-dried banana exhibits 130% lower
hardness and 70% higher crispness. Such improved
ภาพที่่� 3 ตััวัอยุ่างผลิตัภัณฑ์์อบแหั้งโดิยุใชี้ไอนำ�าร้อนยุวัดิยุิ�งที�ควัามดิันตัำ�า texture is due to the higher porosity achieved by LPSSD.
Figure 3 Examples of LPSSD-dried food products Nutritionally, fully yellow banana with a ripeness scale
ที่่�มา: บริษััท เนเชีอรัล โปรดิิวัซ์์เซ์สั จำำากัดิ of 5, which is used by the company to produce the banana
Source: Natural Produces Co., Ltd. snack, possess higher levels of fructooligosaccharides
and inulin, which function as prebiotics, compared to less
returning to its saturation condition. While saturated steam can ripe banana. Thanks to LPSSD, fully ripe banana can be
theoretically be reheated into superheated steam, the amount of used to produce dried banana snack. This distinctive
steam released from the drying chamber is expectedly larger than benefit sets LPSSD apart from other industrial drying
the amount fed to the chamber. The excess steam is indeed technologies, particularly hot air drying, which cannot
equal to the amount of evaporated moisture; this excess steam handle fully ripe banana for highly crispy snack production.
should be eliminated from the system to avoid overburdening LPSSD can be used to produce snacks or other dried
the superheater. The excess steam can be used in other foods such as leafy vegetables, spices, and herbs of
processes or condensed into hot water, which can be utilized higher quality in terms of color, texture, and nutritional
elsewhere. characteristics. Despite higher equipment and operating
An important characteristic of superheated steam drying is costs compared to hot air drying, LPSSD is an attractive
the ability to recycle most of the energy introduced into the drying alternative with much potential for commercial
system or use it in other processes, thereby reducing the overall application.
energy consumption of the drying system. Another distinctive
feature is the minimal availability of oxygen, as the air inside the
drying chamber would almost entirely be replaced with superheated
steam. Such an environment significantly reduces or eliminates More Information Service Info C006
undesirable oxidation reactions, including enzymatic browning
reaction, lipid oxidation, and enzymatic vitamin degradation. เอกสารอ้างอิง / References
Furthermore, superheated steam drying results in a higher-porosity สัักกมน เทพหััสัดิิน ณ อยุุธยุา. (2555) การอบแหั้งอาหัารและวััสัดิุ
ชีีวัภาพ. สัำานักพิมพ์ท้อป กรุงเทพ ฯ [Devahastin, S. (2012).
product compared to hot-air drying, owing to the boiling of moisture Drying of Foods and Biomaterials. Top Publishing, Bangkok
(water) within the food structure during the former drying process. (in Thai)]
As water transforms from liquid to vapor, water expands and Devahastin, S., Suvarnakuta, P., Soponronnarit, S., Mujumdar,
pushes against the food internal structure, increasing its volume A.S. (2004) A comparative study of low-pressure superheated
and porosity. This phenomenon allows superheated steam-dried steam and vacuum drying of a heat-sensitive material. Drying
products to possess lower hardness and higher crispness as Technol. 22, 1845-1867.
Pongmalai, P., Devahastin, S. (2020). Profiles of prebiotic
well as the ability to rapidly rehydrate, all of which are quality fructooligosaccharides, inulin and sugars as well as
traits highly valued by snack producers and other relevant physicochemical properties of banana and its snacks as
industries. affected by ripening stage and applied drying methods.
Drying Technol. 38, 724-734.
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