OPTIMIZATION OF THE PHYSICOCHEMICAL PROPERTIES OF POWDER OBTAINED FROM JERUSALEM ARTICHOKE TUBERS

ABSTRACT

This study investigates the production of functional food powder from Jerusalem artichoke (Helianthus tuberosus L.) using laboratory convective drying. The aim is to obtain a natural, fiber-rich ingredient suitable for functional and dietary food formulations. Fresh tubers were washed, peeled, sliced (3 mm), and dried at 50°C, 55°C, and 65°C. Drying temperature significantly influenced color, moisture reduction, drying duration, and powder yield. The vitamin composition of the dried samples was analyzed using FTIR and UV-Vis spectroscopy. The optimal drying temperature was determined to be 55°C, providing a balance between product quality and energy efficiency.

АННОТАЦИЯ

В данном исследовании рассматривается получение функционального пищевого порошка из топинамбура (Helianthus tuberosus L.) с использованием лабораторной конвективной сушки. Цель работы — разработать натуральный, богатый пищевыми волокнами ингредиент, пригодный для использования в составе функциональных и диетических продуктов. Клубни были очищены, нарезаны на ломтики толщиной 3 мм и высушены при температурах 50°C, 55°C и 65°C. Установлено, что температура сушки существенно влияет на цвет, снижение влажности, продолжительность процесса и выход порошка. Витаминный состав высушенных образцов был проанализирован с использованием FTIR и UV–Vis спектроскопии. Оптимальной температурой признана 55°C, обеспечивающая наилучшее сочетание качества продукта и энергетической эффективности.

Keywords: Jerusalem artichoke, inulin, convective drying, powder technology, functional product.

Ключевые слова: Топинамбур, инулин, конвективная сушка, технология получения порошка, функциональный продукт.

Introduction

The global demand for functional foods has significantly increased over the last decade. Consumers are seeking naturally derived ingredients that support digestive health, immunity, and overall wellness. Jerusalem artichoke (Helianthus tuberosus L.) is recognized as one of the richest natural sources of inulin—a prebiotic polysaccharide with scientifically demonstrated benefits [1].  Inulin promotes healthy gut microbiota, stabilizes blood glucose levels, and enhances mineral absorption, making it an essential ingredient for dietary [2].  

In Uzbekistan, the cultivation of Jerusalem artichoke has expanded, yet processing functional food technologies remain underdeveloped. Producing high-quality powder from this plant requires optimized drying methods that preserve its biochemical components. Convective drying is considered a practical and cost-effective method for small-scale laboratories and industrial applications [3].

The objective of this research is to investigate the influence of different drying temperatures (50°C, 55°C, and 65°C) on the quality and technological properties of Jerusalem artichoke powder and to propose a technological line suitable for further industrial adaptation.

Materials and methods

Raw Materials. Fresh Jerusalem artichoke tubers of the “Mo‘jiza” variety were collected from the Khorezm region. Only clean and undamaged tubers were selected.

Sample Preparation

• Washing under running water

• Manual peeling

• Slicing into 3 mm discs using a laboratory vegetable slicer

Drying was conducted in a laboratory convective dryer (Memmert UN30) at: 50°C, 55°C,  65°C.

Analytical Methods. Moisture content was determined in accordance with GOST 28561–90 by drying samples at 105 ± 2°C until constant mass was achieved [4]. Drying time was measured using a laboratory timer. All measurements were repeated three times, and mean values were calculated with standard deviations. Additionally, changes in color and texture were visually assessed and compared among the samples dried at different temperatures.The experiments were repeated three times, and the results were analyzed based on average values [5]. 

Vitamin C and E contents were analyzed using FTIR and UV‑Vis spectroscopy. FTIR spectra were recorded in the range of 400–4000 cm⁻¹, and key absorption peaks corresponding to vitamin C (O–H stretching, C=O stretching) and vitamin E (CH₂, CH₃, aromatic C–O vibrations) were evaluated. UV‑Vis analysis was carried out using ethanol  extracts at appropriate wavelengths [6].

Results and discussion

Drying Behavior

At 50°C, drying was slow but preserved color well.

At 65°C, drying was fast but caused noticeable browning due to Maillard reactions.

At 55°C, the balance between time and quality was optimal.

Table 1.

The vitamin content of the 3 different samples

Figure 1. IQ-spectrum of the aqueous solution of Jerusalem artichoke samples (for vitamin C)

Figure 2. IQ-spectrum of the hexane solution of Jerusalem artichoke samples (for vitamin E)

Figure 3. IQ-spectrum of the ethanol solution of Jerusalem artichoke samples (for vitamin E)

Vitamin Composition. Analysis of vitamins C, E, and A revealed that drying temperature influenced their stability differently.

Vitamin C. Vitamin C showed a slight decrease at higher temperatures. Samples dried at 55°C retained more vitamin C compared to those dried at 65°C, which aligns with the known heat sensitivity of ascorbic acid.

Vitamin E. Vitamin E demonstrated good thermal stability. FTIR  results showed minimal variation between samples, suggesting that moderate heat did not significantly degrade tocopherols.

Vitamin A. Vitamin A (expressed in µg/ml) was determined using UV-Vis spectroscopy in ethanol extract.  Raw tubers contained the highest vitamin A concentration. Samples dried at 55°C maintained higher vitamin A levels compared to 65°C.

Powder Characteristics. Powders produced at 55°C showed:

•  Color is similar to that of wheat flour

• Smooth texture

• Higher solubility

• Stable aroma

• Minimum heat damage

Table 2.

Drying Parameters for Peeled Jerusalem Artichoke

Table 3.

Drying Parameters for Unpeeled Jerusalem Artichoke

Conclusion

Drying Jerusalem artichoke at 55°C proved to be the most favorable condition, ensuring an optimal balance between drying time, powder yield, color retention, and vitamin preservation. Compared to 50°C and 65°C, the 55°C regime improved powder yield by approximately 1–4% and reduced drying time by about 50 minutes while maintaining higher vitamin stability.

The resulting powder preserved natural aroma, light color, and smooth texture, making it a suitable functional ingredient for dietary and wellness‑oriented food products. The process is simple, energy‑efficient, and feasible for scaling in both laboratory and industrial environments.

References:

1. Gonchar V. V., Vershinina O. L., Roslyakov Yu. F. (2013). Use of Jerusalem artichoke powder in bakery and confectionery technologies. Khleboprodukty, No. 10, p. 46.
2. Dozhdaeva M. I., Gonchar V. V., Kolashnova T. V. (2011). Development of diabetic confectionery products using Jerusalem artichoke derivatives. Food Technology, No. 2–3, pp. 65–67.
3. Siddiqui, S. A., Kumar, M., et al. Impact of drying on techno-functional and nutritional properties of food materials. Drying Technology, 2024.
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