Millets are ancient cereal grains belonging to the Poaceae family and are increasingly recognized for their nutritional, functional and agronomic importance. They provide carbohydrates, dietary fibre, proteins, minerals and bioactive compounds such as phenolic acids and flavonoids. Their adaptability to dry and semi-arid conditions and low water requirement further increase their importance for sustainable food production and nutritional security (Chapke, 2018; Jena et al., 2023). Despite their traditional importance, millet consumption has declined with the increasing preference for rice- and wheat-based foods. Development of convenient and acceptable millet-based foods can therefore help promote their utilization in modern diets.
       
Among millets, finger millet (Eleusine coracana) is particularly valued for its nutritional composition. It is naturally gluten-free and provides appreciable amounts of dietary fibre, calcium, iron, magnesium and other nutrients, along with polyphenolic and antioxidant compounds (Kalsi et al., 2023; Chandra et al., 2024). Finger millet has traditionally been used in products such as porridge, dosa, bread, ladoo and mudde. However, its use in diversified and convenient value-added food products remains comparatively limited (Ceasar et al., 2025; Kumar et al., 2024). Characterization of finger millet flour is therefore important because its physicochemical and nutritional properties influence processing behaviour and the quality of products developed from it.
       
The increasing demand for gluten-free foods has encouraged researchers to explore naturally gluten-free cereals and pulses as alternative ingredients for developing nutritious food products. Among these, millets have gained significant attention because they provide dietary fibre, essential minerals, phytochemicals and other bioactive components. Their nutritional composition and functional characteristics make them suitable for developing a variety of value-added food products (Jacob et al., 2024; Siroha and Bangar, 2024). Rice flour is also widely incorporated into gluten-free formulations due to its suitable processing and textural properties. However, combining rice flour with nutrient-rich millet and pulse flours can further enhance the nutritional quality of gluten-free products. Finger millet is recognized as a good source of calcium, dietary fibre and minerals, while Bengal gram flour contributes appreciable amounts of protein, dietary fibre and minerals. Thus, the incorporation of finger millet along with rice and Bengal gram flour offers a promising approach for developing gluten-free snacks with improved nutritional value and desirable functional properties. The potential of millet-based ingredients in the formulation of value-added food products has also been reported in recent studies (Mahajan et al., 2024; Ravi and Rana, 2024).
       
Snack foods are widely consumed because of their convenience and palatability, while increasing consumer awareness has created demand for nutritionally improved alternatives. Finger millet sticks have potential as a value-added gluten-free snack; however, their quality depends on appropriate formulation and standardized processing conditions. Increasing the proportion of finger millet may improve nutritional characteristics but can also influence processing behaviour, texture and sensory acceptability. Hence, optimization of formulation and process conditions is important to achieve a desirable balance between nutritional quality and consumer acceptance.
       
Although the nutritional potential of finger millet and its application in value-added foods have been widely reported, the available evidence is relatively fragmented across different products and processing approaches. Limited systematic information is available on gluten-free finger millet sticks that integrate raw material characterization, process standardization, nutritional composition, sensory acceptability, cost estimation and storage characteristics within a single product-development study. In particular, evaluating these parameters together is important for determining not only the nutritional quality but also the practical feasibility, acceptability and stability of the developed product.
       
The development of gluten-free extruded snacks using alternative plant-based ingredients has gained attention due to their potential nutritional and functional benefits. (Giri et al.) investigated the development of functional gluten-free extruded snacks incorporated with banana blossom powder, highlighting the potential of incorporating nutrient-rich ingredients into gluten-free snack formulations. Finger millet (Eleusine coracana) is a nutritionally important cereal that can be utilized in the development of value-added food products. (Sinha and Sharma, 2017) reported on the nutritional properties and sensory acceptability of finger millet-based cookies. Similarly, research on gluten-free cookies has demonstrated the importance of formulation and sensory evaluation in developing acceptable products for consumers (Tanwar and Dhillon, 2017). The nutritional composition, digestibility and antinutritional factors of millet grains are also important considerations in the development of cereal-based food products (Rana and Dahiya, 2022). Furthermore, (Bansal et al., 2022) evaluated the sensory characteristics, nutritional quality and shelf life of millet-based cookies supplemented with carrot powder and sesame. These studies highlight the potential of nutrient-rich ingredients in developing value-added gluten-free and millet-based products. Therefore, the present study aims to develop and characterize gluten-free finger millet sticks, with particular emphasis on their physicochemical, nutritional, sensory and textural properties.
       
Therefore, the present study was undertaken to evaluate the physico-chemical and nutritional properties of finger millet flour, standardize the process for development of gluten-free finger millet sticks, assess their nutritional composition and evaluate sensory characteristics, cost of production and storage stability. The study was aimed at developing a nutritionally improved and acceptable gluten-free snack product while promoting the value-added utilization of finger millet.

Study design and materials
 
The present study was conducted during the academic year 2025-2026 at the College of Food Technology, Vasantrao Naik Marathwada Krishi Vidyapeeth (VNMKV), Parbhani. The investigation comprised characterization of finger millet, development and process standardization of gluten-free finger millet sticks, followed by evaluation of their nutritional, sensory, textural, storage and microbiological characteristics. Good-quality raw materials, including finger millet, rice, Bengal gram flour, salt, chilli powder, cumin seeds and groundnut oil, were procured from the local market of Parbhani. Analytical-grade chemicals and laboratory glassware required for the study were obtained from the respective laboratories of the College of Food Technology, VNMKV, Parbhani. The major equipment used included a digital weighing balance, mixer grinder, hot-air oven, muffle furnace, Soxhlet apparatus, Kjeldahl assembly, cabinet dryer and Texture Profile Analyzer. Flame photometer, spectrophotometer and atomic absorption spectrophotometer were used for mineral analysis.
       
During preliminary formulation trials, bengal gram flour was incorporated at 10% and this level was retained across all treatments to provide a consistent pulse component while allowing the effect of increasing finger millet flour levels to be evaluated. Maintaining Bengal gram flour at a constant level also helped minimize variation in protein contribution and formulation characteristics among treatments. The final formulation levels were selected based on the observations obtained during preliminary trials and sensory acceptability.
 
Characterization of finger millet and flour
 
Selected physical, physicochemical, functional and nutritional properties of finger millet were determined prior to product development. The physical properties included thousand-kernel weight, bulk density, true density, porosity and angle of repose. All measurements were performed in triplicate. Bulk density was determined from the ratio of sample mass to occupied volume, whereas true density was measured using the liquid displacement method. Porosity was calculated from bulk and true density values. Angle of repose was determined from the height and radius of the grain pile using the standard relationship reported by Varnamkhasti et al., (2008). Similar physical and engineering properties of finger millet, including thousand-kernel weight, bulk density, true density and angle of repose, have been evaluated in recent studies, highlighting their importance in characterizing millet grains and assessing their suitability for further processing (Panwar et al., 2024; Ramya et al., 2024; Bhosle et al., 2024). Bengal gram was incorporated at a constant level of 10% in all formulations to provide a consistent contribution to protein content and support the binding characteristics of the developed product. This level was kept constant across all treatments so that the changes in physicochemical, nutritional, sensory and textural properties could be primarily attributed to the variation in finger millet and rice proportions.
       
The proximate composition of finger millet flour and the developed finger millet sticks was determined for moisture, ash, protein, fat, crude fibre and carbohydrate. Moisture content was determined by the air-oven method according to AOAC Official Method 925.10. Ash content was determined by direct incineration according to AOAC Official Method 923.03. Fat content was determined by Soxhlet extraction using petroleum ether according to AOAC Official Method 920.85. Protein content was determined by the Kjeldahl method according to AOAC Official Method 920.87. Crude fibre was determined by the standard fibre digestion procedure according to AOAC Official Method 920.86. Carbohydrate content was calculated by difference.
 
Formulation and process standardization
 
Preliminary trials were conducted to standardize the formulation of gluten-free finger millet sticks with respect to ingredient proportions and product acceptability. Based on the observations from the preliminary trials and sensory evaluation, four formulations were selected for further study. The formulations differed mainly in the proportion of finger millet flour, while rice flour and Bengal gram flour were incorporated at predetermined levels. The composition of the developed finger millet stick formulations is presented in Table 1. The formulations were prepared by replacing rice flour with increasing proportions of finger millet flour while maintaining Bengal gram flour at 10%.


       
For preparation of the sticks, the selected raw materials were cleaned, pre-treated, roasted and milled. The required quantities of the flours were weighed according to the respective formulations and thoroughly mixed with salt, chilli powder, cumin seeds and other ingredients. Hot water was added and the mixture was cooked at 100°C for 15-20 min to obtain uniform dough. The dough was shaped into sticks using a single-screw or hand-operated extruder. The extruded sticks were dried at 60°C for 3-4 h and subsequently fried in groundnut oil at 140°C for 2-3 min. The fried sticks were cooled to room temperature and subjected to quality and storage evaluation.
 
Nutritional, sensory and textural evaluation
 
The developed finger millet sticks were evaluated for nutritional composition, mineral profile, sensory acceptability and textural characteristics.
       
The proximate composition of the finger millet flour was determined for moisture, ash, protein, fat, crude fibre and carbohydrate using the analytical procedures described in Section 2.2. Mineral composition was also evaluated using standard analytical procedures. Potassium was estimated by flame photometry, phosphorus by spectrophotometry, while iron, zinc, manganese and copper were determined using atomic absorption spectroscopy. Calcium and magnesium were estimated using standard analytical procedures. Similar evaluation of proximate and mineral composition, including calcium, iron, zinc, phosphorus, potassium and manganese, has been reported for different finger millet genotypes (Nakarani et al., 2020).
       
Sensory evaluation of the finger millet sticks was conducted by a semi-trained panel comprising staff and students of the College of Food Technology, VNMKV, Parbhani, having prior experience in sensory analysis. The samples were assessed for appearance and colour, flavour, taste, texture and overall acceptability using a 9-point hedonic scale ranging from 9 (like extremely) to 1 (dislike extremely), as described by Ocheme and Chinma (2008) and Kolwate et al., (2021).
       
Texture Profile Analysis was carried out using a Texture Profile Analyzer equipped with a 25-kg load cell and P35 cylindrical probe. Hardness was recorded as the maximum compression force, while crispness was assessed from the major positive peaks in the force–time curve. The samples were compressed to 20% strain, with pre-test, test and post-test speeds of 1, 1 and 10 mm/s, respectively and a testing force of 0.05 N.
 
Statistical analysis
 
The experiment was arranged according to a completely randomized design (CRD), with the treatments assigned randomly to the experimental units. The observations obtained from the different treatments were subjected to analysis of variance (ANOVA) to determine whether significant differences existed among the treatment means. The results were presented as mean values along with the corresponding measures of variability. Differences between treatment means were considered statistically significant at a probability level of P<0.05. Standard error and critical difference were calculated wherever applicable to facilitate comparison among treatment means. The use of randomized experimental designs and analysis of variance provides an appropriate approach for evaluating treatment effects and determining statistically significant differences in experimental food research (Montgomery, 2019).

Sensory evaluation
 
The sensory evaluation of the finger millet sticks is presented in Table 2. Significant differences were observed among the treatments for appearance and colour, flavour, taste, texture and overall acceptability. Among the formulations, T₂ recorded the highest scores for appearance and colour (8.53±0.35), flavour (8.73±0.31), taste (8.50±0.36) and texture (8.17±0.87), resulting in the highest overall acceptability score of 8.47±0.51. The control showed good sensory acceptance, with an overall acceptability score of 8.10±0.40, while T₁ and T₃ recorded overall acceptability scores of 8.17±0.65 and 8.00±0.40, respectively.


       
The superior sensory performance of T₂ may be associated with the optimum level of finger millet incorporation, which provided a suitable balance between the characteristic colour, flavour and taste of finger millet and the sensory properties contributed by rice and Bengal gram. Finger millet incorporation is known to influence the sensory characteristics of value-added foods and optimization of the incorporation level is therefore important for maintaining consumer acceptability. Sharma and Yamer (2022) reported differences in sensory acceptability among finger millet-based products prepared with different levels of incorporation.
       
The higher overall acceptability of T₂ (8.47±0.51) indicates that moderate incorporation of finger millet provided a better sensory balance than the higher incorporation level used in T₃. Although T₃ contained a greater proportion of finger millet, its lower sensory scores suggest that increasing millet incorporation beyond an optimum level may affect desirable sensory attributes. Similar effects of formulation and millet incorporation level on the sensory and nutritional quality of millet-based food products have been reported by Arora et al., (2023).
 
Physical and engineering properties of raw materials
 
Understanding the physical properties of grains and seeds is essential for various aspects of processing and value addition. These properties include thousand kernel weight, porosity, bulk density, true density and angle of repose. Knowledge of these characteristics is critical for designing equipment for handling, transportation, storage and processing. Size, shape and density play a significant role in separation processes, such as those involving oscillating chafers and gravity tables. Bulk density and porosity are vital for developing aeration and drying systems because they influence the resistance to airflow through stored grain masses. Additionally, the angle of repose is a crucial factor in designing equipment and structures for mass flow and storage. This comprehensive understanding of physical properties ensures efficient and effective grain processing and handling, ultimately contributing to the quality and value of the final product.
       
Table 3 presents a comparative analysis of the physical properties of finger millet, rice grain and bengal gram, considering thousand kernel weight, true density, bulk density, porosity and angle of repose. The observed variations in these parameters indicate differences in the size, structure, density and flow characteristics of the selected raw materials, which may influence their handling, mixing, processing and storage during the preparation of gluten-free finger millet sticks.
       
The physical properties of the selected raw materials, namely finger millet, rice grain and bengal gram, are presented in Table 3. Finger millet recorded a thousand kernel weight of 2.90 ± 0.15 g, with a true density of 774±1.58 kg/m³ and bulk density of 1128±1.10 kg/m³. The porosity was found to be 31.38 ± 0.04%, while the angle of repose was 21.10±0.32°. The lower thousand kernel weight may be attributed to the smaller size of finger millet grains. The observed physical characteristics are comparable with the findings reported by Panwar et al., (2024).


       
Rice grain recorded a thousand kernel weight of 21.50±0.17 g, true density of 765.00±4.00 kg/m³, bulk density of 1375.00±6.56 kg/m³, porosity of 43.40±0.17% and angle of repose of 25.41±0.11°. Bengal gram showed the highest thousand kernel weight (287.89±1.24 g) and bulk density (1415.00 ± 8.52 kg/m³), with a true density of 593.90±3.82 kg/m3, porosity of 56.04±0.75% and angle of repose of 35.00±0.47°. The observed variations may be attributed to differences in grain size, structure and packing characteristics. The higher angle of repose of bengal gram indicates comparatively lower flowability. Similar physicochemical variations in rice and bengal gram have been reported by Xu et al., (2021) and Wani et al., (2019), respectively.
 
Nutritional composition
 
The nutritional composition of the finger millet sticks is presented in Table 4. Moisture content ranged from 6.25±0.05% in T₂ to 6.63±0.08% in the control. The relatively lower moisture content of T₂ may be favourable for the crisp nature of the product, although the relationship between moisture and texture should be interpreted together with the instrumental texture results.


       
The progressive increase in protein and fibre content observed with increasing finger millet incorporation indicates the nutritional contribution of finger millet to the developed sticks. Protein increased from 13.39% in the control to 14.04% in T₃, while fibre increased from 2.73% to 3.38%. This improvement may be attributed to the comparatively higher protein and dietary fibre contribution of finger millet. Similar nutritional benefits of millet incorporation have been reported by Jacob et al., (2024), who highlighted the nutritional importance of millets as sources of dietary fibre, protein, minerals and other bioactive constituents.
       
The increase in protein and fibre content observed with increasing finger millet incorporation indicates the nutritional contribution of finger millet to the developed sticks. Protein increased from 13.39% in the control to 14.04% in T₃, while fibre increased from 2.73% to 3.38%. This trend can be associated with the nutritional composition of finger millet, which contains appreciable amounts of protein, dietary fibre, minerals and other nutritionally important components. Similar nutritional characteristics of finger millet and their variation with processing and modification have been discussed by Yasir et al., (2024).
       
Ash content varied from 2.23±0.04% in T₃ to 2.39±0.03% in T₂, while carbohydrate content ranged from 65.68±0.07% in T₃ to 66.40±0.06% in the control. Overall, increasing finger millet incorporation particularly enhanced the protein and fibre contents of the developed sticks, whereas fat showed a slight decreasing trend. These results indicate that incorporation of finger millet can improve selected nutritional attributes of the gluten-free 3.3.
 
Mineral composition
 
The mineral composition of the developed finger millet sticks is presented in Table 5. A clear and progressive increase in the concentration of all evaluated minerals was observed with increasing incorporation of finger millet. Iron content increased from 0.38 mg/100 g in the control to 3.49 mg/100 g in T₃, while calcium increased markedly from 10.00 to 209.15 mg/100 g. Potassium increased from 76.00 to 359.56 mg/100 g, whereas zinc increased from 0.90 to 2.03 mg/100 g. The enrichment of the developed product with essential minerals with increasing finger millet incorporation is consistent with the recognized nutritional importance of millets as sources of minerals and other nutrients (Jacob et al., 2024).


       
A similar increasing trend was observed for copper, manganese and magnesium. Copper increased from 0.12 mg/100 g in the control to 0.37 mg/100 g in T₃, manganese increased from 1.10 to 3.64 mg/100 g and magnesium increased from 35.00 to 120.00 mg/100 g. Among all treatments, T₃ recorded the highest values for every mineral evaluated, followed by T₂ and T₁ while the control consistently recorded the lowest values. This treatment-wise variation may be attributed mainly to the increasing proportion of finger millet in the formulations, as the nutritional and mineral composition of finger millet contributes to the overall composition of the final product (Yasir et al., 2024).
       
The marked increase in calcium is particularly notable because finger millet is widely recognized for its relatively high calcium content compared with several commonly consumed cereals. Recent literature has highlighted the nutritional significance of finger millet, particularly its contribution of calcium and other essential minerals. The present results therefore demonstrate the contribution of increasing finger millet incorporation to the mineral enrichment of the developed sticks (Jacob et al., 2024; Yasir et al., 2024).
       
The SE and CD values at the 5% level indicate statistically significant treatment effects for the reported mineral parameters. The progressive increase from Control to T₃ was therefore associated with differences among the formulations rather than being only a numerical trend. However, the mineral values should be interpreted as characteristics of the present formulations, since mineral concentration may vary depending on raw-material composition, cultivar, growing conditions and processing conditions (Yasir et al., 2024).
 
Texture analysis
 
The texture profile of the developed finger millet sticks is presented in Table 6. The formulations differed in the proportion of finger millet flour and rice flour, while Bengal gram flour was maintained at a constant level. These changes in flour composition altered the balance between starch, dietary fibre and protein in the dough and consequently affected the structural development and fracture behaviour of the sticks (Kumar et al., 2024; Arepally et al., 2023).


       
The T₂ formulation exhibited 22.000 positive fracture peaks compared with 18.800 peaks in the control, representing a 17.02% increase. A higher number of positive peaks indicates a greater number of fracture events during instrumental deformation and is indicative of a more discontinuous and brittle structure. The increased fracture response of T₂ may be related to the structural effect of finger millet fibre within the starch matrix. During cooking, rice starch undergoes gelatinization and contributes to the formation of a continuous matrix. With increasing finger millet incorporation, the relatively fibre-rich flour introduces structural components that can interrupt the continuity of this gelatinized starch phase. Such disruption may result in a more heterogeneous matrix containing localized weak points at the interfaces between starch-rich and fibre-rich regions. During subsequent drying and frying, these regions can act as preferential sites for crack initiation and propagation, thereby producing a greater number of fracture events during compression (Kumar et al., 2024).
       
The increase in fracture peaks may also be associated with the development of the internal cellular structure during frying. Expansion and moisture removal during frying generate pores and air cells within the product, while the surrounding starch-rich material forms cell walls. Changes in flour composition can influence the extent of expansion and the thickness and strength of these cell walls. A structure containing relatively rigid or thicker cell-wall regions separated by pores may resist deformation initially but then fracture at multiple localized sites when sufficient force is applied. This could explain the simultaneous increase in hardness and positive fracture peaks observed for T₂. Thermal processing of millet-based foods can alter starch structure through gelatinization, moisture evaporation and starch-lipid interactions, thereby influencing the final textural characteristics of the product (Kumar et al., 2024).
       
The hardness of T₂ was 14,096.229 g compared with 11,404.707 g for the control, representing a 23.60% increase. The higher hardness indicates that greater force was required to deform or fracture the T₂ sticks. This increase may result from the combined effects of finger millet dietary fibre, starch behaviour and moisture redistribution during processing. Fibre particles can restrict the mobility and continuity of the starch phase, while cooking, drying and frying progressively reduce moisture and strengthen the resulting solid structure. During frying, moisture loss also promotes the formation of a rigid outer structure, whereas oil penetrates into the developing porous matrix. The extent and distribution of oil within the pores and cell-wall regions can influence the final mechanical response of the product. Therefore, the higher hardness of T₂ is likely to reflect changes in matrix continuity, pore structure, cell-wall characteristics and moisture-oil distribution rather than the effect of finger millet flour alone. Similar effects of flour composition and processing conditions on hardness and other textural properties have been reported in millet-based snack systems (Arepally et al., 2023).
       
The simultaneous increase in hardness and fracture-peak number is particularly important for interpreting the texture of T₂. The sample was harder than the control, but it also produced more fracture events, indicating that the product was not simply harder; rather, it developed a firmer structure capable of undergoing multiple fracture events during deformation. This combination can contribute to the perception of crispness in dry snack products because crispness is associated with repeated structural failure of brittle cell walls.
       
The instrumental texture results were consistent with the sensory evaluation to some extent. T₂ recorded a texture score of 8.30 and the highest overall acceptability score of 8.607, despite showing 23.60% higher hardness than the control. The control had a texture score of 8.27 and an overall acceptability score of 8.365. Thus, the increase in instrumental hardness in T₂ did not negatively influence sensory acceptance. Instead, the higher positive peak count (22.000) together with the higher hardness suggests that the moderate increase in structural firmness was within the acceptable sensory range and may have contributed to a desirable firm and crisp texture. Therefore, instrumental hardness should not be interpreted independently of fracture behaviour when explaining consumer-perceived texture.
       
The lower overall acceptability of T₃ (8.102), despite its higher finger millet incorporation, suggests that increasing finger millet beyond the optimum level may produce structural and sensory changes that are less preferred. However, because instrumental texture values for T₁ and T₃ were not reported in the present Table 5, a direct treatment-wise correlation between hardness, fracture peaks and sensory scores cannot be established. The available results therefore support the conclusion that T₂ provided the most favourable balance between instrumental firmness, fracture behaviour and sensory acceptability among the formulations for which texture measurements were available.
       
Overall, the textural behaviour of the sticks appears to result from an interaction between flour composition and processing-induced structural changes. Finger millet incorporation can modify the continuity of the starch matrix, moisture distribution, pore development, cell-wall characteristics and oil distribution during frying. These structural modifications can collectively increase resistance to deformation while also increasing the number of fracture events, producing the characteristic firm and crisp texture observed in T₂ (Kumar  et al., 2024; Arepally et al., 2023).

The present study demonstrated that incorporation of finger millet flour into gluten-free snack formulations improved selected nutritional attributes while maintaining acceptable sensory and textural characteristics. Among the formulations evaluated, T2 containing 40% finger millet flour showed the highest overall sensory acceptability, with desirable colour, flavour, taste and texture. The selected formulation also exhibited satisfactory crispness and textural characteristics, together with an improved nutritional profile, particularly in terms of dietary fibre and mineral content. These findings indicate that appropriate incorporation of finger millet flour can enhance the nutritional quality of gluten-free snack products without compromising their sensory acceptability. Overall, the developed finger millet sticks represent a promising value-added gluten-free product, with potential for further product development and future scale-up studies.

The authors extend their gratitude to Dr. V.S. Pawar, Research Guide, for continuous guidance and support.
 
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The views presented in this manuscript are those of the author, who is solely responsible for its content and accuracy.

The authors declare that there are no conflicts of interest regarding of the publication of this research paper. No funding or sponsorship influenced  the design study, data collection, analysis, decision to publish, or preparation of the manuscript.