Functional, antioxidant, and sensory properties of a ready‐to‐eat wheat flour snack incorporated with germinated legume flour

The present study aimed to develop a protein‐rich product by increasing the nutritional properties of a ready‐to‐eat snack known as “diamond cuts.” Diamond cuts, also known as “papad,” is a crunchy savory snack of South and South‐East Asian countries, typically served between meals in India and Pakistan. In this research three legumes, namely, lentils (Lens culinaris), green gram (Vigna radiata), and black gram (Vigna mungo) were sprouted in a jute bag for 24 h. These were ground to form legume flour and were then used in the preparation of diamond cuts. These products were analyzed for moisture content, percentage expansion, pH, textural characteristics, oil content, peroxide value, total phenolic content, total antioxidant capacity, and sensory characteristics. The results showed that diamond cuts containing germinated lentils, green gram, and black gram containing to have higher total phenolic content (2.29 and 1.25 mg/100 g, respectively) and antioxidant activity (90%, 87%, and 84%, respectively) with improved moisture content. It was also observed that diamond cuts with germinated legumes exhibited significantly harder texture compared to their non‐germinated counterparts. Also, oil uptake was positively correlated to moisture loss is an important parameter in characterizing the physical properties of fried products. In terms of overall acceptability, all germinated fried snacks were liked significantly higher 7.4 than the snacks containing non‐germinated legumes. From the results of sensory evaluation, it is concluded that the incorporation of germinated legumes in diamond cuts would give acceptable color, flavor, and appearance. Therefore, diamond cuts supplemented with germinated legumes could improve the textural, sensory, and nutritional properties of the product.


| INTRODUCTION
Diamond cuts (fried snack), also known as "papad," which is a ribbonlike strip, is a crunchy savory snack of South and South-East Asian countries (Kumar, 2013), typically served between meals in India and Pakistan. The snack is popular among people of all ages notably children and thus may influence overall nutrition (Meng et al., 2010). Also, the demand for diamond cuts is increasing in Asian countries (Kamat & Yenagi, 2012). The recipe of diamond cuts varies from region to region but usually, it is made from selected legumes such as lentil, chickpea, black gram, wheat flour, rice flour, or a combination of these. Legumes belong to the family of Fabacae or Leguminosae. These are good sources of energy, protein, carbohydrate, dietary fiber, minerals (Tharanathan & Mahadevamma, 2003), and other nutrients for population in developing countries. In recent years, legumes have become increasingly popular among consumers and food processors.
This trend is being driven by consumers opting for plant-based protein and eco-friendly food sources (Dhull et al., 2022). As reported by Sumathi et al. (1995), Punia (2000), Negi et al. (2001), and Mubarak (2005), the consumption rate of legumes is limited due to the presence of antinutritional factors, mainly phytic acid, enzyme inhibitors (trypsin and chymotrypsin), oxalates, saponins, tannins, protease inhibitors, lectins, phenolics, and alpha galactosides. These negative factors could be decreased, and the nutritional quality could be improved through the process of germination (Ghavidel & Davoodi, 2011). Germination is the process in which cell constituents are converted into new forms, affecting biochemical properties (Duenas et al., 2009). This process can be differentiated into three phases: In the first phase, imbibition by seed takes place; in the second phase, enzymes get activated, and in the third phase, the radicle is emerged (Ali & Elozeiri, 2017). This process increases enzymatic activity and leads to the conversion of protein, carbohydrates, and lipids into simpler forms (Nout & Ngoddy, 1997), which are more easily digested. Supplementation of germinated legume flour in diamond cuts could be beneficial for human health.
Thus, there is a dire need to develop healthy snacks which could cater to the needs of the market. Therefore, the aim of this research was to incorporate three germinated and non-germinated legume flours, namely, lentils (Lens culinaris), green gram (Vigna radiata), and black gram (Vigna mungo) into the formula of diamond cuts followed by evaluation of its total antioxidant capacity, total phenolic content, oil content, textural characteristics, and sensory characteristics. Moreover, peroxide value was also determined to study the rancidity of the product which is the predator of the shelf life of the snack.

| Raw material
Lentils, green gram, and black gram were obtained from PARC (Pakistan Agriculture Research Council), Karachi, Pakistan.

| Germination
A hundred grams of legume seeds were soaked in distilled water for 12 h. After soaking seeds were then spread on a clean jute bag for 24 h to germinate. The seeds were rinsed after 6 h to reduce fungal contamination followed by drying at 40 C for 3 days. Dried beans were ground to a fine powder (particle size 0.5 mm) using a hammer mill (Sattar et al., 2015).

| Preparation of diamond cuts
Diamond cuts were prepared by mixing all-purpose wheat flour (130 g), salt (3 g), oil (12 g), and germinated/non-germinated legume flour (6 g) and distilled water (100 g) to form a dough. Dough was spread on a plate using a roller pin to a thickness of 5 mm. It was then cut into diamond shapes with a knife. Snacks were then deep fried at a temperature of 170 ± 1 C for 5 min till the development of light golden color. Diamond cuts made completely from allpurpose wheat flour without adding any legume was considered as control.

| Moisture content
Moisture content was determined using AOAC (2019) method.

| Weight gain, percentage expansion, and oil content
Percent weight gain of diamond cuts made from non-germinated and germinated legume flour was recorded. It was evaluated by taking the weight of 10 snacks of each sample before and after frying. The percentage expansion of diamond cuts was calculated using the procedure of Yamsaengsung et al. (2011). The percent expansion was calculated using the following formula: Expansion % ð Þ¼ Length of fried local snack À Length of raw local snack Length of raw local snack Ã 100: The oil from the snack was extracted using the Soxhlet apparatus.
The oil was extracted for 16 h using pet ether as the solvent at a 60-80 C fraction (AOAC & Horwitz, 1975).

| Textural properties
The texture of the diamond cuts was determined by a penetration test to determine the maximum force at penetration, which is defined as "hardness." The equipment used was the Universal Texture Machine (Zwick/Roell,GmbH and Co,. The test was conducted using a 1-mm-diameter cylindrical pointed probe employing 1 KN (Steffe, 1996).

| Preparation of diamond cut's extract
Crushed snacks (10 g) were suspended in 20 ml ethanol (99.5%, v/v) and mixed to form a fine smooth slurry. This ethanolic solution was centrifuged at 3000g for 10 min. Snack extract was obtained from the supernatant and was used to analyze total phenol content and antioxidant capacity (Ashoush & Gadallah, 2011).

| Total phenolic content
The extracted sample (20 μl) was diluted with water (1,580 μl) followed by the addition of 100 μl of Folin-Ciocalteau (FC) reagent. The sample was mixed thoroughly followed by incubation for 8 min. Sodium carbonate solution (300 μl) was added to the extract and the solution was then incubated for 2 h at a room temperature of 28 C. The sample absorbance was measured at 765 nm using UV-visible spectrophotometer (JASCO model V670, JASCO Corporation, Tokyo, Japan). Quantification was performed with respect to the standard curve of gallic acid. The results were expressed as milligrams of gallic acid equivalent per gram of legumes (Waterhouse, 2002).

| Antioxidant activity
The 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) assay was used to determine free radical scavenging activity according to the method of Marinova and Batchvarov (2011). The ethanolic diluted sample (1.5 ml) was placed in a test tube followed by the addition of DPPH solution (0.5 ml) and was stored in dark for 30 min. Absorbance was determined at 517 nm using UV-visible spectrophotometer JASCO, Model V670 (JASCO Corporation, Tokyo, Japan), against diluted blank. The results were calculated from calibration curves, prepared with ascorbic acid (AEAC [ascorbic acid equivalent antioxidant capacity]).

| Peroxide value (PV)
The diamond cuts were analyzed for peroxide value using the formula mentioned below (AOAC, 1984).
where S = mL of sodium thiosulphate (blank corrected) and N = normality of standardized sodium thiosulphate solution.

| Sensory analysis
The tests were conducted in a sensory laboratory. A laboratory with necessary facilities, namely, separate booths, provisions for adequate diffused light, and an air-conditioned odor-free environment, was employed for product evaluation. Sensory evaluation of diamond cuts was performed by 11 trained panelists using a nine-point hedonic scale (1 = extremely dislike and 9 = extremely like). The sensory assessment was made in terms of color, appearance, texture, flavor, and overall acceptability (Juyun Lim et al., 2009).

| Statistical analysis
Analyses were performed in triplicate. The data were analyzed by (analysis of variance) ANOVA using SPSS (Version 17.0. Inc, Chicago, USA) statistical program. Duncan's multiple range tests were carried out to test any significant differences among the treatments employed. Significant levels were defined at p ≤ 0.05.

| RESULTS AND DISCUSSION
3.1 | Weight gain, percent expansion, and oil content Table 1 shows that the highest percent weight gain was observed in control diamond cuts, that is, 97%, which is significantly different from the other samples. Diamond cuts incorporating non-germinated legumes showed significantly higher oil absorption capacity than their germinated counterparts. According to Fan et al. (2005), during frying, heat and moisture transfers are coupled as in the drying process. It is a simultaneous heat and moisture transfer process where moisture leaves the food in the form of vapor, whereas oil is absorbed simultaneously shown in Table 1. Oil absorption is a surface phenomenon in which the frying oil remained on the porous surface region of the fried sample, particularly in the first cell layer. During frying, water is removed from the sample leaving behind void spaces due to the breakdown of adhesive forces between the cells. The oil gets absorbed into these voids' spaces leading to weight gain (Ufheil & Escher, 1996). According to Chavan et al. (2015), food products with higher weight gain after frying could create problems for the product during storage as it would decrease the shelf life owing to oxidative rancidity. The control snack made only from wheat flour showed the highest percent gain of 97% mainly due to oil absorption. However, with the addition of legume flour, the weight gain drastically decreased, which could be due to the water retention capacity of legume flour thus resulting in a lower number of void spaces and decreased oil absorption. More, the water removed from the food matrix, the higher would be the oil absorption (Ziaiifar et al., 2008).
Also, the presence of fibers in legumes results in higher water absorption/retention capacity of the flour matrix. Our observation justified that incorporation of germinated legumes could be used to prepare diamond cuts with better shelf stability and improved nutritional property.
The percent expansion of diamond cuts was determined by measuring the increase in the percentage of length before and after frying as shown in Table 2. Starch expansion depends on the structure and combination of amylose, amylopectin, and sudden change during frying. According to Da Silva et al. (2008), germination increased the embryonic axis by isodiametric cell expansion in which cells are found to be elongated compared to their non-germinated counterparts. This study was parallel to our observation where germinated legumecontaining diamond cuts showed higher percent expansion than control and one containing non-germinated legumes. The percent expansion was also due to the vaporization of water, development of air pores, and uptake of oil (Math et al., 2004). Fried snacks with high expansion during frying are observed to have a crispier texture (Chavan et al., 2015).
The oil content of different samples of diamond cuts is presented in  (Ufheil & Escher, 1996), through which hot oil during frying enters the food. Therefore, incorporating germinated legumes in snacks could be far better than the other snacks. Because the oil content of snacks should be as low as possible from both economic and health points of view (Math et al., 2004).

| Moisture loss
As shown in Table 1, diamond cuts incorporating non-germinated legumes observed significantly (p > 0.05) higher moisture loss than germinated legume-containing diamond cuts, whereas the maximum loss was observed in control diamond cuts. Moisture loss is due to the mass transfer operation in which the moisture of the food samples leaves the food capillaries due to the higher temperature of the frying oil, leaving void spaces that are then occupied by capillary forces (Math et al., 2004). Germination involves a lot of enzymatic reactions, which may hydrolyze carbohydrates providing energy. These hydrolyzed compounds have a higher hydrophilic capacity and therefore prevent moisture loss.

| Peroxide value
Peroxide value determines the content of hydroperoxides in any product. It is also used as an indicator of lipid oxidation (Tiwari et al., 2011). Lipid oxidation is the major cause of food deterioration, which could cause a loss of nutritional quality of the product. tively. The reason could be due to the high stability of total phenols in germinated black gram that prevented oil oxidation. However, the maximum PV was observed in control diamond cuts that contains a low amount of total phenol as shown in Table 1. Also, it could be observed in Table 3 that snacks containing germinated legumes with higher phenolic content showed reduced PV values. Phenols are considered antioxidants being hydrogen donors. Therefore, phenols act as reducing agents and prevent the formation of peroxides in the product and thereby can prolong the shelf life of a product and may play partially the role of synthetic antioxidants.

| Total phenols and antioxidants
Antioxidative activity analysis and the total phenolic content of the snack are presented in Table 3. The results showed that the total phenolic content (TPC) of diamond cuts with germinated legumes increased with percent antioxidant capacity, which could prolong the shelf life of the product. Phenolic compounds may help to prevent cancer and protect against oxidation (Singh et al., 2007). The results showed that the maximum content of phenolic compound was observed in snacks containing germinated green gram, whereas the least was found in the control snack. Snacks containing germinated and their respective non-germinated legumes were compared with the control snack. Thus, the result suggested that significant decreases were observed in the control snack, which were insignificantly different from those in non-germinated legume-containing snacks. Antioxidant activity prevents lipid oxidation by limiting carbonyl accumulation in a product (Jin et al., 2013). The antioxidant capacity of a snack containing germinated lentils showed the highest value of (90%), and the least was observed in control snack content (65%). When comparing the germinated and non-germinated snacks with the control snack, a significant increase in antioxidant activity was observed in the snacks with germinated legumes.

| Texture
The results of measurements of texture are expressed in terms of F max (maximum force necessary to break) the snack is shown in Table 2. It was observed that diamond cuts with germinated legumes exhibited significantly harder texture compared to their non-germinated counterparts due to the difference in the composition of snacks. Yahya (2004) observed that the harder texture of the product could be due to the low-fat content and high protein content. As germinated legumes contain low fat and high protein content (Sattar et al., 2015), therefore, it resulted in an acceptable firmer texture of legumecontaining diamond cuts (Table 2). However, the effect of germinated legumes on the firmness of diamond cuts was more pronounced than the non-germinated legume-containing diamond cuts. The germination process accompanied by the activity of hydrolytic enzymes resulted in the hydrolysis of macronutrients into simple form thus also increasing the level of crude fiber (Sattar et al., 2017). The higher the fiber content, the greater the firmness. Thus, snacks with germinated lentils, green gram, and black gram observed at 1,232, 953, and 1,054 N, respectively, feel crispier than their non-germinated counterparts' samples.

| Sensory analysis
Results from the sensory evaluation of color, appearance, flavor, and overall acceptability of diamond cuts are shown in Table 4. These are the parameters used in judging the property of diamond cuts that reflects the suitability and attraction of the product. Changes in the color of diamond cuts occur because of caramelization, dextrinization of starch, and millard reaction (non-enzymatic browning) in which amino acids react with reducing sugar during baking (Meghaydah et al., 2013). Color and appearance parameters showed high scores in the control snack and germinated lentil-, geminated green gram-, and germinated black gram-containing snacks. Flavor is the main factor that determines the acceptability of a product by consumers, which has the most impact on measuring the success of the product on the market. Observation revealed that the score of the control snack and the snack containing germinated green gram showed 7.1 and 7.3, respectively, which were insignificantly different from other treated snacks except the snack containing non-germinated black gram, as it gave a slightly unpleasant flavor. Overall acceptability is the total reflection of all sensory traits as it determines the appropriateness of the product by the consumer and is mainly based on the hardness, mouthfeel, and taste of diamond cuts. As shown in germinated lentils scored the highest, that is, 7.4, whereas the least score was observed in the snack containing non-germinated lentils.
From the results of sensory evaluation, it is concluded that the incorporation of germinated legumes in diamond cuts would give acceptable color, flavor, and appearance.

| CONCLUSION
The results of the finding revealed that diamond cuts made from germinated legumes influenced the bioactive components. Germinated snacks were also increased in nutritional value, which could be beneficial, especially for the malnutritional and poor group of people in society who cannot afford to consume expensive diets. It has low, minimal processing cost and better overall acceptability besides having high polyphenolic content. This study describes a novel way of incorporating germinated legumes into diet.