Preparation of gluten-free crab nugget ( Ucidescordatus ) with added fiber

: Crab meat is rich in nutrients such as polyunsaturated fatty acids, minerals, and vitamins. Its catch is one of the most impor- tant fishing modalities in the North Brazilian state of Pará; however,crab is under utilized in the food industry and mainly sold as fresh meat. The study aimed to develop three formulations of gluten-free crab nuggets with added fiber. To reduce the cost of the final product, three formulations(F1, F2, and F3) were developed by the addition of rice flour at 0% (F1), 15% (F2), and 30% (F3) as a partial replacement of crab meat. Physicochemical and microbiological analyses were performed according to the legislation. In sensory intent analysis, F1 and F2 stood out in relation to F3, butall formulations were well accepted. The cost per unit of the formulations was 0.37 Brazilian reals (R$) for F1, R$ 0.27 for F2, and R$ 0.24 for F3; the formulations obtained a 90.47% yield. For fibers, the same result (0.96 g-dry basis) was obtained for all three formulation s. ácidos poli-insaturados, captura foi desenvolver (nugget) baratear custo F1, F3, arroz e 30%(F3) substituição parcial de caranguejo. Obteve-se para análises físico-químicas e resultados de acordo legislação. sensorial intenção F2 F3, aceitas. das formulações foi 0,37(F1), R$ 0,27(F2) e R$ 0,24(F3); 90,47% rendimento. Para (0,96g- b.s.) nas três formulações. Palavras-chave : nuggets, celíacos, baixo custo. of nugget ( )


INTRODUCTION
Fishing and aquaculture are important sources of employment, especially in developing countries (FAO, 2016). In Brazil, the Northern State of Pará was the largest producer of fish and seafood from aquaculture in 2011, with a total of 142,900 tons, but its aquaculture production is still below its potential. However, territorial extension, water availability, agricultural vocation, logistics favorable to export by sea, and high per capita consumption of fish as well as the state of over exploitation of the main fish stocks make this state a powerful candidate for Brazilian fish farming (BRAZIL, 2013a;IBGE, 2015;BRABO, 2014).
One of the most socially important fishing modalities in the state of Pará is the capture of the uçá crab (Ucidescordatus), which employs a large number of workers . The greatest problems in fishing today are related to the devaluation of fishery resources, such as the under utilization of fishery products and the lack of diversification of fish-processing industry. According to BANDEIRA & NASCIMENTO (2017), fish processing is an alternative to meet the protein needs of the population.
Because fish is a rich source of proteins with high biological value, containing essential amino acids, unsaturated fatty acids, vitamins, and minerals (FAO, 2016) as well as a low cholesterol content, it is a healthier option for consumption than other meats (GONÇALVES, 2011). In addition to being an energy source for the body, the lipids present Silva et al. in fish,i.e., omega-3 fatty acid, docosahexaenoic acid, eicosapentaenoic acid, function as a vehicle for fat-soluble vitamins that have regulatory or coenzyme functions,are precursors in the synthesis of prostaglandins and steroid hormones that play important roles in controlling body homeostasis (RAMÍREZ et al., 2001;BADOLATO et al., 1991), and are important for an optimal neurological development in children as well as for cardiovascular health (FAO, 2016).
However, fish consumption is based on locally available product (FAO, 2014a). Fish byproducts are not usually available in the market, either due to low acceptance by consumers or because health regulations restrict their use (FAO,2016). Processed products derived from the uçá crab could be alternative for the industrialization and popularization of fish because crustacean meat is appreciated in various parts of the world for its texture,unique flavor,and high content of proteins and other nutrients, including essential amino acids recommended by the FAO (1973), particularly lysine, that is present in small amountsin cereals, which is frequently consumed by humans. Furthermore, crab meat is a source of polyunsaturated fatty acids and physiologically important minerals, such as magnesium, manganese, zinc, and copper as well as water-soluble vitamins of the B complex and fat-soluble vitamins (A and D) (OGAWA & MAIA, 1999).
The elaboration of breaded nuggets from crab meat can contribute to an increase in the consumption of this protein source because of its practicality at the time of preparation and the sensory variety of nuggets (BONACINA & QUEIROZ, 2007).
In addition, another component has become an essential part in the formulation of food products, i.e., soluble fibers, because they provide functional benefits and marked positive health effects, such as the prevention or treatment of chronic non-communicable diseases and their manifestations like obesity, hypertension, cancer, blood glucose and cholesterol levels, constipation, cardiovascular diseases, metabolic syndrome, etc. It is a functional ingredient that can be easily incorporated into meat products because of its rheological peculiarities, thus producing enriched foods without impairing the sensory attributes and product acceptability (MENESES & GIUNTINI, 2013;FRUET et al., 2014;GAVANSKI et al., 2015;MARTINO et al., 2016;SOUSA et al., 2019).
To cover gluten-intolerant consumers, the industry of breaded products seeks to completely replace wheat flour with gluten-free ingredients, of which one of the most suitable is rice flour, because it is a versatile product with hypo allergenic properties, low sodium levels, mild flavor, and easily digestible carbohydrates (SIVARAMAKRISHNAN; SENGE; CHATTOPADHYAY, 2004).
The study arises from a perception of the unavailability of industrialized crab-derived food products, aiming to seek the elaboration of a nutritious, practical, functional, and financially accessible food alternative from the elaboration of gluten-free crab nuggets with added fibers, while also adding value to regional raw materials and providing safe food for gluten-intolerant consumers.

MATERIALS AND METHODS
For the preparation of the nuggets, frozen crab meat and other ingredients were selected at the municipal market of the town of Castanhal, State of Pará, Brazil. The preparation and analysis were performed in the food laboratory of the State University of Pará (UEPA).
The fibers were crushed in a household blender until they completely homogenize with the other ingredients of the formulation. The formulation was then molded and stored under refrigeration for 4 hours at −18 °C to achieve abetter consistency. After refrigeration, the nuggets were breaded with predust rice flour, followed by a batter of starch and milk, and a final breading with corn flour. The final products were pre fried in vegetable oil at 180 °C for 1 min. After cooling, some of the nuggets were sent for microbiological analysis and the rest were stored in a domestic freezer at a temperature between −10 °C and −8 °C until the time of microbiological, physicochemical, and sensory analysis, where they were fried in soybean oil at 180 °C for 5 min.

Microbiological analysis
Microbiological analyses were performed for coagulase-positive Staphylococcus according to

Sensory analysis
Tests were performed at the UEPA food laboratory in individual cabins. Nugget consumers were selected among university staff and students. Consumers received an evaluation sheet for each sample. In the acceptance test, the nuggets were evaluated for appearance, aroma, flavor, texture, and overall impression using a hedonic scale of nine points, in which score 1 corresponded to"totally disliked" and score 9 to"liked very much." The samples were randomly coded with three-digit numbers. In addition, we used the intent test with a five-point scale,in which score 1 corresponded to "would never buy it" and score 5 to"definitely would buy it," aiming to evaluate the purchase intention if these nuggets were available in the food market. The samples were separately served in a randomized manner. Thereafter, the preference test was performed, in which the evaluator indicated in descending order his preference, and the samples were simultaneously and randomly served. A total of 73 untrained judges participated in the tests.

Cost and yield analysis
The yield calculations were performed according to ROSALES, BARRIGA & CASTRO (2004) through the relationship between the final product and the initial quantity of raw material using Equation 1. Furthermore, the cost was calculated (Equation 2) based on the price and quantity of raw material used for the preparation of the product (SANTOS, 1999). Equation 1: Yield (%) = (weight of prefried product/weight of breaded product) × 100 Equation 2: Cost (R$) = quantity × price of raw material.

Statistical analysis
The results were analyzed using analysis of variance (ANOVA) at 5% significance level (p<0.05), and a subsequent Tukey's test was performed in Microsoft ® Office Excel software. The results are presented as means and standard deviations for the three nugget formulations.

Physicochemical analysis
The result of the centesimal humidity (Table 1) for F1 (41.8%) did not significantly differ (p<0.05) from F2 (39.2%), but differed from F3 (36.5%). LEITE et al. (2018) reported a moisture content of 7.78% for rice flour, which was much lower than TACO's (2001) for cooked crab, which was 77%. This justifies the direct relationship between the percentage of moisture and partial replacement content of crab with rice flour, in which higher the substitution, lower is the moisture content because of the low humidity present in rice flour; consequently,changing the moisture level of the final product. The moisture content of crab nuggets was lower than the results described by NOLETO et al., (2017) in their study of nuggets with pulp of the shrimp Litopenaeus vannamei and their nutritional content, in which a high percentage of humidity (66.94%) was reported.
F1 with 14.7% lipids did not significantly differ from F2 (12.1%), but differed from F3 (9.9%). The addition of vegetable oil and pre frying, according to FUKUSHIMA et al. (2014), contributes to a 4% increase in fat and a consequent increase in the lipid content of breaded products when compared with the raw breaded product because of oil absorption during the pre-frying process. The difference in lipid content is related to the concentration of crab meat, constituting an important energy source, in addition to polyunsaturated omega-3 fatty acids, which hasa reducing effect on triglyceride and blood cholesterol rates (OGAWA & MAIA, 1999).
The percentages of ash for F1 (3.9%), F2 (3.6%), and F3 (3.2%) did not significant difference, indicating the presence of inorganic matter such as minerals. Crab meat is a source of physiologically important minerals such as zinc, magnesium, manganese, zinc, and copper (OGAWA & MAIA, 1999;PEDROSA & COZOLINO, 2001). The values for ash reported in the nuggets were similar to those reported by EVANGELISTA-BARRETO et al., (2016) who madegluten-free nuggets from Serra Spanish mackerel meat (Scomberomorus brasiliensis) flavored with basil and rosemary and obtained percentages of 3.19% and 3.10%, respectively.
For protein, F1 (30.5%), F2 (29.1%), and F3 (28.6%) did not significantly differ from each other. These values were much higher than those observed by NOLETO et al. (2017) in shrimp nuggets, where a protein content of 15.39% was reported, and by VEIT et al., (2001) who reported 14.67% protein nuggets made from mandi-pintado (Pimelodus britskii) fish meat. EVANGELISTA-BARRETO et al. (2016) reported 22.33% and 19.80% of protein in gluten-free fish nuggets with added basil and rosemary, respectively. Results of crab nuggets were high due to the addition of fiber, such as soybean,which reduces total humidity according to MOREIRA et al. (2016),thus increasing the protein content up to 45%. Additionally, crab meat has a high content of protein (FAO, 1973).
For fiber, the same result (0.96 g dry basis) was obtained for all three formulations because the same type of fiber was added in equal concentrations. They did not qualify as fiber-rich foods because they had a lower content than the minimum requirement recommended by the Brazilian legislation (3 g per 100 g of product) (BRAZIL, 2012). The American Dietetic Association (2002) recommends the intake of 20-35 g of fiber/day for healthy adults; thus, the intake of a portion of the prepared product corresponds to up to 4.8% of the daily amount of fiber recommended for a healthy adult. BERNAUD & RODRIGUES, (2013) reinforced the need for fiber consumption because it is associated with a significant reduction in glucose, blood pressure, and serum lipid levels.
For caloric value, F1 (296.9 kcal) significantly differed from F2 (286.7 kcal), which in turn did not significantly differ from F3 (287 kcal). The values were higher than those found by EVANGELISTA-BARRETO et al. (2016) who reported 216.15 and 205.97 kcal for gluten-free nuggets made from Serra Spanish mackerel meat (Scomberomorus brasiliensis) flavored with basil and rosemary, respectively, probably due to the significant protein content and its influence on energy calculation.

Sensory analysis
Sensory analysis was performed after the study was approved by the Ethics Committee of the Center for Biological and Health Sciences of the State University of Pará (Approval number 2.629.039). In the acceptance test, F1 obtained the highest scores, followed by F2 and F3 varying between scores 7 and 6 corresponding to "liked moderately" and "liked slightly," respectively. From ANOVA for sensory acceptance, there was a significant difference at 5% probability level. As per Tukey's test (Table 2), F1 Table 1 -Results of the centesimal composition of nuggets based on wet weight.
and F2 significantly differed from each other for the color attribute, where as for the other attributes they showed no statistically significant differences. However, both differed from F3. The F3 formulation only equaled F2 in the color attribute, differing in all attributes in relation to F1 (Figure 1). For F1 and F2,the partial replacement of crab mass with rice flour at 15% was not noticeable by the consumer in terms of flavor, aroma, and texture. There fore, this substitution can be done to decrease costs while offering the desired sensory characteristics for the nugget. However, the color attribute showed a significant difference as a result of the addition of rice flour because this gave the product a darker appearance compared with the golden color of the formulation without the addition of rice flour (F1).
In the purchase intent test, only F1 and F2 obtained acceptability indices above 70% with 81.8% and 77.8% rates, respectively. F3 with 58% acceptance indicated a weak market potential. The analysis of the preference test and subsequent Friedman test revealed that F1 and F2 did not significantly differ (P<0.05) in preference, with F3 being the least preferred.

Microbiological analysis
Microbiological parameters were within the limits established by ANVISA in Collegiate Resolution 12 (Table 3), indicating that the nuggets were processed under appropriate conditions; and therefore,were Table 2 -Sensory evaluation of gluten-free crab nuggets with added fibers.

Cost and yield analysis
There is a direct relationship between decrease in the cost of production and replacement of crab meat with rice flour; this is because of the affordable price of rice flour compared with that of crab meat. One nugget unit was found to weigh approximately 9.5 g, with a yield of 90.47% for all formulations, which resulted in a total cost per unit of 0.37 Brazilian reals (R$) for F1, R$0.27 for F2, and R$0.24 for F3 (Table 4).The elaboration of the nuggets resulted in a high-protein crab derivative with a low production cost that can be marketed at an affordable price.

CONCLUSION
All three formulations achieved microbiological quality standards, high protein levels, and compliance with Brazilian legislation in physicochemical parameters. The formulation with 15% added rice flour (F2) stood out for the lower production cost and was the most suitable for production and marketing due to nutritional, sensory, and financial reasons.