Nutritional evaluation of Syagrus coronata kernels and development of cookies prepared with cassava flour and licuri kernels

rosemar.antoniassi@embrapa.br Abstract Syagrus coronata known as licuri, ouricuri, or uricuri is a palm tree from dried areas in Brazil and it is an important resource for the local population. The objective of this work was to evaluate the nutritional value of licuri kernels from the Territory of Sisal (State of Bahia) and to develop cookies prepared with licuri kernels and cassava flour. The licuri kernel showed high content of total dietary fiber (13 -15%) with values equivalent to that observed for coconut kernel. The content of minerals such as zinc, magnesium, phosphorus, manganese, iron, and copper was similar to those recorded for commercial nuts and superior to coconut kernel. The licuri kernel presented an oil content of 61-66%, with a predominance of lauric acid. The main sterols were Sitosterol, Campesterol and Δ5-avenasterol. The formulations of cookies with licuri kernel (5 and 10%) and commercial cassava flour (4.5 and 9%) showed no differences in general acceptance, aroma, flavor, and texture. The kernel of Syagrus coronata represents an important source of dietary fiber, lipids, and minerals and the results indicate that besides its traditional application, this use represents the increasing the nutritional value of cookies in compliance with global


Introduction
Syagrus coronata (Mart) Becc is a palm of Arecaceae family, native and endemic to the Brazilian territory and it can be found in the Northeast (Pernambuco, Alagoas, Sergipe, Bahia State) and Southeast (Minas Gerais State) regions of Brazil (Soares, 2020). This palm grows in the arid conditions of the Brazilian "Caatinga" region with limited water availability and it provides the raw material for the manufacture of a wide range of products in the regions where agriculture is restricted (Santos Moura et al., 2016).
This palm presents medium size, from 8 to 12 meters high and the diameter of the stipe between 20 and 40 centimeters (Gomes et al., 2018). Crepaldi et al. (2001) reported a bunch with 1347 fruits with average length and diameter of 2 and 1.4 cm, respectively. The fruits are ovoid to ellipsoid drupes with fibrous epicarp, yellow to orange pulp, woody endocarp, and endosperm that changes from liquid to solid as the kernel mature (Gomes et al., 2018;Santos Moura et al., 2016).
Syagrus coronata palm is called as licuri and its parts are currently used by the traditional population for construction, handicrafts, as food, to feed domestic animals and wild animals (ex. Lear's Macaw), and as fuel. The fruits are edible and the kernel is used to produce an extract (called as "milk"), to produce candies and for oil extraction (Crepaldi et al., 2004;Lima-Rufino et al., 2008;Andrade Martins et al., 2015). The medicinal applications have been evaluated and the aqueous extract of fruit peels presented antileishmanial activity (Rodrigues et al., 2011). Licuri oil was also evaluated in the diets of cows and goats by Lima et al. (2011) and Silva et al. (2010).
The survey carried out by Folegatti (2012) with families of the cities of Boa Fé, Santa Luz and Valente (Bahia State) evaluated the consumption and daily intake of nutrients of the families. In the Sisal Territory, Semi-Arid region of Bahia State, the conditions for the production of foodstuffs are extremely unfavorable and among the cultivated crops, cassava (Manihot esculenta) is regularly used for many families as toasted flour. On the other hand, some native plants, such as licuri (Syagrus coronata) are also used for human consumption and around 37% of families use of licuri kernel to prepare candies and a milky extract.

Nutritional evaluation of Syagrus coronata kernels and development of cookies prepared with cassava flour and licuri kernels
Although, the protein (1-3%), lipid (0.1-0.3% dry matter), minerals and vitamin contents are very low, cassava is the major carbohydrate source for around 500 million people in the world mainly in the developing countries (Montagnac et al., 2009). This work was designed to assess the nutritional value of the fruit of the licuri collected in the Sisal Territory and the development of cookie formulations, using regional and underexplored raw materials. The nutritional value of food, including cookies, associated with global trends for a wider diversity of ingredients, is constantly pursued as a development goal. In this study, cassava flour and licuri kernel were used as a base for the formulations, evaluated by sensory analysis to expand the variety of foods for the population.

Material
The palms of Syagrus coronata were selected in the cities of Valente, São Domingos and Santa Luz and one sample of licuri kernels was obtained in the fair of the city of Milagres, located in the Sisal Territory, Bahia State, Brazil. The access (A309BF5) was recorded in the Brazilian National System of Management of Genetic Heritage and Associated Traditional Knowledge (SisGen). The bunches were collected and the kernels were obtained after pulp removal and breaking of the endocarp, followed by drying. The kernels were mixed in order to obtain one sample by each city. The nutritional evaluation of kernels was carried out and the result was reported as average of the four samples. The kernels for the essay of cookies production was obtained by sampling of the samples from the bunches. The analysis of kernels and cookies was performed in duplicate. The cassava flour and the ingredients for the cookies were bought as commercial samples in the local market of the city of Cruz das Almas and presented nutritional labelling (Bahia State).

Proximate composition and mineral content
The proximate analysis of Syagrus coronata kernels and the cookies were performed according to AOAC Official methods (Association of Official Analytical Chemists, 2010). The moisture was carried out by drying in an oven at 105 °C to constant weight (AOAC 925.09), the ash content was measured at 550 °C in a muffle furnace (AOAC 923.03/32.1.05). The protein content was calculated based on nitrogen content determined by Kjeldahl method and the factor of 5.75 reported for vegetable products by Brazilian nutritional labeling regulation was used (Brasil, 2020). The total dietary fiber was determined by the enzymatic-gravimetric method (AOAC 992.16/32.1.18). The oil extraction from kernels was carried out in Soxhlet apparatus (petroleum ether 30-60 °C) for 16 hours. The lipids of cookies were extracted according to acid hydrolysis followed by ethyl ether and petroleum ether extraction (AOAC 922.06/32.1.14F). The carbohydrates and calories were calculated according to Brazilian nutritional labeling regulation (Brasil, 2020).
The mineral content was evaluated for kernels and cookies by microwave-assisted wet digestion (Millestone) (AOAC 999.10) or after ash determination (AOAC 999.11), followed by ICP-OES (Inductively coupled plasma -optical emission spectrometry) analysis according to Freitas et. al. (2015).

Fatty acid and sterol composition
For fatty acid profile analysis of kernel oils, the methyl esters were prepared according to Hartman & Lago (1973) and analyzed by gas chromatography on an Agilent 6890 equipment equipped with a fused silica capillary column covered with a cyanopropylsiloxane film (60 m x 0.32 mm x 0.25 μm) and temperature program as described: initial temperature of 100 °C for three min; from 100 to 150 °C with an increase of 50 °C/min; from 150 to 180 °C with an increase of 1 °C/min; 180 to 200 °C with an increase of 25 °C/min, and at the final temperature of 200 °C for 10 min. The sample (1 μL of a 2% solution) was injected into an injector heated to 250 °C and operated in split mode (1:50). A flame ionization detector was kept at 280 °C. Identification was performed by comparing the retention times to NU-CHEK Prep, Inc. (Elysian, MN) standards and quantification was performed by internal normalization. The iodine and saponification indexes were calculated based on the fatty acid composition.
The fatty acid profile of cookies was performed according to AOAC Official method 996.06 (Association of Official Analytical Chemists, 2010) for lipid extraction. The fatty acid methyl esters preparation and gas chromatography analysis conditions were reported above. The quantification of fatty acid was conducted by using Triundecanoin as internal standard and the content of fatty acid was expressed by weight of the sample (cookies).
The sterol analysis of the oil was carried out after obtaining the unsaponifiable matter and the sterol fraction according to American Oil Chemists' Society (2009). The gas chromatography analysis was performed using an Agilent 6890 fitted with a methyl silicone (25 m x 0.32 mm x 0.17 μm) column, and oven temperatures was set at 260 to 290°C at 3°C/min. The injector and detector were kept at 300 °C. The quantification was performed by internal normalization.

Formulation of cookies
The dried ingredients (wheat and cassava flour) were mixed before the addition of the finely ground Syagrus coronata kernels. The shortening, margarine, glucose syrup and sucrose were mixed and the dried ingredients were added followed by water addition, according to the formulations reported in Table 1. The dough was mixed for 30 minutes and after 20 minutes the cookies were baked at 180 °C. Six formulations were previously evaluated and three were selected to sensory analysis. The cookies production was performed in agreement with the guidelines of Good Manufacturing Practice of Embrapa Cassava and Fruits (Cruz das Almas, Bahia State).

Sensory analysis
The sensory analysis was performed at the same day of the production of the cookies. The consumers (25) evaluated the cookies for overall acceptance, appearance, aroma, taste and texture attributes using a 9-point structured hedonic scale ranging Original Article from 1 (dislike extremely) to 9 (like extremely). The presentation followed a completely balanced design according to MacFie et al. (1989). Volunteers signed a consent form with the purpose of the study and the signature certified that they decide to participate and had read the information. The difference among formulations was evaluated by analysis of variance (ANOVA) and by Tukey test (p<0.05) using Statgraphics software (Manugistics, 1993).

Composition of Syagrus coronata kernels
The proximate composition and minerals content of licuri kernels collected in Bahia State were presented in Table 2. The total dietary fiber (TDF) of licuri was 14.4 g/100 g (wet basis -WB).
No comparison was possible due to the differences in methods of analysis employed for licuri kernels in the literature. However, the results obtained for licuri kernels were in the range of TDF of coconut kernel (9.5 and 17 g/100 g (DW) as reported respectively by the Brazilian Composition Table (Universidade Estadual de Campinas, 2011) and Food Data Central of US Department of Agriculture (United States Department of Agriculture, 2020). It is noteworthy that licuri kernels showed higher results for TDF than cashew, Brazil nut, walnut, almond, and hazelnut varying from 4 to 12 g/100 g (WB) (Universidade Estadual de Campinas, 2011; United States Department of Agriculture, 2020). The average oil content of licuri kernels of 63.4 g/110 g (WB) or 67% (DW) was similar to the results obtained by Crepaldi et al. (2001) and Paula et al. (2015) for licuri samples collected in the Brazilian states of Bahia and Minas Gerais State (63-69% calculated as DW) but higher than the observed for the sample collected in Pernambuco State (34% DW) by Silva et al. (2015). These results were reported for samples with higher moisture contents and the comparison was possible only on as dry basis.
The average protein content (9.3 g/100 -WB or 9.9 g/100 g -DW) was consistent with the large range of 5 to 16 g/100 g (DW) observed for licuri kernel by Crepaldi et al. (2001), Silva et al. (2015) and Paula et al. (2015). Differences in reported results probably are due to differences related to the sites of collection such as soil composition and water availability. The protein content of licuri kernel was higher than the results for coconut kernel (∼6% DW) but lower than the figures observed for cashew, Brazil nut, almond, walnut, and hazelnut (14-21%) (Universidade Estadual de Campinas, 2011; United States Department of Agriculture, 2020).
Regarding the minerals, the average contents of calcium, magnesium, phosphorus, potassium, manganese, zinc, and copper of licuri kernels were higher while sodium and potassium contents were lower than the results for coconut kernel reported by Universidade Estadual de Campinas (2011) and United States Department of Agriculture (2020), calculated as a dry basis. Although some mineral contents were lower than the observed for recognized sources of micronutrients such as almond, walnut, and hazelnut, the iron (4 ± 2.7 mg/100 g), zinc (2.4 ± 0.4 mg/100 g), magnesium (146 ± 13 mg/100 g) and phosphorus contents (315 ± 27 mg/100 g) of licuri kernel were in the range observed for these nuts varying from 3-9.7; 2.5-3.1; 158-270 and 290-480 mg/100 g, respectively (United States Department of Agriculture, 2020). The manganese (2.6 ± 0.7 mg/100 g) and copper (1 ± 0.1 mg/100 g) contents of   (Antoniassi et al., 1998) as well as the fatty acid profile and as far as we know this is the first result of sterols for Syagrus coronata kernel oil.

Composition and sensory evaluation of cookies
The composition of cookies prepared with cassava flour and licuri kernel was presented in Tables 4 and 5. There were slight differences among the cookies formulation related to protein (6.3-6.8 g/100 g), lipids (21.6-24.1 g/100 g), ashes (0.7-0.8 g/100 g) owing to the contribution of wheat flour (around 36-40%), the vegetable fat (shortening and margarine) addition from 15 to 20% and the concentration of licuri kernel (5 and 10%) in the formulations. Cassava flour is a traditional Brazilian product used elsewhere in the country showing low protein and oil contents but TDF was reported as around ∼6% (Universidade Estadual de Campinas, 2011). The total dietary fiber (3.1-3.5 g/100 g) of cookies showed the contribution of licuri kernel and cassava flour because the TDF content of wheat flour is low (∼2.3%) (Universidade Estadual de Campinas, 2011). The carbohydrates content (62.3 to 63.5 g/100 g) was the main nutrient because wheat and cassava flour are sources of starch and besides the fat addition, the total calories varied from 475 to 492 kcal/100 g . licuri were in the range reported by Rodushkin et al. (2008) for almond, hazelnut, walnut, cashew and Brazil nuts, ranging from 1.3-5.8 and 1.1-2.2 mg/100 g, respectively. Selenium was detected only in two samples from 10-200 μg/100 g and the variation may be explained by differences in the soil. This occurrence was also observed by Freitas et al. (2008) in Brazil nut samples showing a range of 3 μg/100 g to 51.2 mg/100 g. Aluminum content varied from not detected to 9.6 mg/100 g and lead was detected only in one sample (0.22 mg/100 g) and the results may be attributed not only to samples but also to residues during manipulation of fruits to remove pulp and endocarp for kernel recovery and its storage. Cobalt and molybdenum were not detected.
The kernels of Syagrus coronata is a valuable source of total dietary fiber, lipids and minerals such as copper, zinc, magnesium, manganese and phosphorus.
Among the commercial lauric oils, around 60% of palm kernel oil is used for the production of fatty acids, fatty alcohols, and methyl esters (Rupilius & Ahmad, 2007) while coconut oil is utilized as cooking oil, nutritional supplement, cosmetics and biofuel (Coconut oil boom, 2016).
The high oil content of licuri kernel, the feasibility of oil extraction by pressing of other lauric oils and their broad spectrum of applications indicated that licuri kernel oil may be a successful product of Brazilian biodiversity and a source of income for the collectors.
Regarding sterol profile of kernel oil of licuri samples (Table 3), the main sterol was beta-sitosterol (62.4%), followed by Campesterol (14%), Delta-5-avenasterol (12,1%), and Stigmasterol (7.2%), in agreement with the ranges observed for commercial lauric oils according to the Codex Alimentarius (Food and Agriculture Organization, 1999). Cholesterol was detected up Table 3. Fatty acid composition (g fatty acid/total fatty acid) and Sterol profile of oil from Syagrus coronata kernels (g sterol/total sterols). The mineral results displayed the high contribution of wheat flour and the iron content observed (2.3-2.5 mg/100 g) was due to the mandatory fortification of wheat flour with this micronutrient in Brazil. The sodium content (146-161 mg/100 g) was related to margarine (salted) addition. The zinc content (1.2 to 1.6 mg/100 g) showed the contribution of licuri kernel since the wheat flour and cassava flour presented Zn contents below 0.8 mg/100 g (Universidade Estadual de Campinas, 2011).
The fatty acid composition of cookies showed the contribution of licuri kernel as a source of C8-C14 fatty acids which were lower at T3 -formulation because of the lower content of this ingredient. The presence of trans isomers of C18:1 and C18:2 fatty acids totaling from 2.4 to 3.4 g/100 g of cookies indicated the presence of partially hydrogenated vegetable oil, probably from the shortening. The Brazilian regulation related to nutritional facts demands the claim of trans fat and saturated fat (Brasil, 2020) and the limit to be adopted by January 2023 will be 2 g of trans fat per 100 g of total fat (Brasil, 2019). The sum of saturated fatty acids (7.3-9.8 g/100 g of cookies) was higher than the sum of monounsaturated (4.2-4.7 g/100 g) and polyunsaturated fatty acids (4.7-5.1 g/100 g of cookies) and displayed the presence of partially hydrogenated soybean oil. The main fatty acids were oleic C18:1 cis-9 (3.9-4.3 g/100 g) and linoleic (4.3-4.7 g/100 g of product).
The scores observed for the three cookie formulations evaluated for overall acceptance and the attributes taste, texture, aroma, and appearance (7-7.6) were in the region of "liked very much" and "like moderately" of the hedonic scale except for the score for the appearance of the formulation T1 (6.4). No difference was observed (p<0.05) for overall acceptance and the attributes evaluated. However, the formulation T2, presenting the higher licuri (10%) and cassava flour contents (9%), showed a trend of the highest overall acceptance, aroma, taste, and texture scores (Figure 1). The appearance score was higher for T3 and a similar score observed for aroma was achieved by T1 and T2 formulations.  Structured hedonic scales -1 (dislike extremely) to 9 (like extremely).

Original Article
The results point out the application of licuri kernel as an ingredient of food products besides the traditional application as candies and aqueous extract for cooking.

Conclusion
Syagrus coronata showed potential as a product of Brazilian biodiversity since the kernels are a valuable source of total dietary fiber, lipids, and minerals such as copper, zinc, magnesium, manganese, and phosphorus. The licuri kernel oil presented a similar profile to other lauric oils in relation to the composition in fatty acids and sterols. In addition, the kernels are feasible as an ingredient in the preparation of cookies, as indicated by consumer acceptance and considering that they are a traditional raw material that can be further leveraged.