One of the biggest problems found in developing countries is the deficiency in the intake of protein by part of the poor populations, which demands incentive policies to consume vegetable protein with low cost and good quality.

 

As an alternative to the problem, soy was used due to its adequate source of protein, accessibility and low cost; however, variety in feeding habits from the inclusion of different legumes such as peanut may help minimizing that necessity as well as enriching one’s diet (Sim et al., 2012; Pretti, 2010; Bede, 2007).

 

Peanut is a legume of global fame and it is cultivated in all of the national territory. It is widely used in industries and the making of many products due to its nutritional values. It is considered a highly energetic food, as it contains 48.7% of oil and 80% of unsaturated fatty acid, amongst which oleic and linoleic. Oil and its proteins have high nutritional quality which determines the expressive economic value in developing countries. Peanut still presents important amounts of vitamin E, vitamin B1 and folic acid (Granato et al., 2009).

 

Some types of aliment have been thoroughly studied as alternative source in the making of products for human feeding in  the  form of  aqueous  extract.  Therefore, the formulation of mixed ready to drink beverages with vegetable basis may be used to improve the nutritional characteristics of certain products (Jain and Khurdiya, 2004) by the complementation of nutrients provided by different vegetables such as peanut and guava, peanut and umbu.

 

According to Pro-peanut (2010), pro-amendoim and other products derived from peanut such as peanut butter have been prioritized by ONU to be distributed in Haiti, especially amongst children who are more affected by the country shortage, due to its value as energetic food and its rapid action in the human organism as it concentrates three sources of calories (peanut, sugar and oil).

 

In this context, the present paper aimed at producing two beverages based on peanut extract enriched with guava and umbu fruit pulp as well as studying the effect of storing the beverages at the temperature of -18°C (-0.4F) for 150 days thus characterizing them by raw protein, humidity, pH, total titratable acidity and ashes.

Location of the experiment

 

The experiments took place in the Laboratory of Storage and Processing of Agricultural Products of the Academic Unit of Agricultural Engineering at Federal University of Campina Grande and the Department of Research and Extension in Aliment of the Center of Sciences and Technologies at State University of Paraíba, both in Campina Grande, Paraíba, Brazil.

 

Obtention of raw material

 

Peanut grains manufactured by Ioky used in the experiments were obtained from a  supermaket  store  in  Campina  Grande,  Paraíba, Brazil. Umbu (Spondias spp.) as well as guava (Psidium guajava L.) fruit pulp were obtained in frozen state at a factory of fruit pulp. Both fruit pulp were homogenized and repacked in low density polyethylene bags. Part of the samples were characterized as to humidity, dry extract, pH, acidity, ashes and soluble solids as the other part was stored in a freezer at the temperature of -18°C (-0.4F) until they were used in the experiments.

 

Preparing of the extract peanut extract

 

Peanut grain samples were manually peeled, soaked into water at ambient temperature for 8 to 12 h (maceration time) and subjected to water heating until ebullition, point in which remained for 5 min; afterwards the grains were dried and washed in running water. The cooked grains were disintegrated with water at 60°C (140F) in a machine developed for this specific purpose named vaca mecânica [mechanic cow]. Regarding the disintegration of the grains, the grain:water ratio was evaluated (1:8 weight/volume) according to physical-chemical and sensorial analysis. The extract produced was subjected to whitening (at ± 98°C [208.4F] for 5 min) after which it was stored in polyethylene terephthalate (PET) bags at -18°C (-0.4F). In Figure 1, the flowchart of the preparation of the peanut extract is presented.

 

 

Beverage formulation

 

In order to make the peanut based beverages in the enrichment process, guava and umbu fruit pulps without any treatment were used. Three formulations (Table 1) were elaborated aiming at a selection via physical-chemical analysis. The quantity of pulp and the peanut extract were obtained considering the soy based beverage and the fruit pulps. In each analysis, 480 g of each pulp and 200 g of grains was used.

 

 

 

Statistical design

 

The results were analyzed with Programa Computacional Assistat (Silva and Azevedo, 2006) [Assistat Computational Program], version 7.4 beta, using the completely randomized design. The results were tested in beverages stored at the temperature of 18°C (-0.4F) and 3x2x4 (3 formulations, 2 pulps, 4 periods of storage). The means were compared with Tukey’s test at 1 and 5% probability.

 

Centesimal composition of the umbu and guava pulps and the peanut extract

 

The approximate centesimal composition of the pulps (umbu and guava) and the peanut extract is described in Table 1. The values for ashes (0.41%) and humidity (86.54%) found for the guava pulp were very close to the values on the Brazilian Table of Aliment Composition (Taco, 2011) which determines for guava pulp 0.5% ashes and 85% humidity. The acidity values (0.59%) were superior to those found by Brunini et al. (2003) who have obtained at the beginning of the storing of guava pulp 0.40% acidity. Such differences may be related to a variety of causes, such as the location of the orchard, rainfall, light, which influence either directly or indirectly the development of each variety and consequently its components.

 

Data analysis enabled the statement that pH value (4.17) for guava pulp (Table 2) was superior than the ones found by Machado et al. (2007), who evaluated the quality of four brands of frozen guava pulp and obtained mean pH of 3.90, and by Brunini et al. (2003), who  found in the characterization of the guava pH of 3.86. However, the values are acceptable according to the interval from 3.5 to 4.20 established by the Ministry of Agriculture and Provision for beverages with guava.

 

 

In regard to the data exposed in Table 2 for the umbu pulp, the values found in this paper for pH analysis (2.74) are superior to the ones found by Carmo et al. (2012), who obtained 2.75 pH for umbu juice, and Souza et al. (2010) who achieved pH of 2.3. Comparing the quantity of ashes of the umbu pulp in this paper (0.30%), the former is inferior to the value found (0.5%) by Ferreira et al. (2000). Mean values for humidity (92.1%) were superior to the found by Souza et al. (2012) who verified in their study values of 89.70%. The mean value for total titratable acidity of umbu (1.73%) is closer to the one found by Ferreira et al (2000) in their work with frozen umbu pulp (1.30%) during 180 days of storage.

 

As for the data achieved for the peanut extract, the quantity of ashes and protein is similar to the one found by Kouane et al. (2005) who obtained values of 0.2 and 2.80% for both aspects, respectively. Also, with respect to protein content (2.46%) was superior to that obtained by Rubico et al. (1987) that was 2.14%.

 

Centesimal composition of the formulated beverages

 

Ashes

 

In Table 3, the mean values for ashes (%) for the beverages formulated by the peanut extract and umbu and guava pulps are presented. It is noted in each formulation the statistical superiority of the peanut extract and guava beverage compared to peanut extract and umbu beverage: 0.16 (57.14%) in formulation 40P:60PE, 0.17 (73.91%) in formulation 50P:50PE, and 0.18 (78.16%) in formulation 60P:40PE. Such result is probably due to a higher concentration of  minerals  in guava pulp (0.5%) over umbu pulp (0.4%). Souza et al. (2011) characterized nutritionally the residues of tropical fruit pulps and observed that the residue of guava pulp presented higher percentage of ashes (0.72%).

 

 

In respect to the percentage of ashes in the beverage enriched with umbu and guava pulp, in each formulation, the higher percentage is verified to the peanut extract enriched with umbu at P60;40PE (0.18%), followed by the formulations P50:PE50 (0.17%) and P40:PE60 (0.16%), respectively. As to the beverage enriched with guava pulp the higher concentration of ashes was found in formulation P40:PE60 (0.28%) followed by P50:PE50 (0.23%) and P60:40PE (0.23%) which were statistically identical.

 

Jaekel et al. (2010) verified that beverages composed of 70% soy extract and 30% rice extract (70S:30R) are better nutritional options with higher quantities of protein, lipids, minerals (estimated by the ash percentage) and fibers, over beverages composed of 50% soy extract and 50% rice extract (50S:50R) and 30% soy extract and 70% rice extract (30S:70R).

 

Proteins

 

In Table 4, the higher percentage of proteins for the beverage enriched with umbu was noted in formulations P40:PE60 and P50:PE50 (pulp:peanut extract) and the lowest in formulation P60:40PE, which means to say,  the larger the quantity of umbu pulp added to the mix, the lower is the percentage of proteins. Such was explained by Souza et al. (2010) who classified umbu as aqueous or juicy, a fruit that presents great humidity, therefore by adding more of the fruit, the quantity of water also increases and, consequently, proteins are dissolved. According to Souza et al. (2011) fruits in general are not potential sources of proteins, however this macronutrient is particularly found in the peel and seed of fruits. The experiment behavior was different for beverages composed of peanut extract and guava pulp as the higher percentage was found in formulation 50P:50PE, followed by formulation P60:40PE and 40P:60PE, respectively.

 

The percentage values of proteins (Table 4) in each formulation are statistically the same in formulation P50:PE50 for both beverages and its behavior is the inverse to the other formulations, which means for P40:PE60, the higher percentage is related to umbu enrichment, as for P60: PE40, the higher percentage was verified for the beverage enriched with peanut extract and guava pulp.

 

 

pH

 

Based on data displayed in Table 5, it is noticed that the pH of beverages elaborated with peanut extract and guava pulp presented higher values of pH when compared to the beverage elaborated with peanut extractand umbu pulp for the three formulations. These results are due to the fact that pH value of the chosen species to enrich the beverages are different, that is, guava pulp presents higher pH values than the umbu pulp. There is support to such situation on Brazil et al. (1995), who found pH of 3.98 for guava pulp and Gouveia et al. (2004) who found it of 3.91; as to the umbu pulp the pH values decrease from 2.21 found by Ferreira et al. (2000) to 1.38 by Paula et al. (2012); these lower values indicate the umbu pulp is more acid which justifies the lower pH of the beverage enriched with it.

 

 

Abreu et al. (2007) in his evaluation of physical-chemical characteristics of the soy based beverage from different brands with pineapple, guava, mango, passion fruit and coconut juice mix, commercialized in Brazilian markets, obtained for the guava enriched beverage pH values of 3.98 (GJ1 – soy based beverage and guava (brand A)) and 3.88 (GJ2 - soy based beverage and guava (brand B)).

 

Analyzing the pH information for each beverage elaborated in each formulation, the pH decreases as the quantity of umbu pulp increases. Umbu is considered an acid fruit (low pH) thus when its quantity increases, the pH tends to decrease. For the beverage based on peanut extract and guava pulp the higher pH is verified for the formulation P40: EP60 over the others which were the same statistically (P50:PE50 e P60:40PE).

 

Mercaldi (2006) studied soy based beverages enriched with soursop and developed in the beginning of  the  work the preparation of a standard for beverages in which it was detected that as the quantity of soursop juice increased from 2.5 to 4.90 ml, the pH values decreased from 6.05 to 4.09.

 

Acidity

 

The values regarding the total titratable acidity of the beverages elaborated with peanut extract and umbu and guava pulps are presented in Table 6. The results in respect to the acidity of both beverages in each formulation showed that the acidity of the beverage elaborated with umbu pulp increased as the quantity of fruit also increased and the quantity of peanut extract decreased. The opposite behavior was found to the pH (Table 5) in the same beverage (enriched with umbu). The beverage enriched with guava pulp presented higher acidity in the formulation 50% pulp and 50% peanut extract, followed by formulations P40:PE60 and P60:40PE, which were the same statistically.

 

 

The higher acidity of the fruits used in the mixed beverages in comparison to the pure peanut extract (acidity = 0.30, Table 2) resulted in higher acidity and lower pH in the products containing guava and umbu pulps.

 

Abreu et al. (2007) evaluated chemically and physically soy juice with tropical fruit and observed that acidity varied    between 0.14 and 0.34 while   the soy extract acidity value was of 0.06 which confirmed the pH value found in the experiments.

 

Analyzing the acidity for each formulation, the P40:PE60 presents low acidity for the beverage formulated with guava pulp (0.43%) over the one enriched with umbu pulp (4.12%). The remaining formulations presented guava enrichment as the least acid statistically.

 

Humidity

 

In Table 6 the mean values for humidity are presented (%W_w) of two beverages elaborated with peanut extract and enriched with guava and umbu pulp. The humidity for the beverage elaborated with umbu pulp was higher in 1.11% compared to the guava pulp. According to Taco (2011), the humidity of the fruit umbu is of 89.3% and of its frozen pulp 90.20%. For the red guava such value is of 85% and the pulp is of 88.33%, according to Freire et al. (2008).

 

Analyzing the influence of formulations in the amount of humidity, it noticed the statistical equality between formulations during the experiment which indicates that humidity was not influenced by these factors.

 

Caus et al. (2008) elaborated beverages based on soy hydrosoluble extract with fruit pulp and noted that the humidity of the soy beverage, variant CD 206, with strawberry was of 83.16%; on the other hand, the passion fruit enriched beverage reached 82.79%. Pettri (2010), on the same topic, found studies with peanut extract for formulations of powder milk (0.2 and 4% powder milk) with humidity of 77.12, 76.15 and 75.66%, respectively.

Both the beverages  here analyzed in  their three formulations presented quantities of protein expressively inferior to the pure peanut extract (2.46%). The quantity of both ashes and acidity was larger in the beverage enriched with guava pulp over the umbu pulp. The pH for the beverage elaborated with peanut extract and guava pulp presented higher values than the combination of peanut extract and umbu pulp for the three formulations after 150 days of storage.

The authors have not declared any conflict of interest.