Evaluation of the Sensory Quality of Sweetened Sesame Paste (Sesamumindicum)

From sesame, it is possible to obtain a creamy paste, which could represent a solution to the problem of wasteful production of this oilseed. In view of the above, the sensory quality of sweetened sesame paste formulated with added bovine blood plasma as a surfactant for possible use in confectionery was assessed in the present investigation. A completely randomized experimental design was used, under a multilevel 2x2x4 factorial structure at half fraction to rule out effects of similar treatments. It was evaluated the effect of factors (80 and 70% sesame paste, syrup (water + sugar + glucose) at 20 and 30% and bovine blood plasma at 0.75,1.0,1.25 and 1.5%) on the sensory responses of the 8 formulations. The sensory evaluation of the different treatments was carried out through preference and acceptance tests; the treatment with 70% of paste, 30% syrup and 1% plasma was the most widely accepted. The best treatment was T2 followed by T6. T8 showed significant differences in the parameters evaluated when compared to other treatments, and in turn had the lowest acceptance in the evaluated attributes. In general, treatments with a higher percentage of syrup had greater preference and acceptance for the same blood plasma content. In addition, 1% plasma is sufficient in the formulation of the paste, and higher concentrations make it perceptible, making the consumer reject the product. Keyword-Sesamumindicum L., Blood Plasma, Surfactant, Sensory Analysis.

low-cost protein, since this is one of its main components, and also has functional properties for application in the food industry, which is why it is already being used in some countries [19].
On the other hand, the addition of various flavours, spicy touches, sugars and salts to the traditional sesame paste has become a traditional practice by the farmers of the Montes de María. One of the most commonly used ingredients is sucrose, which undergoes heat treatment until it is converted into a viscous fluid. In this study, a mixture of sucrose and glucose was used due to its water solubility properties. Glucose is the most abundant monosaccharide in nature, it is present in fruits such as apples, strawberries, grapes and vegetables such as onions and other products such as honey. In addition, its importance lies in the fact that it is an essential and multitransformable raw material for obtaining other products. It is an eldosa belonging to the hexose family, which is obtained from the complete and controlled hydrolysis of starch and gives rise to other sugars such as sucrose and fructose. It is an important form of carbohydrate in the metabolism of cells [20]. Therefore, the objective of the present investigation was to evaluate the sensory quality of a sweetened sesame paste formulated with added bovine blood plasma as a surfactant for possible use in baking.

A. Raw material
Sesame (S. indicum L.), a white 70 than variety from the mountainous region of the Municipality of Córdoba, Bolívar (Colombia), was used. Lyophilized bovine blood plasma supplied by Tecnas S. A. (Medellín, Colombia) was used. The other inputs used in the formulation (sodium chloride, sucrose and glucose) were obtained from supermarkets in the city of Cartagena de Indias, Colombia.

B. Technological elaboration of sesame paste
The methodology for the production of technified sesame paste, previously reported [1,14], was used. To make the paste, 1000 g of sesame seeds was cleaned and husked, then immersed in 6 L of water at room temperature for 12 h. The soaked seeds were squeezed and husked, then immersed for 5 min in a 23 % w w -1 saline solution (each 1000 g in 8 L of solution). In order to separate the shells and other foreign elements, the immersion of the seeds in the saline solution was repeated three times, then taken from the surface of the solution and washed with water five times to remove the sodium chloride. Later, the seeds were squeezed to reduce their surface water content and then used for the roasting process in this study. 250 g of wet peeled seeds were roasted at a temperature of 140°C in a Challerger HE 2495 compact oven for 30 min with stirring. It was immediately balanced at room temperature to avoid overheating. The roasted seeds were ground in a Corona brand grain mill twice.

C. Syrup elaboration
Sugar and water in a ratio of 1:1 were used to make syrup and liquid glucose was added to 3% of the total sucrose weight. After having the syrup ready, and with the help of a D-500 -LB Pro Disperser, the sesame paste and 50% plasma were mixed for 30 s at 2 rpm. Afterwards, the syrup was slowly added between 2 and 4 rpm for 2 minutes and the remaining 50 % of plasma was mixed for 3 minutes, achieving a good homogenization. It is important to note that the syrup should not be hot when added to the paste, as it would facilitate the separation of oil from sesame paste.

D. Experimental Design
A completely randomized experimental design was used, using factors (with their respective levels): sesame paste (80 % and 70 %), syrup (20 % and 30 %) and blood plasma of bobbin (0.75 %; 1.0 %; 1.25 % and 1.5 %), for a total of 8 experimental formulations, with three replicates of each treatment, for a total of 24 experimental units. The response variables for evaluating the sensory quality were the preference and acceptance tests (general acceptability, taste, smell, texture and appearance) of the sugar paste. The formulations used shown in Table 1 were selected based on preliminary testing.  From the results obtained, it can be inferred that acceptance and preference vary according to the percentage of plasma and syrup; that is, as the concentration of bovine plasma increases and the proportion of syrup decreases, the preference of samples declines considerably. Additionally, it is observed that 1% incorporation of plasma in the formulation of the pastes is sufficient to create a product with sensorial characteristics acceptable to the consumer, since the formulations with these quantities were the ones that obtained higher scores in both types of test (T2 and T6), being this plasma content sufficient in the formulation of the paste, since higher concentrations make it perceptible, generating consumer rejection towards the product. In contrast, Benitez et al., [23] who claimed that the inclusion of blood plasma in a flour biscuit did not affect the sensory characteristics of the product, resulting in high acceptability.Instead, Izasaet al., [24] reported that the production of salami without bovine plasma was the one that best reported the acceptability of sensory characteristics such as smell, taste and hardness, this could be due to the presence of lipidic compounds, which would affect gelification behavior, agent-surface interaction and protein concentration.
Julio et al., [18] evaluated the quality and acceptability of sausages formulated with bovine blood plasma and sesame paste, finding that the addition of blood plasma improves yield, increases protein content and reduces the fat content, without having a negative effect on acceptability.

III. CONCLUSIONS
The inclusion of blood plasma at 1% may represent an improvement in the sensory quality of foodstuffs such as sesame paste. It was also evidenced that the best treatment was T2, which would serve as a starting point for the formulation of pastry products. It is concluded that the acceptance and preference of pastes varies according to the percentage of plasma and syrup, possibly due to the presence of lipidic compounds of sesame paste, which would affect the gelling behaviour.