Consumer acceptance and sensorial analysis of bread with grape seed flour

. Grape seed flour from grape marc, a waste product obtained during winemaking, was analyzed for use in bread production due to its potential health benefits. This study evaluated the consumer acceptance and physical properties of bread made with varying quantities of grape seed flour. Dough and breads were prepared using different levels of replacement of wheat flour with grape seed flour (0 to 9 %). The method used for the research was that of the scoring scale, and the marks given by the 15 properly trained panelists indicated that a percentage of 5% grape seed flour by the indirect method leads to statistic characteristics close to those of black bread regarding Standard SR 878/1996.


Introduction
consumer preference for improved white bread, through the use of cereals and other seeds as functional ingredients rich in dietary fiber, antioxidants and other valuable nutrients [4,5,6,7]. Improving bakery products with grape seed powder is an effective way to improve nutritional characteristics, especially through the intake of fiber, K, Mg, Ca [8,9,10]. On the other hand, consumer acceptability is a sine-qua-non condition for launching such new products. In what follows are presented the research method and the results obtained following a test performed in March 2019 at the Transylvania University of Brasov.
Main recipe reported to 1kg flour contains 700ml water, 20g yeast, 20g salt and 60g sugar.
11 samples of bread, weighting 600g each were made using direct and indirect method, by adding different quantities of grape seed flour (GSF), as following: x P0d: 0% -represents the control bread sample with direct method; x P1d: 3% -represents the bread sample with direct method with an addition of 3% GSF; x P2d: 5% -represents the bread sample with direct method with an addition of 5% GSF; x P3d: 7% -represents the bread sample with direct method with an addition of 7% GSF; x P4d: 9% -represents the bread sample with direct method with an addition of 9% GSF; x P0i: 0% -represents the control bread sample with indirect method; x P1i:3%-represents the bread sample with indirect method with an addition of 3% GSF; x P2i:5%-represents the bread sample with indirect method with an addition of 5% GSF; x P3i:7%-represents the bread sample with indirect method with an addition of 7% GSF; x P4i:9%-represents the bread sample with indirect method with an addition of 9% GSF; x PN -represents the control black bread sample for comparison. Technological process by direct method followed next phases: 9 raw material conditioning (heating at 20°C, dosing, yeast activation); 9 mixing (mixer Silver 50 NOVAPAN company, vat capacity: 55l, mixing arm speed: 80 rot/min, mixer vat speed: 25 rot/min, mixing time: 25min); 9 fermentation I in mixer (35 min, at 20°C temperature); 9 division with divider SQSA/Vitella, in 10 equal pieces of 500g dough; 9 fermentation II for 35 min at 33°C and 80% humidity; 9 baking in the oven (AST/ Tagliavini -Italia) for 45 min at 220°C; 9 Technological process by indirect method followed next phases: 9 raw material conditioning (heating at 20°C, dosing); 9 leaven preparation: 40% flour, 82% water, mixing time: 10min, fermentation time: 4h; 9 mixing (60% flour, 18% water) (mixer Silver 50 NOVAPAN company, vat capacity: 55l, mixing arm speed: 80 rot/min, mixer vat speed: 25 rot/min, mixing time: 25min); 9 fermentation I in mixer (35 min, at 20°C temperature); 9 division with divider SQSA/Vitella, in 10 equal pieces of 500g dough; 9 fermentation II for 35 min at 33°C and 80% humidity; 9 baking in the oven (AST/ Tagliavini -Italia) for 45 min at 220°C.

Research method for sensorial analysis of bread samples
The scoring method is the use of requirements to assess the intensity of a sensory property or characteristic (sensory attribute). This method is widely applied and is used for the quantitative evaluation of a set of sensorial properties (appearance, smell, taste, color, etc.) of food [11,12]. The first stage of the sensory method is to establish the team of evaluators (panel), by selection based on the questionnaire, followed by the training of the panel for the sensory evaluation of the products to be tested.
The second stage consists in the elaboration of the sensory analysis sheet. After the individual evaluation, the sensory analysis sheets are centralized and a calculation method is applied to evaluate the results. If the evaluation panel consists of N evaluators and n is the number of sensory attributes established for evaluation, it results that each product sample will receive a total of (N x n) scores (appreciations), meaning each evaluator gives a score to each evaluation criterion (attribute) for each of the samples analyzed and tasted.
The total score (Ptot) that a sensory characteristic "i" receives from all "N" evaluators is given by formula 1.
Where (Pind i)j is the individual score given by the evaluator "j" for the characteristic "i"; N -the total number of evaluators in the panel.
The average score given to characteristic 'i' is given by formula 2.
For the analysis of the sensory characteristics from the evaluation sheet, several scoring systems are used, of which we used the 5-point scoring system.
Bread samples obtained from flour mixtures with the addition of partially defatted grape seed flour (GSF) were subjected to sensory analysis using the method of assessing sensory quality by scoring.
The panel evaluations of the sensory properties of the bread samples were performed at the Transilvania University of Brasov, at the student canteen of the university. Bread samples were subjected to sensory analysis after processing, cooling and storage, so that they are in similar conditions of consumption as the usual bread assortments in the bakery sales network. Bread samples were evaluated one day after baking, after cooling and storage at ambient temperature. The selection, preparation and monitoring of the persons who participated in the sensory evaluation of the bread samples were made in compliance with the provisions of the standards. ISO 8686-1 and ISO 8586-2 (Sensory analysis -General guidance for the selection, training and monitoring of assessors, Part 1: Selected assessors and Part 2: Experts).  The main criteria underlying the selection process of each evaluator in the panel were the following: scientific interest and motivation, sincerity in reporting sensations, the ability to differentiate the specific characteristics of the evaluated product (bread), health, ability to memorize and to communicate sensory impressions. Taking into account these criteria, the pre-selection questionnaire of the evaluators from the panel was elaborated (Fig. 2.). Each evaluator completed the individual sensory analysis sheets, with slices of bread from each bread sample analyzed, for comparative tasting and bread sections for comparative analysis of the appearance and texture of the samples. Experimental samples of bread with the addition of partially skimmed grape seed flour were analyzed sensorial, comparatively, both to white bread and to black bread, and between them, to determine the optimal percentage of acceptable ingredients in terms of sensory view to be added to white bread in order to achieve a product with functional potential.  For the 10 characteristics established in the sensory evaluation of the bread samples, equal importance factors were established, thus interpreting the results using the arithmetic mean of the scores received by each sample. This simplified calculation method was chosen as it is a comparative analysis in the development process of a new bakery product. Table 1. describes the sensory attributes and the score for each attribute used in the sensory assessment sheet.

Results
Following the experiments performed on a group of 15 panelists, the values of the average scores obtained at the sensory evaluation that were obtained are shown in table 2.
In figure 3 are represented graphically comparatively the results regarding the characteristics: crumb color, uniformity of crumb pores, crumb softness and crumb friability.
In figure 4 are represented graphically comparatively the following characteristics: the bitter, salty and sour flavors, the intensity of the specific flavor and the persistence of the aroma after chewing and swallowing. The analysis of the table shows the change in shell color, core color, core pore uniformity, core flexibility, core friability, bitter taste, salty taste, sour taste, specific aroma, aroma persistence after chewing and swallowing with the change in the amount of seed flour in the recipe.     Figure 3 shows the increase of the values corresponding to the color of the core directly proportional to the GSF content variant 5% the indirect method, being similar to that of black bread. The uniformity of the pores increases with the increase of the addition of GSF variant 5% indirect method, being similar to that of black bread. The friability of the core increases with the increase of the addition of GSF, the 5% indirect method, being similar to that of black bread.

Discussions
The results shown in figure 4 also indicate that the taste indicators are close to those of black bread with GSF additions around 5% value.
Future research will be conducted on the use of grape epicarp as an addition to bread making recipes. Theoretical and experimental analyzes will be performed regarding the chemical composition, the nutritional profile, the rheological behavior of the dough and the sensory analysis [13,14,15]. Different degrees of replacement of wheat flour with grape epicarp flour are considered, such as: 5%, 7.5%, 10%, 12.5%.

Conclusions
Improving bakery products with the addition of GSF is a fast and efficient method of increasing the content of minerals and fibers. The paper studied the level of consumer acceptability for different degrees of replacement of GSF for the 2 technologies, direct and indirect method.