Technology of biscuit semi-finished products using recycled pumpkin seeds

A possibility and expediency of pumpkin seeds flour utilization for production of biscuit semi-finished product was studied; the influence of the flour on consumer properties of the product was investigated. Studies were conducted on organoleptic and physicochemical indicators of the finished biscuit semi-finished products. Grounding on the implemented studies a new production technology of pumpkin seeds flour based biscuits was developed, shelf life, biological, and nutrition value were identified. It was established that the optimal ratio of pumpkin seeds flour and starch is 90.5±0.5% to 9.5±0.5%. It was established that after consuming 100 g of the biscuit with a complete substitution of wheat flour to the gluten-free mixture 44% of daily need in magnesium, 50% - in selenium, 39% - in copper, 48% - in phosphorus, 46% - in manganese, 36% - in vitamin B9, and 36% - in linoleic acid is satisfied.


Introduction
Flour confectionery remains an integral part of any cuisine and plays a great role in nutrition of humanity.
Most flour confectionery is characterized by poor contents of protein, essential amino acids, macroand microelements, vitamins, and other vital nutrients, as well as by a high caloric content. Regarding current consumer requirements flour confectionery needs to not only be a mere calorie carrier but to provide a specific functionality.
A substantial part of food products is taken by products devoid of grain crop protein which causes an autoimmune chronic Gee's disease [2].
Due to that the search for raw materials, which could allow creating gluten-free products of high quality possessing a balanced chemical content and high nutritional value, comes to the forefront. Ways of production of gluten-free confectionery were developed with the use of various flour types, such as triticale, rice, buckwheat, corn, fat-free flour from grape, watermelon, thistle fruit seeds; vegetable, fruit and vegetable and berry purees, pastes and powders; grain and groats conversion products [3][4][5][6][7][8][9][10][11][12]. Currently pumpkin flour, which is produced during the processing of its seeds, is of special interest. Chemical contents of pumpkin seeds are characterized by a high composition of vitamins, macro-and microelements, essential amino acids and polyunsaturated fat acids.
The purpose of this paper is to develop a technology for a biscuit semi-finished product with a complete substitution of wheat flour to pumpkin seeds flour.
In compliance with the mentioned purpose the following tasks were identified:  to investigate organoleptic and physicochemical indicators of biscuit baked products with a complete substitution of wheat flour to pumpkin seeds flour with varying ratio of starch from a dry mixture mass and to identify optimal ratio of pumpkin seeds flour and starch from dry mixture mass;  to develop a technology of a biscuit with a complete substitution of wheat flour to a gluten-free mixture;  to conduct a complex evaluation of the quality of new biscuit baked products. Pumpkin seeds flour and biscuit of recipe #1 according to a collection of flour confectionery and bun products [13][14][15][16][17] were chosen as the object of investigation. According to commonly known methods the following physicochemical indicator were identified:  Gelation temperature -by heating the flour suspension to the temperature of 55-95°C with a 10°C step and subsequent centrifuging of a cooled sample during 10 minutes with a 3000 revolutions per minute speed.  Density of baked gluten-free products -as a ratio of mass to the volume of a baked semi-finished product's fragment.  Baking losses of gluten-free products -by a ratio of difference between test preparation mass and baked semi-finished product to test preparation mass;  Swelling capacity of crumb of baked gluten-free products -according to a method developed by Saint-Petersburg State Science and Research Institute of Baking Industry;  Water activity of baked gluten-free products using a device Aqulab Pawkit. A generalized organoleptic indicator was identified by (1).

Methods of investigation
where p i is a value of i organoleptic indicator; k i is a value of ponderability coefficient of i organoleptic indicator. Coefficients of ponderability were established depending on significance of an organoleptic indicator (table 1). The sum of all the coefficients was set as 20. This way, with a 5-point scale of organoleptic indicators evaluation, the maximum value of a generalized organoleptic indicator amounts to 100. Organoleptic analysis of gluten-free biscuit products was conducted according to a 5-point scale. For a comparative organoleptic evaluation a system of indicators was developed which includes appearance, color, texture, aroma, and taste (table 2).
Pumpkin seeds flour is a loose powder of a light-green color, no crunch is felt during chewing, which speaks for the absence of mineral admixture, taste and aroma are typical for pumpkin seeds.   The autolytic activity indicator of pumpkin seeds flour complies with the indicator of premium grade wheat flour. An increased acidity of pumpkin seeds flour (5 and a half times more than of wheat flour) is explained by the presence of a great amount of organic and polyunsaturated fat acids, which will contribute to intensification of sucrose hydrolase process during biscuit dough formation.
Thus, pumpkin seeds flour does not possess baking properties of wheat flour, however, it may be recommended to use for confectionery industry as the main and additional component of gluten-free mixture, during creation of functional products, for flour confectionery products that do not require a high content of gluten, like biscuit.
Gluten-free mixture based on pumpkin seeds flour and method of adding eggs were taken as factors that influence on quality of biscuit semi-finished products and especially on porosity of the finished products.
Gluten-free mixture used for production of biscuit semi-finished products consists of pumpkin seeds flour and starch.
Investigation of organoleptic indicators and humidity of biscuit semi-finished products was conducted based on gluten-free mixture samples varying ratio of starch from 0 to 20% with a 2% step.
On the grounds of experimental data regression equations were obtained characterizing dependency of generalized organoleptic indicator (2) and humidity of biscuit semi-finished products (3) on starch content (x, ratio) in a gluten-free mixture.   Analysis of revealed dependencies showed that ration of pumpkin seeds flour and starch 90.5±0.5% to 9.5±0.5 % is close to optimal and provides satisfactory quality of biscuit semi-finished products.
Sectional view of pumpkin seeds flour based biscuit sample is demonstrated at Fig. 3. It is evident that the baked biscuit sample had a small rise and sank after baking, which speaks for a weak stability of biscuit dough.  Stored gluten-free biscuit semi-finished products were evaluated according to generalized organoleptic indicator, water activity and mass as well as organoleptic indicators grounding on which shelf-life period of baked products can be revealed.
Organoleptic indicators of the second sample during storing were substantially superior over those of the first sample due to finely-porous and elastic structure of the biscuit.
On the basis of experimental data regression equations were obtained characterizing dependency of water activity indicator (4) and mass (5) on storing duration (days).   Water activity of biscuit semi-finished products during storing decreases hyperbolically down to the value of 0,8, the mass of biscuit semi-finished product made with a method of separate addition of eggs and boiling protein with hot syrup insubstantially decreases after baking. At the same time, the process of staking that is related to retrogradation of starch is almost not observed, the products stays soft and elastic.
Biscuit semi-finished products based on pumpkin seeds flour satisfies the human need for tryptophan amino acid, score of which equals 100%. Limiting acids in the studied semi-finished product are lysine and threonine.
Expediency of pumpkin seeds flour utilization in a biscuit semi-finished product technology was proved by investigation of its nutritional value (table 4) and mineral elements, vitamins and polyunsaturated fat acids composition.

Conclusion
Technological characteristics of pumpkin seeds flour were investigated, on the basis of which the studies were conducted on the main organoleptic and physicochemical indicators of biscuit semi-finished products with a complete substitution of wheat flour to pumpkin seeds flour with variation of starch ratio.
It was established that the optimal ratio of pumpkin seeds flour and starch is 90.5±0.5% to 9.5±0.5%. After consuming 100 g of the biscuit with a complete substitution of wheat flour to the gluten-free mixture 44.48% of daily need in magnesium, 49.56% -in selenium, 38.95% -in copper, 48.29% -in phosphorus, 46.40% -in manganese, 35.74% -in vitamin B9, and 36.04% -in linoleic acid is satisfied.