Preparation of sponge cakes with tahini pastes

There is a growing interest in health aspects of food, including functional food products with specific physiological functions of health relevance. Nuts and oilseed are regarded as natural functional foods. The addition of nuts and oilseed could improve the nutritional quality of bread and bakery products since nuts and oilseed are rich in proteins, alimentary fibre, fats (unsaturated fats principally), minerals and vitamins, especially Mg, E, A, B 1 and B 2 [8, 9]. Nuts and oilseed are an excellent source of other bioactive components, such as phytochemicals (phyotsterols, phenolic acids, flavonoids, stilbenes, and carotenoids). The total phenolic constituents probably contribute to the total antioxidant capacity of nuts and oilseed [4]. Moreover, scientific investigations have demonstrated that nuts and oilseed have beneficial effects on health, above all on chronic non-communicable diseases, such as coronary heart disease, diabetes, hypertension and obesity [4, 5, 7]. Based on the high nutritional value of nuts and oilseeds are conduct research on their use in view of the paste in bread [3, 6].

Tahini is a traditional product, mainly used in the production of halva [2]. The paper presents preliminary results on new application of traditional tahini, that will give possibility for better utilisation and popularisation of the product for healthier diet.

In consequence, the aim of the present research was to analyze the influence of the peanut and sunflower pastes /tahinis/ on the physical and sensory characteristics of the sponge sucrose-sweetened cakes, and the degree of liking by consumer acceptance tests, to know the possibility of elaborating high-quality sucrose-sweetened sponge cakes.

Materials and Methods

The standard raw materials - wheat flour type 500, granulated sugar, eggs, used in our investigations, are authorized by the Ministry of

Health Two types of tahini (sunflower, peanut) are used. The peanut and sunflower pastes /tahinis/ were delivered by “Kentavar–Ltd” company, Stara Zagora. A control sample of sucrose-sweetened with cake batter was included in the studying. The mixture for the sucrose-sweetened sponge cake (batter-control) was prepared following a traditional technology and formulation [1] as double mixing procedure by partitioning whipping of whites and yolks of egg was used. The developed recipe composition of sponge cakes with an additive of paste /tahini/ was prepared by the replacement of egg yolk with two types of tahini in quantity 15 % and 30%. Each sponge cakes batter with a mass of 95 g and was poured out in metallic forms and baked in an electric oven (Rahovetz - 02, Bulgaria) for 30 min at 180oC. The sponge cakes were prepared in laboratory conditions.

The specific gravity of the sponge cake was calculated by dividing the weight of a standard cup of batter by the weight of an equal volume of distilled water according to AACC Method 10-95 at batter temperature (20.7 ± 0.5°C). The physical characteristics of sponge cakes were measured two hours after baking. The volume was determined by small uniform seed displacement method Method AACC 10-05 2000 and the porosity according to the method of Yackoby (BDS 3412-79). The porosity of sponge cake was defined as the ratio between the volume of the air-pockets in the cake crumb and the volume of the crumb. The porosity determination was done using a cylinder driller – a device of Zhuravljov (BDS 3412-79). The specific volume was expressed as the ratio between the sponge cake volume and its mass. The water-absorbing capacity of the sponge cake was measured by the method of determination of biscuits swelling according BDS 15221-81. For the determination of the sponge cake structure were done photographs of cross sections of the half-cut cake. The indices of the structural and mechanical properties of the sponge cake crumb such as shrinkage and springiness were determined with automatic penetrometer (model DSD VEB Feinmess, Dresden, Germany). The total moisture of the samples was determined after drying of the sample at 105 °C up to the state of a constant mass according standard method (BDS 3412-79, BDS 5313-85).

Descriptive test for quantitative sensory profiling (ISO 6564 and ISO 6658) is applied to characterise the sensory characteristics of the sponge cakes (shape, colour, cells size and uniformity, odour, sweetness, aftertaste, crumb tenderness), 6 hours after baking. A panel of thirteen experienced degustatiors was selected to guarantee the evaluation accuracy. The intensity of each sensory characteristic was recorded on a ten-point linear scale after one hour’s orientation sessions of the panelists where they specified terminology and anchor points on the scale. The coded samples were shown simultaneously and evaluated in random order among panelists.

Depending on the type of the studied characteristic from 3 to 13 repetitions of each measurement were done. A method was used for the valuation of results with a level of statistical significance p < 0.05.

Results and Discussion

The recipe compositions of the control sample and the investigated cakes containing an additive of paste /tahini/ are presented in Table 1.

Table 1 - Sponge cake batters formulations

Ingredients	Amount based on flour weight, %:
	control sample	with 15 % tahini	with 30 % tahini
Yolk of egg	43.23	36.75	30.26
White of egg	96.77	96.77	96.77
Refined granulated sugar	83.87	83.87	83.87
Wheat flour type 500	100.00	80.00	50.00
Paste /tahini/ - type sunflower or peanut	-	6.48	12.97

Table 2 - Physical characteristics of the sponge sucrose-sweetened batters and cakes

Physical characteristics1	Sponge sucrose-sweetened cake type
	Control sample	with 15 % sunflower tahini	with 30 % sunflower tahini	with 15 % peanut tahini	with 30 % peanut tahini
Specific gravity (for batter) 2	0.72 ± 0.03	0.81 ± 0.01	0.81 ± 0.01	0.80 ± 0.01	0.83 ± 0.01
Volume, cm3	244.40 ± 4.93	208.00 ± 4.47	208.00 ± 4.47	232.00 ± 11.60	192.00 ± 8.37
Specific volume, cm3/g	3.00 ± 0.09	2.63 ± 0.06	2.63 ± 0.06	3.03 ± 0.34	2.47 ± 0.13
Porosity, %	68.85 ± 3.34	59.27 ± 3.70	63.70 ± 3.10	54.07 ± 6.73	54.07 ± 5.62
Spinginess, PU3	32.96 ± 2.55	23.60 ± 1.52	22.60 ± 2.04	22.60 ±2.04	29.10 ±4.72
Shrinkage, PU	86.10 ± 2.19	56.20 ± 6.57	54.80 ± 8.23	69.90 ± 6.15	67.44 ± 6.68
Water-absorbing capacity, %	327.00 ± 17.05	315.20 ± 30.34	267.80 ± 25.63	367.20 ± 1.92	315.80 ± 8.58
Total moisture, %	31.49 ± 0.36	26.90 ± 0.31	20.17 ± 0.36	23.19 ± 0.34	20.96 ± 0.08

1 The values are mean ± SD (p <  0.05).

2 The temperature of the batter is on the average 20.7 ± 0.5 о С.

3 PU - Penetrometer Units.

The most accurate evaluation of the merits of the suggested technology can be given by juxtaposing the qualitative characteristics of cakes batter for the control batter-sample and the four kinds of batter containing an additive of tahini from two types (sunflower, peanut) in quantity 15 % and 30 %, as also juxtaposing the same characteristics of the baked sponge cakes.

In this studying the sponge cake batters with two types tahini, which partially replaces the contents of the yolks, have a bigger specific gravity (0.81 ± 0.01; 0.81 ± 0.01; 0.80 ± 0.01; 0.83 ± 0.01) towards the same of the control batter-sample (0.72 ± 0.03) shown in Table 2. A reverse relationship between the batter specific gravity and the sponge cakes physical characteristics such as volume and porosity (Table 2) was established. For the sponge cake-control, which batter had a smaller specific gravity, a larger volume and bigger porosity were determined. The difference in terms of porosity and specific volume between the sponge cake-control and the sponge cakes with both tahini is significant, but at least for a cake with 30% sunflower tahini and for a cake 15% peanut tahini. In this study, the volume of the cake-control (244.40 ± 4.93 cm3) is larger than that of the cakes with both types tahini, and the largest volume of it is a cake tahini with peanut 15% (232.00 ± 21.68 cm3) and respectively the smallest volume is a cake with increased content of peanut tahini 30% (192.00 ± 8.37 cm3). Probably the large amount of fat, protein and fiber in the tahini influence this reduction in the volume of new cakes, like as similar results were obtained by other researchers (Oliete et al., 2008). The data in Table 2 show that the control sample had greater percentage retained moisture than cakes with sunflower and peanut tahini, which lead to a difference in the indices for the structural and mechanical properties. The cake-control has a greater shrinkage (86.10 PU) and spinginess (32.96 PU) than the same for the cakes with the addition of two types of tahini.

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• Fig.1 - Photographs of cross sections of sponge cakes:

• a) without tahini – control; b) with 15% sunflower tahini; c) with 30% sunflower tahini; d) with 15% peanut tahini;

• e) with 30% peanut tahini.

| x | Не удается отобразить рисунок. Возможно, рисунок поврежден или недостаточно памяти для его открытия. Перезагрузите компьютер, а затем снова откройте файл. Если вместо рисунка все еще отображается красный крестик, попробуйтеудалить рисунок и вставить его заново.

Fig. 2 - Sensory profiles of sucrose-sweetened sponge cakes.

The crumb pores cells of the cakes with both types tahini had thicker walls, and they were larger and equal in size, which can be seen on Fig. 1. This fact corresponded with the same index of its sensor profile represented in Fig. 2. As a result the spinginess of the cakes with both types tahini was smaller; their crumb tenderness was also smaller, while their structure was stable at high loads, expressed by lower shrinkage in respect to sponge cake-control, most expressed in the cake with peanut tahini 30% (54.80 ± 8.23 PU). The cells of the sponge cake-control were smaller and almost equal, uniformly distributed in the crumb, and at the same with thinner walls (Fig. 1 and Fig. 2). That was the reason this cake to have higher water-absorbing capacity in respect to the new cakes, except the tahini cake with peanut 15%, which is higher waterabsorbing capacity (367.20 ± 1.92%) compared to cake-control (327.00 ± 17.05%). In our research was found that the cake-control and the products with tahini have approximately the same shape. The odour of the cakes with the addition of two types of tahini was more specific towards the control sample odour, and was not perceived by the sensor panelists as unpleasant. The cake-control had a crust and crumb with more pronounced light-yellow colour due to the presence of the dying components in the yolks of egg (especially carotenoids). The cakes with tahini have light brown crust and crumb with darker shades of yellow and light brown. The colour of the cake-control and the sponge cake with 15% peanut tahini is most preferred. The cake with 30% sunflower tahini has the sweetest flavour.

Conclusions

• 1.    Developed recipe composition and technology for sucrose-sweetened sponge cake with plant functional ingredients, it is only partial replacement of egg yolks with sunflower and peanut tahini in the control sample.

• 2.    The cakes with both types tahini has less spinginess, less crumb tenderness, and the structure is stable at high loads most markedly expressed with the sample with 30% peanut tahini (54.80 ± 8.23 PU). The cake with 15% peanut tahini has higher water-absorbing capacity (367.20 ± 1.92%). The cakes with tahini have light brown crust and crumb with darker shades of yellow and light brown. The colour of

• 3.    The physical and sensory characteristics of the sucrose-sweetened sponge cakes and with added sunflower and peanut tahini are juxtaposed with those of the control cake-sample. On this basis, we believe that newly prepared sucrose-sweetened sponge cakes containing sunflower and peanut tahini are suitable as intermediate products in confectioneries designed for rational and dietetic nutrition.

the sponge cake with 15% peanut tahini is most preferred. The cake with 30% sunflower tahini has the sweetest flavour.