Effect of high-oleic sunflower oil and other pro-health ingredients on physical and sensory properties of biscuits

Abstract

The purpose of this work was to determine the possibility of using high-oleic sunflower oil for the production of biscuits. Additives (inulin, β-glucan, lecithin) were introduced into the formulation to improve the quality and nutritional properties of products.

Additives had a positive impact on the volume growth of products with oil, although the effect was lower than of biscuits with shortening. The breaking strength of biscuits with oil was greater than that of the ones with shortening, except products with the addition of lecithin. Inulin affected lightness of color, whereas replacement of shortening with oil darkened the color and caused the total color difference (ΔE) to be significantly different from that of the control sample. The fat migration was maximum from products in which oil was used without additives. Based on sensory evaluation, biscuits with oil – inulin and lecithin – which in the evaluation of overall quality scored 8/10 and 7.9/10, respectively, proved closest to the control sample. It was observed that the sensory quality of cookies significantly improved with the inclusion of lecithin.

El propósito de este trabajo fue determinar la posibilidad de la utilización de aceite de girasol alto oleico para la producción de galletas. Se introdujeron aditivos (inulina, β-glucano, lecitina) en la formulación para así mejorar la calidad y las propiedades nutritivas de los productos.

Los aditivos tuvieron un impacto positivo en el crecimiento del volumen de los productos con aceite, aunque menor en las galletas con grasa alimentaria. La dureza de las galletas con aceite al romperse fue mayor que la de las galletas con grasa alimentaria, excepto con los productos donde se había añadido lecitina. La inulina afectó a su color claro, mientras que al remplazar la grasa alimentaria con aceite el color oscureció y la diferencia total de color (ΔE) fue significativamente distinta en comparación con la muestra control. La mayor migración de grasa fue en los productos en los cuales se utilizó aceite sin aditivos. En base a la evaluación sensorial más parecida a la muestra control, esta resultó ser la de las galleras con aceite, inulina y lecitina, en cuya evaluación la calidad total obtenida fue respectivamente 8/10 y 7,9/10. Se observó que la calidad sensorial de las galletas mejoró significativamente cuando se incluyó lecitina.

Keywords:

• biscuits
• nutritional value
• high-oleic sunflower oil
• texture
• PCA
• inulin
• β-glucan
• lecithin

Palabras clave:

• galletas
• valor nutricional
• aceite de girasol alto oleico
• textura
• PCA
• inulina
• β-glucano
• lecitina

1. Introduction

In the face of exacerbating problems of civilization conditions such as cardiovascular diseases and obesity, limiting the consumption of fats, in particular fats rich in saturated fatty acids (SFAs) and trans fatty acids (TFAs), is recommended (WHO).

According to a study conducted in 2013, 29.5% of biscuits available in the Polish market contained hydrogenated fat (Onacik-Gür, Żbikowska, & Kowalska, 2014). During hydrogenation, oil changes its consistency from liquid to solid. Unhealthy forms of TFA isomers may be formed as a result of this process (Valenzuela & Morgado, 1999; Żbikowska, 2011). Other countries are prohibiting this kind of fats or regulating the limit of the content of TFA in food. In addition, in several countries, information about TFA content is required on packaging (Downs, Thow, & Leeder, 2013). Hence, food producers use shortenings, which are based on palm fat rich in SFA, mainly palmitic acid. Hydrogenated fat and palm fat are solid at 35°C. Solid fats (solid phase content) have a positive effect on the aeration of pastry products and on their sensory properties (Kanagaratnam, Hoque, Sahri, & Spowage, 2013; Ribeiro, Grimaldi, Gioielli, & Gonçalves, 2009). Both TFA and SFA have high melting temperatures. However, high consumption of these fats has adverse effects on the cardiovascular system by increasing LDL cholesterol in blood (EFSA, 2010). Thus, to reduce the risk of heart disease, more liquid oils rich in unsaturated fatty acids should be consumed. High-oleic oils are good for the cardiovascular system as they reduce the LDL fraction of cholesterol in blood (Allman-Farinelli, Gomes, Favaloro, & Petocz, 2005). In the case of pastry products, the change from a solid to liquid fat adversely affects quality by increasing the hardness and decreasing the sensory quality (Jacob & Leelavathi, 2007). The improving awareness of consumers about the health benefits of vegetable oils consumption may foster better nutritional choices even if the quality of products is worse (Tarancón, Sanz, Fiszman, & Tárrega, 2014).

Food products are more commonly enriched in high-nutritional ingredients these days. Pro-health components such as inulin and β-glucan may lower the LDL cholesterol fraction in blood (Davidson et al., 1991; Davidson & Maki, 1999). These ingredients may be used as fat replacers. Nevertheless, they very often have a negative impact on the sensory properties of products (Laguna, Primo-Martin, Varela, Salvador, & Sanz, 2014; Piñero et al., 2008).

Inulin is a soluble carbohydrate belonging to a group of compounds called fructans. It is not digested in the upper gastrointestinal tract, but fermented by bacteria in the large intestine (Davidson & Maki, 1999). In addition, inulin is classified as a prebiotic, which promotes the growth of beneficial gut bacteria. It improves health as it has the ability to counteract osteoporosis, colon cancer, metabolic disorders associated with obesity, and heart disease (Gibson & Delzenne, 2008). β-glucan is a water-soluble polysaccharide, which has a number of health advantages such as lowering cholesterol, improving lipid metabolism, and preventing heart disease and diabetes. Furthermore, it is a prebiotic similar to inulin (Hu, Zhao, Zhao, & Zheng, 2014). Another desirable component of food products is lecithin, a blend of phosphatidylcholin and other phospholipids, that has a beneficial effect on the human body. Phosphatidylcholin is responsible for the transport of lipids and is essential to proper functioning of the liver (Canty & Zeisel, 1994).

The primary aim of this study was to determine the possibility of using the high-oleic sunflower oil for the manufacture of biscuits. In addition, some biscuit recipes were made with different additives (inulin, β-glucan, lecithin) in order to improve the quality and nutritional properties of the resultant product.

2. Materials and methods

2.1. Materials

The dough was made of whole meal flour type 2000, sugar powder, and baking powder purchased in a local market. Moreover, high-oleic sunflower oil and soy lecithin received from Zakłady Tłuszczowe Kruszwica (Bunge, Poland) were used. Inulin (Orafti®HPX from Beneo-Orafti S.A., Belgium, inulin content – 100%, DPav ≥ 23) and β-glucan prepared from barley (Vitacel®BG 300 from J. Rettenmaier & Sӧhne GmbH, Germany, β-glucan content > 23%) were added to the recipe (Table 1).

Table 1. Biscuits recipes.

Tabla 1. Recetas de galletas.

Ingredients [g]	Shortening (control)	Oil	Oil + lecithin	Oil + inulin	Oil + inulin+ lecithin	Oil + β-glucan	Oil + lecithin + β-glucan
Flour	100
Sugar	34
Baking powder	2
Water	16	16	16	16 (+addition)	16 (+addition)	16 (+addition)		16 (+addition)
Shortening	46	−	−	−	−	−		−
Oil	−	46	46	28	28	28		28
Lecithin	−	−	1.5	−	1.5	−		1.5
Inulin	−	−	−	8	8	−		−
β-glucan	−	−	−	−	−	8		8

Inulin and β-glucan were used as fat replacers in biscuits, following which the oil content was decreased by 40%.

2.2. Preparation of the biscuits

The biscuit dough was sheeted to a thickness of 0.5 cm and cut into squares with a side length of 4 × 4 cm. The biscuits were baked in a convection oven Unox (type: BakerTop4 600×400, Italy) for 15 minutes at 165°C. Once cooled, the biscuits were packed into polyethylene bags and stored at room temperature (20 ± 2°C) for four and eight weeks, without any access to sunlight.

2.3. Physical characteristics of biscuits and dough

Density of dough was calculated based on the following equation:

(1)

where D_d is biscuit dough density, M_s is the weight of dough and weighting bottle, M_w is the weight of a weighting bottle, and V_w is the volume of the weighting bottle. The analyses were carried out in two replicates.

Once baked, height and width of the biscuits were measured by placing them edge to edge and by stacking one above the other. The dimensions were measured using a digital caliper with an accuracy of 0.01 mm. The above analysis was carried out in six replicates.

To determine the density of a finished product, the following equation was used (Rahmati & Tehrani, 2014):

(2)

where D_b is biscuit density, M_b is weight of biscuits, and V_r is rapeseed volume displaced from the bowl by the biscuits. The above analysis was carried out in six replicates.

The moisture of the product, expressed as a percentage, was determined by drying 5 g at 130°C for 60 minutes in a laboratory drier (Sakin-Yilmazer et al., 2013).

2.4. Breaking strength

The texture of biscuits was measured using a Brookfield texture analyzer (model: CT3, USA). The breaking strength (BS) was determined using a 60 mm straight-edge knife (type: TA7, part of Brookfield texture analyzer equipment TA-P-KIT2). The sample deformation was set to 30%, the trigger load was 1N, and the knife was moving at a constant speed of 0.5 m/s. The experiment was performed at room temperature (20 ± 2°C) (Kozłowicz, 2010).

2.5. Color

Instrumental superficial color of the biscuits was evaluated using a Chromameter Minolta (CR-200, Osaka, Japan) defining color parameters L*, a*, and b*. The total color difference between samples and control biscuits (shortening based) was calculated using the following equation:

(3)

where ΔE is total color difference, L_c is parameter L* of the control biscuit (shortening), L_s is parameter L* of the studied sample, a_c is parameter a* of the control biscuit, a_s is parameter a* of the studied sample, b_c is parameter b* of the control biscuit, and b_s is parameter b* of the studied sample. The value of ΔE < 3 is not visible to the human eye (Francis & Clydesdale, 1975).

2.6. Fat migration

Fat migration was determined using a filter paper. Biscuits were placed in the center of the filter paper and stored at room temperature (20 ± 2°C). After a week the diameters of the resulting stains on the paper were measured in centimeters in two orthogonal directions.

2.7. Sensory analysis

Biscuits were sensorially analyzed by means of the profile method (24 hours after baking). A group of 10 trained panelists was selected among postgraduate students who attended sensory analysis classes and passed sweet threshold tests. Each person was issued a questionnaire and marked observations on the hedonic scale. The line was unscaled with a length of 10 cm. Seven differently coded samples were distributed to the panelists including the following sensory attributes: smell – 0 not typical, 10 typical; greasiness to the touch – 0 not greasy, 10 very greasy; hardness – 0 not hard, 10 very hard; crispness – 0 not crispy, 10 very crispy; taste – 0 not typical, 10 typical; and overall quality – 0 low, 10 excellent. The left end of the line indicated the minimum and the right the maximum perceptibility of a sensory attribute. In the case of overall quality, the left end and right end of the line indicated low quality and excellent quality, respectively.

First, the evaluators examined smell of the biscuits, then they determined their greasiness by touching. Other distinct sensory attributes related to texture were evaluated as part of oral processes: hardness – the first noticeable sensation while chewing biscuits; and crispness – the impression felt after about 10 seconds (Laguna, Varela, Salvador, & Fiszman, 2013). After swallowing the biscuits, the panelists marked their taste impressions on their cards and, by summing all the properties, defined the overall quality of the products.

2.8. Statistical analysis of data

The results were statistically analyzed. Person correlation and ANOVA–HSD Tukey’s test with significance differences of P ≤ 0.05 were performed with regard to the physical properties. The results for sensory properties were compared using principal components analysis (PCA). All statistical analyses were performed with a statistical program called Statistica 10.0.

3. Results and discussion

3.1. Physical properties

No statistical differences in the density of the dough were observed among the samples (Table 2). Thus, it can be assumed that the type of fat and additives did not affect the aeration of the dough. Emulsifiers are added to shortenings to emulsify better with other ingredients and to prolong the product freshness (Stampfli & Nersten, 1995). Lecithin used in this work did not affect the density of the dough. Its influence on the density was observed after baking. The products were characterized by a density of 0.49–0.71 g/cm³. It was found that inulin addition reduced the density of the baked biscuits. In biscuits with β-glucan, addition of the emulsifier was shown to lower the density of the product (Table 2). Similar results were obtained by Manohar and Rao (1999), who observed that usage of emulsifiers decreases the density of biscuits.

Table 2. Physical characteristics and water content of the examined biscuits.

Tabla 2. Características físicas y contenido de agua de las galletas examinadas.

	Parameter	Sample type
		Shortening	Oil	Oil + lecithin	Oil + inulin	Oil + lecithin +inulin	Oil + β-glucan	Oil + lecithin + β-glucan
Physical characteristics	Dough density [g/cm^3] Ā±SD	1.23a ± 0.06	1.31a ± 0.07	1.29a ± 0.04	1.26a ± 0.03	1.27a ± 0.09	1.32a ± 0.08	1.26a ± 0.08
	Biscuits density [g/cm^3] Ā±SD	0.49a ± 0.03	0.71c ± 0.03	0.64b ± 0.01	0.55a ± 0.02	0.57a ± 0.01	0.66cb ± 0.01	0.56 a ± 0.01
	High [mm] Ā±SD	8.06b ± 0.45	6.93a ± 0.17	7.29a ± 0.16	11.01c ± 0.70	10.91c ± 0.38	9.86c ± 0.70	11.32c ± 0.38
	Width [mm] Ā±SD	56.47cd ± 1.09	55.22c ± 0.61	57.32d ± 1.43	52.83ab ± 1.59	54.10bc ± 0.87	51.32a ± 1.19	52.79ab ± 1.41
	Volume [cm^3] Ā±SD	190.00c ± 24.58	126.67a ± 5.78	143.33ab ± 2.89	166.67bc ± 5.78	159.67abc ± 4.51	143.33ab ± 15.20	179.67bc ± 17.04
Water content	Water content on first day [%]	4.15b ± 0.14	2.90a ± 0.05	3.23a ± 0.67	3.85b ± 0.12	5.49d ± 0.16	4.41bc ± 0.04	4.23bc ± 0.05
	Water content after two months [%]	3.78a ± 0.23	3.59a ± 0.04	4.26ab ± 0.11	4.99b ± 0.23	4.90b ± 0.28	5.99c ± 0.99	3.75a ± 0.71

a, b, c, d – different letters indicate statistically significant differences (P ≤ 0.05).

a, b, c, d – las letras distintas indican diferencias estadísticamente significativas (P ≤ 0,05).

Height of most biscuits with a reduced fat content was statistically different from the height of products without the addition of fibers. Products without fat replacers had lower heights. It was observed that addition of lecithin contributed to expansion of the biscuits, whereas replacement of oil with fibers, in particular β-glucan, obstructed this process (Table 2). In turn, Monohar & Rao (1999) showed that addition of emulsifiers results in the spreading of biscuits. In a study conducted by Laguna, Varela, Salvador, Sanz, and Fiszman (2012). it was also observed that biscuits with a higher fiber content showed shrinkage in width and growth in height compared with the control sample. In contrast, Jacob and Leelavathi (2007) reported that the type of fat applied affects the width of biscuits. The authors showed that biscuits in which sunflower oil was used spread the most when baked. This work showed no significant difference in width of the products depending on the type of fat added (Table 2).

Biscuits with shortening showed the maximum volume and cakes with additive-free oil showed the minimum volume. It was observed that additives such as lecithin, inulin, and β-glucan caused an increase of volume in biscuits containing oil compared with products without additives (Table 2).

Enhanced humidity on the first day after baking characterized the biscuits with shortening and reduced oil content. It could be a result of using a larger amount of water in the recipe. It was observed that in the case of biscuits whose formulation included both fiber and lecithin, humidity decreased after two months of storage, whereas it increased visibly in the remaining products (Table 2).

3.2. Textural properties of biscuits

Textural properties of biscuits are affected by the time of their storage and changes occurring in them. An increase in water activity may reduce hardness whereas oxidation of fat may increase it (Patrignami, Conforti, & Lupano, 2014).

BS of the biscuits with oil and additives increased during their storage time in contrast to products with shortening, where it decreased. Products with oil and oil with β-glucan differed from other biscuits because an increase of BS was observed in the first month, followed by a decrease after two months. BS needed to deform biscuits with lecithin, except those with inulin, was lower compared to products without this additive. The lowest value (20.4 N) was observed for biscuits with oil and lecithin on the first day after baking, and the highest was 88.5 N for biscuits with oil and β-glucan (one month after baking) (Figure 1).

Figure 1. Breaking strength of biscuits a, b, c, d – different letters indicate statistically significant differences (P ≤ 0.05).

Figura 1. Dureza de las galletas al romperse a, b, c, d – las letras distintas indican diferencias estadísticamente significativas (P ≤ 0,05).

In a study conducted by Jacob and Leelavathi (2007), it was observed that biscuits with oil were characterized by a BS twice that of products with shortening, margarine, or hydrogenated fat. This was probably because the air incorporated into oil cannot be retained, which increases hardness in short dough products (Kamel, 1994). Manohar and Rao (1999) observed that the addition of emulsifiers, in particular lecithin, had a significant impact on the reduction of compression strength. However, according to Jacob and Leelavathi (2007), addition of an emulsifier (sodium steroyl lactylate) to biscuits with oil caused the hardness to drop, whereas BS was identical to that of products containing solid fat such as shortening and margarine. Other authors have demonstrated that BS increased in biscuits with reduced fat content in which fat replacers (maltodextrin, polidextrose, β-glucan, and inulin) were used (Laguna et al., 2014; Sudha, Srivastava, Vetrimani, & Leelavathi, 2007; Zaulias, Oreopoulou, & Tzia, 2002).

3.3. Color properties of the biscuits

Maximum differences were observed in the brightness of biscuits (L* values). Biscuits with shortening were the brightest. Biscuits with inulin were characterized by high values of L* parameter. The color of these products was also the most similar to that of the control sample (Table 3). Values of L* and b* parameter tended to rise and those of a* parameter tended to fall in other products with oil to which lecithin was added.

Table 3. Total color difference (ΔE) between the control sample with shortening and other biscuits, and color parameters.

Tabla 3. Diferencia total de color (ΔE) entre la muestra control con grasa alimentaria y otras galletas, además de los parámetros de color.

	Shortening (control)	Oil	Oil + lecithin	Oil + inulin	Oil + lecithin + inulin	Oil + β-glucan	Oil + lecithin + β-glucan
ΔE	0	8.16	4.55	1.62	1.53	3.17	1.65
L* Ā ± SD	61.47d ± 1.55	53.65a ± 1.21	57.04b ± 0.99	60.32d ± 1.74	60.18d ± 2.17	58.53c ± 1.13	59.94cd ± 1.27
a* Ā ± SD	7.88a ± 0.87	9.76b ± 0.86	8.84ab ± 0.52	8.96ab ± 2.29	8.67ab ± 0.94	9.02ab ± 0.76	8.29a ± 0.80
b* Ā ± SD	16.14bc ± 0.76	14.78a ± 0.70	15.64b ± 0.73	16.55bc ± 1.04	16.38bc ± 1.04	16.45bc ± 0.96	16.6c ± 1.07

a, b, c, d – different letters indicate statistically significant differences (P ≤ 0.05).

a, b, c, d – las letras distintas indican diferencias estadísticamente significativas (P ≤ 0,05).

The obtained values of ΔE (Table 3) showed that biscuits containing oil, oil with lecithin, and oil with β-glucan were significantly different in color than the control samples, which were visible to the human eye, since the value of ΔE exceeded 3 (Francis & Clydesdale, 1975).

3.4. Fat migration

In biscuits, where the oil content was reduced by 40%, fat migration was significantly lower compared to the samples without the addition of fat replacers and comparable to the products from the control group with shortening. The addition of lecithin also tended to reduce the fat migration from biscuits, which was not confirmed by statistical analysis. Addition of β-glucan was more effective at retaining fat in a product compared with inulin (Figure 2).

Figure 2. Diameters of fat stains indicating fat migration from biscuits a, b, c – different letters indicate statistically significant differences (P ≤ 0.05).

Figura 2. Diámetros de manchas de grasa indicando la migración de grasa de las galletas a, b, c – las letras distintas indican diferencias estadísticamente significativas (P ≤ 0,05).

3.5. Correlation of the biscuits’ properties

A significant negative correlation was found between the width and BS of the biscuits after eight weeks of storage and a positive one between height and width of the biscuits. The correlation table (Table 4) shows that BS on the first day and one month after baking are positively correlated with each other (0.94). However, such correlations were not seen after two months of storage. It was found that fat migration from biscuits was negatively significantly correlated with their height. The highest products were losing the least fat (Table 4).

Table 4. The correlation between physical properties of biscuits. Underlined values are statistically significant (P ≤ 0.05).

Tabla 4. La correlación entre las propiedades físicas de las galletas. Los valores subrayados son estadísticamente significativos (P ≤ 0,05).

	BS1day	BS1 m	BS2 m	m/v	Dough	Q	%w	Fat migration	Height
BS1 m	0.94	1
BS2 m	0.62	0.63	1
m/v	0.46	0.71	0.23	1
Dough	0.61	0.76	0.60	0.86	1
Q	−0.58	−0.70	−0.74	−0.50	−0.62	1
%w	0.18	−0.10	0.38	−0.49	−0.02	0.20	1
Fat migration	−0.045	0.20	−0.41	0.62	0.18	0.05	−0.82	1
Height	0.01	−0.11	0.68	−0.45	0.01	−0.21	0.71	−0.76	1
Width	−0.47	−0.46	−0.96	−0.06	−0.44	0.69	−0.43	0.58	−0.76

BS_1day, Breaking strength on the first day after baking; BS_1 m, breaking strength one month after baking; BS_2 m, breaking strength two months after baking; m/v, density of baked products; dough, density of dough; Q, overall quality; %w, moisture.

BS_1day – Dureza al romperse en el primer día después de hornear; BS_1m – Dureza al romperse un mes después de hornear; BS_2m – Dureza al romperse dos meses después de hornear; m/v – densidad de los productos horneados; masa – densidad de la masa; Q – calidad total; %w – humedad.

3.6. Sensory quality analysis of the biscuits

Sensory quality of the biscuits is very important because it determines the acceptance of a product by consumers.

Smell

The typical smell is associated with a pleasant characteristic aroma of biscuits, while atypical smell is associated with a foreign odor. The control sample was rated the highest (7.2), followed by the biscuits with oil, inulin, and lecithin (6.6). Products with oil and β-glucan were evaluated as the least typical (5.0) (Table 5). Popov-Raljic, Mastilovic, Lalicic-Petronijevic, Kevresan, and Demin (2013) observed that cookies with the addition of inulin scored the lowest in terms of typical and pleasant smell compared with cookies with the addition of oatmeal, wholemeal flour, and carob.

Table 5. Sensory analysis results.

Tabla 5. Resultados del análisis sensorial.

	Shortening	Oil	Oil + lecithin	Oil + inulin	Oil + inulin + lecithin	Oil+β-glucan	Oil + β-glucan + lecithin
Smell Ā ± SD	7.2 ± 1.22	6.0 ± 0.81	5.8 ± 1.02	6.1 ± 0.37	6.6 ± 0.36	5.0 ± 0.72	6.0 ± 0.98
Greasiness Ā ± SD	1.7 ± 0.31	3.0 ± 0.42	1.1 ± 0.31	2.9 ± 0.12	2.0 ± 0.27	0.8 ± 0.08	0.5 ± 0.10
Hardness Ā ± SD	7.1 ± 0.82	7.5 ± 0.81	3.4 ± 0.36	7.3 ± 0.46	2.8 ± 0.17	6.7 ± 0.62	3.5 ± 0.32
Crispness Ā ± SD	5.7 ± 0.50	6.0 ± 0.53	8.1 ± 1.18	6.8 ± 0.31	5.6 ± 0.46	2.5 ± 0.18	6.2 ± 0.71
Taste Ā ± SD	8.0 ± 0.91	6.7 ± 0.28	7.4 ± 0.92	5.1 ± 0.26	7.0 ± 0.82	7.0 ± 0.69	7.0 ± 1.02
Overall quality Ā ± SD	8.0 ± 1.17	5.6 ± 0.31	7.8 ± 0.67	6.8 ± 0.41	7.9 ± 0.83	5.1 ± 0.29	5.2 ± 0.87

a, b, c, d – different letters indicate statistically significant differences (P ≤ 0.05).

a, b, c, d – las letras distintas indican diferencias estadísticamente significativas (P ≤ 0,05).

Greasiness

This attribute was evaluated by touching the biscuits. A greasy coating on fingers indicates oil migration from a product. A fat layer on biscuits was the least palpable in samples with β-glucan addition. Biscuits with inulin, despite the reduced fat content, were characterized by a similar greasiness as full-fat products, according to the sensory panels (Table 5).

Hardness

The sensation of hardness is related to the force needed to break a biscuit during the first bite (Laguna et al., 2013). It was observed that the addition of lecithin caused a decrease in the hardness of the products, which confirmed the results generated by the instrumental method. Biscuits with oil were evaluated as the hardest, and those containing oil, lecithin, and inulin as the softest (Table 5). In the study conducted by Laguna et al. (2013), it was observed that biscuits with 50% reduced fat and high wheat fiber content were the hardest. Moreover, studies by Tarancón et al. (2014) showed that biscuits with reduced fat were harder than full-fat biscuits.

Crispness

Crispness is the second sensed attribute of texture. Sensory analysis showed that the emulsifier increased the crispness of biscuits. Biscuits with oil and β-glucan exhibited the lowest crispness, whereas products with oil and lecithin exhibited the highest crispness. The studies of Laguna et al. (2013) demonstrated the highest crispness for full-fat biscuits without the addition of wheat fiber.

Taste

This attribute was evaluated after consumption of the biscuits. High rating of the “taste” attribute was associated with a typical and desirable flavor of the biscuits and low rating with the presence of foreign tastes. The biscuits with shortening and oil-containing lecithin were evaluated as possessing the most typical taste and products with oil and β-glucan as the least typical. In studies conducted by Popov-Raljic et al. (2013), biscuits with inulin scored lower in terms of typical and appreciated flavor compared with other products with different additives.

Overall quality

Overall quality is a sum of attributes – texture, taste, smell, and appearance – that affects the liking of a product (Laguna et al., 2013). Regarding the overall quality, the biscuits with shortening were considered the best (8/10), followed by those with oil, lecithin, and inulin (7.9/10) and oil-containing lecithin (7.8/10). These products were similar with regard to a majority of sensory characteristics, but had significantly different hardness. According to the overall quality evaluation, the biscuits containing β-glucan and oil without additives obtained the poorest results. In a study conducted by Tarancón et al. (2014), consumers showed greater willingness to purchase products with a higher fat content, especially those where butter was replaced by olive oil.

It was observed that the addition of lecithin reduces the hardness of products and has a positive effect on the overall quality (Table 5). Similar conclusions were demonstrated in studies by Jacob and Leelavathi (2007) and Monhar and Rao (1999). In the work analyzed by this paper, the overall quality was not significantly correlated to any of the physical factors (Table 4); Laguna et al. (2012) obtained similar results.

PCA of sensory attributes

PCA method was used to analyze the results of sensory evaluation of the biscuits with shortening, oil, and oil-containing additives. The first two principal components accounted for 70.08% of variable (loadings). The first principal component (PC1) was strongly negatively correlated to the overall quality and typical smell and positively correlated to crispness. The second component (PC2) was explained by the following variables: greasiness and typical taste.

PCA analysis indicated that products with oil, inulin, and lecithin were the closest to biscuits with shortening in terms of sensory properties. The position of scores on the PCA projection shows points corresponding to recipes for the biscuits with lecithin shifting toward the upper right corner (Figure 3). This indicates an improved overall quality, a greater intensity of the typical smell, and crispness (relative to PC1), and a lower position on the PC2 axis shows that products are greasier and the typical smell is reduced. Relative to the PC1 axis, the biscuits containing inulin were closer to 0 and positive values, whereas the ones with β-glucan tended to shift leftward. Therefore, this may indicate a positive impact of inulin on the overall quality, and on the desirable sensory characteristics of biscuits, such as typical taste and crispness.

Figure 3. Projection of scores and loadings on the PCA plot Q – overall quality.

Figura 3. Proyección de los resultados y cargas en el PCA gráfico Q – calidad total.

4. Conclusion

Replacement of shortening with oil led to a decline of sensory and physical properties of the biscuits. Adding inulin and lecithin to the recipes helped balance some of their properties to make products more similar to biscuits with shortening. The addition of lecithin had a positive impact on the quality of the products studied, primarily decreasing their hardness and increasing the volume. Fibers in products with a lower fat content had a reduced density compared with biscuits with oil and without fat replacers. β-glucan contributed to lowering the fat migration, although it negatively influenced the sensory quality of the biscuits. It was observed that lecithin addition reflected positively on the typical flavor and smell, crispness, hardness reduction and an improved overall quality. The biscuits containing inulin and lecithin and no fiber additives had results highly similar to the control sample with shortening. They differed in hardness regarding both sensory and mechanical properties. Therefore, further studies are needed to obtain oil-based biscuits with characteristics identical to products made with solid fat.

Disclosure statement

No potential conflict of interest was reported by the authors.