The development of gluten-free foodstuffs with high nutritional quality components is an important objective to achieve. Pachyrhizus ahipa is one of the few leguminous species that produce edible tuberous roots with high nutritional value. Thus, the aim of this work was to formulate biscuits containing corn starch and 125 - 350 g·kg -1 of P. ahipa flour (AF) and to study the main physicochemical properties related to their nutritional and technological quality as well as their sensory acceptability. The formulation containing 250 g of AF kg -1 was selected for improving the product nutritional quality (i.e. higher protein content) without an extensive modification of textural properties. A formulation replacing corn starch by cassava flour (250 g·kg -1) was also analyzed. In this case, ahipa and cassava biscuits showed maximum force and energy required to bite twice and three times higher than the control, respectively. Slight variations were observed in color (E and browning index). The overall acceptability of biscuits formulated with both flours was better scored than the control by a sensory panel. Principal component analysis allowed to relate quality attributes, chemical composition, and sensory characteristics of biscuits containing cassava or ahipa flours. The results indicated that ahipa flour could satisfactorily substitute part of the corn starch used in the formulations of gluten-free biscuits.
In quantitative terms, the gluten-free food market has shown a big grow in the last years, evidencing an annual rate of 28% [
People on a strict gluten-free diet are frequently undernourished since their rapidly available-energy intake, which in the western diet is largely taken from wheat-based foodstuffs, is reduced. This circumstance has prompted the development of gluten-free foodstuffs with high nutritional quality components [
On the other hand, in many tropical areas where wheat does not grow well, attempts are made to encourage the use of flours from locally grown crops which could totally or partially replace wheat flour for use in baked goods. This fact would contribute to decrease the demand for imported wheat and to obtain protein enriched products [
Pachyrhizus is one of the few genera of the leguminous family that produce edible tuberous roots with high nutritional value [
The objective of the present work was to formulate and elaborate biscuits containing Pachyrhizus ahipa flour and to study the main physicochemical properties related to their nutritional and technological quality as well as their sensory acceptability.
Ahipa flour was obtained by a slicing procedure [
Biscuits were cooked in an electrical static oven (Ariston FM87-FC, Italy) under natural convection. Different baking conditions were assayed: 180˚C-10 min; 200˚C-7.5 min; and 200˚C-10 min. The main quality attributes (water activity, color, and texture) were analyzed, evaluating the biscuit characteristics for selecting the appropriate baking condition. Once the percentage of substitution of ahipa flour was selected, the formulated product was compared to the control and with a formulation made with the same proportion of cassava flour, which was chosen as a reference ingredient frequently incorporated in gluten-free product formulations.
Water activity of the samples was measured at 25˚C with a Water Activity Meter Aqualab series 3 (Decagon Devices Inc., Washington, USA). A solution of saturated K2SO4 was used as a calibration standard (aw at 25˚C: 0.972). The average of three determinations, performed in two independent experimental batches, was informed.
Penetration tests were performed with a TAXT2i Texture Analyzer (Stable Micro Systems Ltd., Godalming, Surrey, UK). A 25 kg load cell was employed. The “Volodkevich Bite Jaws” probe was used in order to simulate the bite action of the incisive teeth on the sample. Parameters recorded were the maximum force (N) exerted when compressing 20% the sample, which is related to product firmness, and the area under the force curve (N mm) that is directly associated with the energy required in the process [
Surface color was measured using a Chroma Meter CR 400 (Konica Minolta Sensing Inc., Japan) calibrated with a standard white plate (Y = 93.2, x = 0.3133, y = 0.3192). Lightness (L*), red-green coordinate (a* value), and blue?yellow coordinate (b*) were registered. Color measurements were expressed as the total color difference (ΔE) calculated with respect to the coordinates (a0*, b0* y L0*) that characterized the color of the control baked cookies (C) (Equation (1)):
Likewise, the browning index (BI) [
The average of twelve determinations, performed in two independent experimental batches, was informed.
Total ash quantification (g∙kg−1) from dried samples (6 g) was performed gravimetrically after incineration in a muffle furnace (Indef 331, Córdoba, Argentina) at 550˚C. The liposoluble fraction (g∙kg−1 on a dry basis) was extracted with hexane from samples of grinded biscuits (12 g) in a Soxhlet apparatus. Likewise, baked biscuits (0.8 g) were analyzed for total nitrogen content by the Kjeldahl method [
A first sensory analysis was carried out using a semi-structured hedonic scale to evaluate the acceptability of the biscuits made with the selected percentage of substitution, cooked at different baking conditions (200˚C-7.5 min or 200˚C-10 min). A total of 60 potential consumers evaluated biscuit color, texture, taste and overall acceptability according to a box-scale (1 - 9) anchored in the following steps: “dislike very much”, “indifferent” and “like very much”. Samples were presented to the evaluators randomly arranged and coded with three digit numbers.
Once the baking time was selected, a second sensory analysis was carried out where the panelists were asked to evaluate color, texture, taste, and overall acceptability of control and the selected ahipa or cassava flour biscuit formulations.
The InfoStat Software (Version 2008) (InfoStat Group, Agricultural Sciences College, National University of Cordoba, Argentina) was used. Analysis of variance (ANOVA) and comparison of means with the Fisher’s least significant difference (LSD) test were conducted, at a significance level p = 0.05. The results were subjected to a Principal Components Analysis (PCA) and Cluster Analysis (CA) in order to observe the differences and similarities of the analyzed samples.
251 g of simple sugars kg−1 on dry basis [
Concerning texture measurements, the curves for the different biscuit formulations lacked a “defined” profile pattern in the sense that they were variable in shape and the remaining curves lost the initial penetration peak, except for the 200˚C-10 min cooking condition. McWatters et al. [
The textural parameters analyzed were the maximum force associated with the strength of the sample and the area under the curve, which represents the work done on the break (
When comparing maximum force at different baking conditions the values obtained
Ahipa flour content in the formulation (g∙kg−1) | Baking condition | |||||
---|---|---|---|---|---|---|
180˚C-10 min | 200˚C-7.5 min | 200˚C-10 min | ||||
Maximum force (N) | Area under the curve (N mm) | Maximum force (N) | Area under the curve (N mm) | Maximum force (N) | Area under the curve (N mm) | |
0 | 6.8 ± 0.5b | 15.6 ± 1.1a | 3.5 ± 0.7a | 8.8 ± 1.3a | 7.0 ± 1.4a | 7.5 ± 2.8a |
125 | 4.7 ± 0.5a | 18.9 ± 1.2b | 3.8 ± 0.9a | 15.7 ± 0.9b | 21.9 ± 1.6c | 31.0 ± 2.7c |
250 | 9.4 ± 1.8c | 30.6 ± 2.5c | 7.1 ± 0.6b | 28.3 ± 2.9c | 11.6 ± 1.6b | 19.9 ± 1.8b |
350 | 21.4 ± 1.8d | 54.2 ± 2.9d | 15.0 ± 1.0c | 58.7 ± 2.6d | 22.2 ± 1.3c | 40.0 ± 3.6d |
C: Control (1000 g∙kg−1 corn starch); 250AF: 250 g∙kg−1 ahipa flour + 750 g∙kg−1 corn starch; 250CF: 250 g∙kg−1 cassava flour + 750 g∙kg−1 corn starch. Reported values correspond to the mean ± standard deviation. Data followed with the same letter within a column did not differ significantly (p > 0.05).
for the 350AF formulation were 3.15, 3.2 and 4.3 times higher than the control for 180˚C-10 min, 200˚C-10 min and 200˚C-7.5 min, respectively. Conversely, for the 250AF formulation, maximum force was 1.38, 1.65 and 2.0 times higher than the control, for the same baking conditions respectively (
Demirkesen [
Considering that the inclusion of ahipa flour could improve the nutritional profile of the product on the basis of its higher protein and fiber content, the formulation 350AF might make the major contribution in this sense. However, textural measurements for this formulation revealed that hardness was significantly higher than the controls, added to the highest ΔE. Thus, the formulation 250AF was selected and characterized.
Owing to color and texture measurements (
Ahipa flour content in the formulation (g∙kg−1) | Baking condition | ||||||
---|---|---|---|---|---|---|---|
180˚C-10 min | 200˚C-7.5 min | 200˚C-10 min | |||||
Water activity (aw) | Moisture content (g∙kg−1) | Water activity (aw) | Moisture content (g∙kg−1) | Water activity (aw) | Moisture content (g∙kg−1) | ||
0 | 0.448 ± 0.001b | 86.0 ± 2.6b | 0.620 ± 0.005d | 101.0 ± 3.0b | 0.380 ± 0.002c | 73.2 ± 4.2b | |
125 | 0.538 ± 0.006c | 108.6 ± 1.5c | 0.568 ± 0.002c | 106.3 ± 0.7c | 0.400 ± 0.002d | 88.4 ± 0.8c | |
250 | 0.458 ± 0.003b | 76.0 ± 2.6a | 0.516 ± 0.001b | 84.0 ± 2.9a | 0.340 ± 0.07b | 62.2 ± 4.5a | |
350 | 0.391 ± 0.005a | 90.4 ± 3.8b | 0.505 ± 0.001a | 109.4 ± 1.1d | 0.304 ± 0.006a | 77.2 ± 1.9b | |
C: Control (1000 g∙kg−1 corn starch); 250AF: 250 g∙kg−1 ahipa flour + 750 g∙kg−1 corn starch; 250CF: 250 g∙kg−1 cassava flour + 750 g∙kg−1 corn starch. Reported values correspond to the mean ± standard deviation. Data followed with the same letter within a column did not differ significantly (p > 0.05).
values from the hedonic scale were grouped in three ranges: 1 - 3 (dislike); 4 - 6 (not like nor dislike, i.e. indifferent); and 7 - 9 (like very much).
Chemical composition of the biscuits formulated with 1000 g corn starch kg−1, and partially substituted (250 g∙kg−1) with ahipa or cassava flour was evaluated (
Total lipids found in the biscuits were similar and no significant differences (p > 0.05) were observed (
Biscuits made with ahipa flour exhibited the highest protein content, due to the chemical composition of the flour [
Likewise, the total dietary fiber content in AF-biscuits was the highest (50 g∙kg−1), because ahipa flour can be considered as a fiber source [
Biscuit formulation | Texture parameters | Color parameters | Water activity (aw) | Moisture content (g∙kg−1) | Chemical composition (g∙kg−1) | |||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Force (N) | Area (N mm) | Force peak number | Color differences (ΔE) | Browning index (BI) | Proteins | Lipids | Ash | Total dietary fiber | Carbohydrates | |||
C | 3.5 ± 0.7a* | 8.8 ± 1.3a* | 26.3 ± 5.0b | 0.0 ± 0.0a* | 21.1 ± 1.5a | 0.620 ± 0.005c* | 101 ± 3b* | 13 ± 1a | 172 ± 10a | 6.7 ± 0.4a | 19 ± 8a | 810 ± 20a |
250AF | 7.1 ± 0.6b* | 28.3 ± 2.9b* | 12.8 ± 3.9a | 14.8 ± 0.9c* | 36.2 ± 2.2c | 0.516 ± 0.001a* | 84 ± 3a* | 26 ± 1b | 172 ± 5a | 8.4 ± 0.2b | 50 ± 14b | 793 ± 8a |
250CF | 7.2 ± 0.6b | 27.1 ± 2.3b | 12.8 ± 3.6a | 12.0 ± 0.8b | 30.7 ± 0.7b | 0.547 ± 0.002b | 85.3 ± 0.5a | 15.7 ± 0.1a | 182 ± 5a | 7.7 ± 0.1b | 32 ± 1a | 795 ± 7a |
C: Control (1000 g∙kg−1 corn starch); 250AF: 250 g∙kg−1 ahipa flour + 750 g∙kg−1 corn starch; 250CF: 250 g∙kg−1 cassava flour + 750 g∙kg−1 corn starch. *From
Concerning biscuit texture, the maximum force registered for the 250AF biscuits was higher (1.4 - 2.0 times) than the control. Formulations including ahipa or cassava flour showed the same texture behavior, with regard to maximum force, area under the curve and crunchiness (
Regarding color measurements, partially substituted formulations differed significantly from the control. Although statistically significant (p < 0.05), slight differences between cassava and ahipa flour formulation were found in terms of total color difference (ΔE) and browning index (BI) (
Both moisture content and aw were higher for control biscuits (
Complementing chemical and physical analysis, results from the sensory tests performed in order to evaluate the acceptability of the developed product (250AF) in comparison to the control biscuits and the same percentage of substitution with cassava flour (250CF) are shown in
For the attribute taste, the most accepted formulation was the one made with 1000 g of corn starch kg−1 (
Overall acceptability of the biscuits in the sensory panel was evaluated as good, given that the predominant score was 7 for this attribute (
The results of quality attributes, chemical composition, and sensory characteristics were subjected to multivariate analysis by Principal Component Analysis (PCA) and Cluster Analysis (CA). In these analyses, the following variables: protein and fiber content, browning index, water activity, force, overall acceptability and sensorial attributes (color, texture and taste), which allowed to discriminate the samples, were considered.
There were two main components that explained the total variance (
Cluster Analysis was performed, using the uncorrelated variables that represent data obtained in the principal component analysis.
The formulation containing 250 g of AF kg−1 was selected in order to improve the nutritional profile of the product on the basis of its higher protein (26 g∙kg−1) and fiber (50 g∙kg−1) content. It is worth noting that gluten-free products derived exclusively from cassava flour have relatively low protein and fiber levels.
Sensory tests ultimately defined baking condition, being 200˚C-7.5 min chosen as the most widely accepted by the evaluation panel. This time-temperature combination re- presents also an advantage from the operative point of view, since it allows to an energy and cooking time saving.
Comparing the novel ahipa biscuit formulation to a cassava flour equivalent recipe (a common ingredient for gluten-free products elaboration), its performance was similar in terms of textural characteristics (maximum force, energy required to bite and force peak number). However, slight variations were observed in color total differences and browning index. Likewise, the overall acceptability of the biscuits formulated with AF and CF exhibited better sensory general acceptability than the control, since the predominant score was 7 for this attribute.
Principal components analysis allowed to relate quality attributes, chemical composition and sensory characteristics of biscuits containing cassava or ahipa flours. Cluster analysis indicated that biscuits formulated with 250 g∙kg−1 of nutritionally differentiated root flours (cassava or ahipa) were similar between them and this statistical inference has also been mirrored by the panelists.
New interest in under-utilized crops and their derived products (i.e. flours, starches, protein concentrates and isolates) arises largely from the finding and endorsement of nutritionally significant attributes. These products can also increase their value as functional foods and ingredients. On the basis of the results from the present work, ahipa flour could partially substitute corn starch in future formulations for the production of gluten-free foodstuffs, allowing getting nutritionally balanced products and good consumer acceptance.
Financial support provided by the ANPCyT (PICT 2011-1213) and CONICET (PIP 0555) is gratefully acknowledged. Authors wish to thank to Fassola Hugo, Rohatsch Pablo and Feltan Rafael, from the EEA Montecarlo (INTA, Misiones), for ahipa and cassava root provision.
Doporto, M.C., Sacco, F., Viña, S.Z. and García, M.A. (2017) Quality and Technological Properties of Gluten-Free Biscuits Made with Pachy- rhizus ahipa Flour as a Novel Ingredient. Food and Nutrition Sciences, 8, 70-83. http://dx.doi.org/10.4236/fns.2017.81005