functionality and organoleptic properties of maize tortillas enriched with 1 five...

8/19/2019 Functionality and Organoleptic Properties of Maize Tortillas Enriched with 1 Five Differentnandez2015

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ABSTRACT

Soybean proteins are ideally suited to enhance the essential amino acid balance of cereal-based

foods. The aim of this investigation was to assess the functionality of different soybean proteins

in maize tortillas using yield, sensorial and textural shelf-life characteristics as criteria to select

the best supplement. Four different defatted soybean flours (SBF1, SBF2, SBF3, and SBF4) and

one soybean protein concentrate (SBC) were added to increase protein content of dry masa flour

between 25 to 30%. The evaluated soybean ingredients depicted Urease Activity between 0.1 to

2.25, Water Absorption Index of 4.02 to 8.34, Protein Dispersability Index of 23 to 75% and Fat

Absorption Index ranging from 2.5 to 3.1. Moisture, crude protein, crude fat and rollability were

not different among produced tortillas, but maximum force after five days of storage was higher

for SBF1 and lower for SBF 3. Control and SBF1 followed by SBC were the best overall

evaluated supplements according to the most relevant parameters for consumers and producers.

Correlation analyses depicted a negative association among yield-related parameters and Protein

Dispersability Index, Urease Activity and Water Solubility, opposite to relationship for texture-

related properties. The best soybean proteins to be used in maize tortilla supplementation should

have, preferably, reduced Water Solubility, Urease Activity and Protein Dispersability Index.

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a p e r h a s b e e n p e e r r e v i e w

e d a n d a c c e p t e d f o r p u b l i c a t i o n b u t h a s n o t y e t b e e n c o p y e d i t e d o r p r o o f r e a d .

T h e f i n a l p u b l i s h e d v e r s i o n m a y d i f f e r .


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INTRODUCTION

Protein malnutrition is still an endemic problem in many developing countries around the globe.

It is known to inhibit growth and have a profound and significant effect on physical

development, susceptibility to infectious diseases and brain maturity. An early malnutrition

reduces both the brain and cerebellum sizes (Chase et al 1967; Culley and Lineberger 1968), the

number of neurons and synapsis (Stylianopoulos et al 2002; Warren and Bedi 1984) and the

neuron myelization process mainly due to the lower synthesis of proteolipids, cerebrosides,

sulphatides and plasmalogen of the white substance. Functionally speaking, this reduction is

relevant because myelinized axons transmit information faster than non-myelinized fibers

(Wiggins 1982). Post-mortem inspection of children that were severely affected by Marasmus

found significantly lower levels of brain cholesterol, phospholipids, RNA and DNA (Rosso et al

1970).

Mexico has one of the highest world per capita consumption of maize ( Zea mays L) and the main

food product from this cereal is tortilla. The lower the socioeconomic status, the greater the

dependence on tortillas. Unfortunately, tortillas are not a perfect food because they lack of two

essential amino acids, lysine and tryptophan, and adequate levels of iron, zinc and vitamins A, D,

E and B12. That is the reason why tortillas are ideally suited for nutritional enrichment and

protein fortification (Amaya-Guerra et al 2004, 2006; Serna-Saldívar et al 1988; Stylianopoulos

et al 2002).

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a p e r h a s b e e n p e e r r e v i e w e d a n d a c c e p t e d f o r p u b l i c a t i o n b u t h a s n o t y e t b e e n c o p y e d i t e d o r p r o o f r e a d .



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tonnes. Soybeans are mainly channeled to the oil crushing industries in order to extract the oil

and the defatted soybean meal. The full-fat, defatted, concentrates and isolates contain about 42,

49, 65 and 90% protein, respectively. These products are widely applied in the food industry as

important ingredients due to their highly nutritious and desirable functional properties. However,

in many cases, the application of these types of proteins is limited due to incompatibility between

their solubility and other properties (Wang et al 2008). The enhancement of protein quality and

nutritional value of soybean-fortified maize tortillas was first documented with laboratory

animals in the 1970´s (Bressani et al 1974; Bressani et al 1979; Del Valle and Perez-Villaseñor

1974). These early investigations clearly indicated that it was feasible to produce fortified

tortillas with enhanced protein quality. Amaya-Guerra et al (2004, 2006) determined the

physiological development and brain development of rats fed with soybean fortified tortilla-

based diets for two generations. Growth, reproductive performance, brain development and short

and long term memory of rats fed with soybean fortified tortillas were significantly higher than

counterparts fed with regular tortillas. Chavez and Chavez (2004) conducted a two year blind

study with humans that evaluated the effect of soybean fortification and enrichment with selected

micronutrients of dry masa flours in two neighbor rural communities located in México. Infants

and children who received the soybean fortified masa flour grew 49% more than counterparts fed

with regular diet. Clinical tests showed that subjects consuming the fortified/enriched tortillas

improved their hair, nails and skin conditions. Pregnant women that consumed fortified tortillas

gave birth to newborns with significantly higher weights and only 3% of the babies had lower

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adopted this technology because the soybean flour affects the organoleptic properties. To our

knowledge there are not investigations aimed to compare functional properties of soybean

proteins in the maize tortilla system. Therefore, the aim of this research was to evaluate the

functionality of five different commercial types of soybean proteins in maize tortillas. The yield

and physical, chemical, sensorial and textural shelf-life during storage at room temperature were

used as the criteria to select the best soybean protein.

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MATERIALS AND METHODS

Maize and soybean flour samples

Composite flours were obtained by mixing commercial nixtamalized maize flour (Control

treatment, Maseca Premium Plus, high yield dry masa flour supplied with gums and emulsifiers)

with about 6% (6 g per each 100 g of nixtamalized maize flour) of four different defatted

soybean flours (Industrial de Alimentos, SBF1; GAF 120, SBF2; ADM, SBF3 and Ragasa,

SBF4) or 4% (4 g per each 100 g of nixtamalized maize flour) soybean concentrate (Nutrigrains

Industries, SBC). The percent soybean flour/concentrate added was fixed at the above levels so

as to obtain 25-30% higher protein content in the composite flour'. In order to produce the

dough or masa, one part of the dry masa flour was hydrated with about 1.3 parts water (water

was adjusted after a pre-evaluation of the hydration performance of the composite flours). The

level of protein enrichment allowed an increase in essential amino acid content in at least 30%

compared with the control treatment.

Rheological, chemical and functional characterization of flour.

The viscoamylograph properties of the control and soybean enriched dry masa flours were

evaluated with the Rapid Visco Analyzer (RVA, StarchMaster2, Perten Instruments) according

to Fernández-Muñoz et al (2011). The soybean products were characterized for moisture (44-

15A -AACC, 2000-), crude protein (AACC 46-13 -AACC, 2000-), pH and electrical

d i i (B hT M HI 2550 H I ) F A i Ni (FAN

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T h e f i n a l p u b l i s h e d v

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Solubility Index (NSI), and percentage coagulation at high temperature were determined

according to Cheftel et al (1989). Foam Capacity (FC) was calculated as recommended by

Haque and Kito (1983). The complete amino acid profile was obtained following the AOAC

Official Method 982.30 (AOAC 1980).

Tortilla production at pilot plant facility

Composite flours were blended with tap water which was added based in subjective evaluations

of the handling properties of the resulting dough or masa. 1 kg of regular or composite flours was

blended with 1.15 to 1.45 L of water for 3.5 min in a Hobart mixer (5L N-50 Planetary Mixer)

equipped with a hook attachment. The resulting masa was sheeted and formed into 30 g tortilla

circles and continuously baked in a three-tier baking oven for 68 seconds (Manufacturas C&D

Industriales, Monterrey, NL, Mexico). The average weight of tortillas obtained was 27 grams

and the surface temperature of each stage at the oven was set to 230, 270 and 250°C. Once the

water absorption was tuned for each experimental flour, trials were performed in 2 kg batches.

The baked tortillas were allowed to cool down on a counter for 30 min at room temperature

(25±2°C) and immediately packaged in polyethylene bags at room temperature for textural,

color, sensorial and chemical evaluations.

Chemical and sensory properties of maize tortillas

Tortilla moisture was determined using the oven method (44-15A, -AACC, 2000), crude protein

i h h i Kj ld hl d (46 30 AACC 2000) d d f f h i

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Tortilla quality during storage

Tortillas were stored at room temperature and at day 0, 1, 2 and 5 each treatment was evaluated

for luminosity, texture and rollability. Color was obtained using a colorimeter (CR 300, Minolta,

Osaka Japan) at least in three samples and three different spots of the same sample. Lighting

conditions used for color test were the same (performed under the same lamp and at the same

distance). Texture changes were determined as the maximum force required for penetration using

a cylindrical probe attached to a Texturometer (TA XT 2i, Stable Micro System) whereas

rollability was subjectively rated by rolling tortillas around a 1 cm wooden dowel. The rating

scale employed was 1 (no cracks; very flexible) to 5 (break immediately; cannot be rolled)

(Serna-Saldívar 2012).

Integral evaluation of studied parameters

In order to perform an overall assessment of the maize tortillas obtained with flour enriched with

soybean products, an evaluation with the key parameters for producers and consumers (color,

texture and sensorial components as well as process yield) was completed. For each parameter, a

percentage of the total score was assigned using an empirical approach (experience in

nixtamalized maize tortilla production and consumption). Briefly: yield is a trait very important

to tortilla producers (30/100 weight) as well as sensorial characteristics (30/100). The latter in

turn are of paramount importance for consumers, as well as all texture-related traits (rollability

and texture 30/100 both). Luminosity is also a very important tortilla characteristic, mainly for

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b u t h a s n o t y e t b e e n c o p y e d i t e d o

r p r o o f r e a d .




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basis). Once the evaluation frame was set, values from 1 to 6 were assigned to each treatment

according to statistical differences obtained after the different analyses. One was the best and 6

the worst grade. An overall score was estimated, being the highest value the worst assessment

from consumers and producers viewpoints.

Statistical analysis

Chemical, functional, textural properties of flours as well as process yield for each triplicated

treatment were analyzed with ANOVA (Analysis of Variance) procedures. Differences among

means were calculated with Tukey’s tests (alpha=0.05). Correlation analysis was made with

triplicate results for the five samples used for protein enrichment. The statistical software used

was Statistix (v.9).

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a p e r h a s b e e n p e e r r e v i e

w e d a n d a c c e p t e d f o r p u b l i c a t i o n





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RESULTS AND DISCUSSION

Chemical, rheological and functional properties of composited flours

Differences among chemical and functional properties of soybean products are depicted in Table

I. pH values ranged from 6.6 to 6.8 for all defatted soybean flours and the concentrate. Moisture

was also similar, except for SBF 3 which contained 14.3%. The lowest and highest protein

contents of 42.4 and 67.1% were for the SBF1 and the SBC, respectively. The last could be then

classified as a concentrate because it contained a protein higher than 65 and lower than 70%. The

rest of the soybean products are categorized as defatted meals obtained after desolventization in a

desolventizer-toaster (DT; Mustakas 1971; Riaz 2006).

Urease activity values differed among the soybean protein sources. This assay is related to the

protein denaturation due to heat treatments applied during the process. SBF1 and SBF2 had

values below 0.2 whereas SBF3 and SBF4 values higher than 2.0 indicating that the first group

received more heat during processing. The urease activity is closely related to PDI so SBF 3 and

4 had the highest PDI values indicating an insufficient heating or diminished protein

denaturation. According with Smith (1977), urease activity of 0.3 or less suggests that the

product (despites a slight urease activity) has received an adequate heat treatment for the

deactivation of antinutritional factors. Different PDI materials were purposely tested because

their less denatured proteins have different functionalities especially during masa formation and

assuming that the inhibitors were destroyed during the subsequent tortilla baking step.

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regularly has PDI values of 90, followed by defatted soy flour with 70. On the other hand,

enzyme inactive soy flours, regularly have PDI values of 20 to 30 (Riaz 2006). High PDI

ingredients are more soluble, because the thermal treatment alters the hydrophilicity /

hydrophobicity ratio of the protein surface (Riaz 2006). High solubility in soybean protein is a

desirable trait, because of the required mixing of the ingredients with water. Furthermore, soluble

proteins are easier to incorporate in food systems (Jideani 2011). Water solubility (WS) as the

percentage of solids solubilized in water (under standard conditions) compared to the total initial

amount of the evaluated sample, were 25.7, 28.4, 50.3, 47.6 and 37.0 for SBF1, SBF2, SBF3,

SBF4 and SBC respectively, results consistent with PDI values. According to Jideani (2011)

defatting increases protein solubility, being this property also influenced by the hydrophilicity /

hydrophobicity balance which in turn depends on amino acid composition (Moure et al 2006).

Other functional property related with hydration is water absorption index (WAI), which can be

described as the ability of the meal to retain water against gravity. According to Moure et al

(2006), the retained water includes: bound, hydrodynamic, capillary and physically entrapped

and mainly depends on the amino acid composition and exposure of amino acid residues. WAI

improves with the number of charged amino acid residues (Kuntz and Kauzmann 1974).

Electrical conductivity (data not showed) was higher for SBC (3.6 ±0.12 mS/cm) compared with

the rest of the soy products (2.0±0.0 to 2.6±0.0 mS/cm) indicating differences in the

concentration of ions and electrical conductive particles and in some degree to the capacity of the

material to absorb water WAI for the array of soy products (Table I) indicated that the highest

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absorption. This could be the reason why SBF1 and SBF2, with a high thermal treatment

(depicted by their low PDI value), were comparatively rated with higher WAI.

Regarding FAN, the highest values were associated to SBF3, SBF4 and SBC (Table I). FAN

determines the nitrogen readily available for microorganisms and chemical reactions and gives

an indication of degree of protein hydrolysis. Porter and Jones (2003) determined FAN for 22

soybean flours obtaining an average of 1.22 ± 0.11 mg/g. This mean value was similar to the

observed in SBF3 and SBF4 that received a mild heat treatment during processing (after

industrial oil extraction). According to Porter and Jones (2003), FAN concentration varies with

the soybean used for flour production and maturity of seeds at harvest and moisture of beans in

the different stages of production and storage.

One of the most important parameters within this evaluation was indeed the protein amino acid

profile of the composite flour used for tortilla production (Table II). As planned, addition of

approximately 6% soybean flours and 4% SBC increased 25 to 30% the protein content. All

cereal-based products had lysine as the most limiting amino acid followed by tryptophan. On the

other hand, all composite flours and tortillas have adequate amounts of sulfur containing amino

acids due to the high levels of maize proteins known to have excess levels of these amino acids

(Table II). Regarding lysine, maize contains around 2.0 to 2.5 g of this amino acid per 100 g

protein. With the addition of SBF 1 to 4 and SBC, lysine content increased 56 to 95% (Table II).

The essential amino acid profile of the enriched tortilla flours was thus greatly improved due to

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treatments, as previously described, lysine was the limiting amino acid followed by tryptophan.

All other essential amino acids exceeded the requirements of protein for a 2 to 5 year-old infant

according to FAO and WHO recommendations (WHO, 2007). In the specific case of lysine,

control met the 50% of the daily requirement, whereas soybean enriched treatments between

67.8 to 69.1%. This important improvement in protein quality greatly improves protein

digestibility corrected essential amino acid scores, nitrogen retention and growth of both

experimental animals and humans (Amaya-Guerra et al 2004, 2006; Bressani et al 1974, 1979,

Bressani 2008; Chavez and Chavez 2004; Del Valle and Perez Villaseñor 1974; Serna-Saldívar

and Amaya-Guerra 2008).

Similar results were reported with other protein enrichment protocols and the direct addition of

essential and limiting amino acids. For example, Lecuona-Villanueva et al (2012) developed an

enriched nixtamalized flour by directly adding 0.2% lysine and 0.03% tryptophan yielding

similar levels to the obtained in this research. This type of fortification has been widely studied

because of the amino acid balance and the influence of this factor in animal and human growth,

nevertheless, the use of soybean protein is ideally suited to counteract deficiencies because it

contains at least 15 times more lysine and tryptophan compared to maize and other cereals.

Besides, soybean products are generally sold at low cost and have high market availability.

The typical viscoamylograph curves of the control and enriched masa flours are depicted in Fig.

1. According to Almeida-Dominguez et al (1996) the viscoamylograph behavior is an effective

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enriched with the SBC. The soy concentrate depicted a different behavior compared with the rest

of treatments because the composite flour needed a higher pasting time and lower pasting

temperature and peak and set back viscosities. The pasting temperature is related to the energy

required to cook the sample indicating that the SBC somehow interfered with the starch

gelatinization phenomena. Other interesting difference is that the flour enriched with SBC had

more stability to prolonged thermic process (95°C), because of the steady viscosity observed

during this stage of the assay.

Peak viscosity, an indicator of the water-binding capacity (Perten 2011) of starch granules, was

lower for the flour enriched with the SBC (Fig. 1). Interestingly, the SBC had the highest water

absorption index among all the evaluated soybean materials (8.34 versus an average of 4.8 for all

the defatted soybean flours).

One parameter also useful in food processing is the holding strength of the evaluated material or

hot paste viscosity. This indicates the ability of the sample to withstand the heat and shear stress.

All samples depicted a similar shear thinning except for flours containing SBF1 and SBC, which

performed better due to the lower viscosity decrease during the heat holding period of the assay.

All enriched flours depicted a similar set back viscosity, rheological parameter related to

synaeresis of starch upon cooling of the cooked starchy material (Sandhu and Singh 2007) and

thus to the rate of starch retrogradation and loss of tortilla texture during storage (Fig. 1). The

highest and lowest final viscosities were observed for flours containing SBF1 and SBC,

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In Table III, results of chemical composition and textural characteristics of maize tortillas are

depicted. All tortillas contained moistures between 37.4 to 50.5% related to the water adjustment

made during the masa forming process. Interestingly, the SBF 3 and 4 enriched tortillas

contained lower moisture compared to the rest of the treatments likely due to their high PDI

values. The flour enriched with SBF1 and SBF2 produced tortillas that with practically the same

moisture compared to the control tortillas. Bressani (2008) reported an average tortilla moisture

content of 47.8%, similar to SBF1, SBF2, SBC and control (Table III).

As expected, all soybean enriched tortillas contained higher protein compared to the control. The

protein content for the enriched tortillas ranged from 11 to 14% compared to 9.17% observed in

control tortillas. The tortillas enriched with SBF4 and SBF2 contained slightly higher protein

content compared to the rest of the enriched counterparts. According to Bressani (2008) the

average protein expressed on dry basis for white and yellow tortillas was 10.3 and 10.6%

respectively. According to Serna-Saldívar and Amaya-Guerra (2008), the protein quality of raw

corn and its tortillas is considered low, because of the deficiencies on lysine and tryptophan.

One parameter used for texture and quality assessment during storage is rollability and bending

tests (Serna-Saldívar 2012). These assays detect changes in tortilla texture throughout storage,

being the latter an objective measurement that can be correlated with subjective information

obtained from rollability and flexibility test scores. Suhendro et al (1998) devised a tortilla

bending technique and a rollability test sensitive to changes in texture. Maximum forces required

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penetration force (8.95 N) whereas the SBF3 and SBC tortillas the softest with only 5.9 and 6.8

N, respectively (Fig. 2). Interestingly, these tortillas were produced with the high PDI soybean

flours. Thus, the low heat treated soybean flours favored the texture of stored tortillas.

Texture and color during storage of control and soybean-enriched tortillas.

The different tortilla systems had dissimilar changes in color and texture during storage. In

terms of color, the luminosity or L values dropped due to addition of soybean products (Fig. 3).

The tortilla enriched with SBF4 which had the highest FAN showed the lowest luminosity

whereas the rest of the fortified tortillas had similar values compared to the control. All tortillas,

except the ones enriched with SBF4, gradually decreased L values during storage. The rate of L

value loss was similar among treatments. Green et al (1977) described changes in color of

fortified tortillas when full-fat soy flour was used above 12%. Figueroa et al (2001) observed

that with only 4% of defatted soy flour in tortilla (+ vitamin addition) yielded a product with

different color compared to the control.

In terms of tortilla texture, the maximum force changed from day 0 to the fifth day of storage at

room temperature (Fig. 2). All fresh tortillas (day 0) had an average penetration force of

4.48±0.51 N and 7.58±1.12 N at the end of storage (day 5). Tortillas enriched with SBF3 were

softer or required less penetration force (5.93 N) compared to counterparts enriched with SBF1

(8.95 N). These results clearly indicate that tortillas lose texture during storage due to starch

retrogradation and that addition of various soybean sources affected differently the texture of


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In Fig. 4 results for sensory evaluation of tortillas are displayed. Five parameters were evaluated:

color, taste, odor, texture, as well as general tortilla acceptance. The highest the value, the lowest

acceptability. Regarding color, all enriched tortillas were evaluated better than the control. SBF4,

the treatment with lower luminosity (Fig. 3) was one of the best evaluated by the panelists. SBF1

was one of the best with respect to taste and SBF2 regarding odor. The last two materials (SBF1

and SBF2) were also the lower in PDI and urease activity values (Table I). SBF3 tortillas scored

low in terms of taste, odor and overall acceptability, being this soy enriched tortilla similar to

SBF4 in terms of chemical and functional properties (Table I).

Changes in tortilla yield due to the addition of the various types of soybean proteins.

Tortilla yield is depicted in Fig. 5. The best treatments were the control and the SBF1 enriched

tortilla followed by tortillas enriched with SBC5, SBF2, SBF3 and SBF4, respectively. It is

important to mention that the control commercial flour is a high yielding due to its low moisture

content and supplementation with hydrocolloids and emulsifiers. These results indicate that the

SBF4 (high PDI) was unable to retain as much water during masa mixing and tortilla baking

operations compared with other sources as SBF1 and SBF2 with reduced PDI. Addition of high

PDI soybean flours SBF3 and SBF4 significantly reduced tortilla yields compared to the control

and SBF1 enriched counterparts.

Overall evaluation of five different soybean proteins used in nixtamalized maize

tortillas production.

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percentages of the total score (100%), were assigned to each factor according to the relative

importance of each one from the consumers and producers viewpoints. In this evaluation, the

lowest the overall score, the highest the desirability of the tortilla system. The control and SBF1

enriched tortillas were the best overall evaluated products. Thus, the SBF1 with a PDI of 23.17%

yielded higher amounts of enhanced protein quality tortillas. These tortillas had similar sensory

properties, texture throughout storage and color compared to the control.

Correlation among the physicochemical characteristics of soy products and the most

important tortilla parameters

In order to further analyze the role and functionality of soy-products within a nixtamalized

tortilla production system, a correlation assessment was performed and the coefficients are

summarized in Table V. The most significant relationships were between yield-related

parameters (tortilla and masa moisture) and PDI, urease activity and WS. These connections

resulted negative and highly significant. The lower the PDI, Urease Activity and WS, the higher

tortilla final yield. A similar correlation was found among acceptability and thermic treatment

associated parameters as WS. The lower the WS, the better the general acceptability.

Different to yield and acceptability, textural related parameters as rollability and texture force

were positively correlated with PDI and WS. The higher the PDI and WS, the best tortillas in

terms of textural properties during storage. Regarding texture, mild treatments in soy products

are convenient for their use as supplements for tortillas. In terms of texture, the best rated soy

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CONCLUSIONS

Functional properties of five different soybean commercial products (SBF1 to SBF4 and SBC)

within maize tortilla system were fully evaluated in terms of texture, color, sensorial

acceptability and nutrimental profile, the most important parameters for producers and

consumers of this Latin-American traditional food. Tortillas were enriched with 3% of protein

weight from the assessed soybean ingredients in order to increase between 25 to 30% protein

content in dry masa flour, yielding composite flours with an upgraded essential amino acid

profile (double lysine and tryptophan) compared to the 100% nixtamalized maize counterpart.

These flours depicted differences in viscoamylographic properties compared to the control

(lower viscosity and setback for SBC). Soybean ingredients were characterized and two of them

showed high UA and PDI, whereas a third one had a relatively protein concentration compared

with soybean flours (>60%). Tortillas produced using this enrichment strategy depicted similar

chemical properties, differences in color and slightly differences in the texture after five days of

storage. The best tortillas in terms of texture (texturometer and rollability) were the produced

with SBF3 and SBF4 (materials with high UA and PDI) but were the worst in yield evaluation.

The SBF4 was the poorest in luminosity evaluation. Interestingly these differences were not

detected by the sensorial evaluation panel. Correlation analysis depicted a significant negative

association between yield-related parameters (tortilla and masa moisture) and PDI, urease

activity and WS. Regarding texture, mild heat treated soy products are convenient for their use as

tortillas supplements After an integral assessment tortillas produced with SBF1 were the best


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ACKNOWLEDGMENTS

The authors would like to acknowledge USSEC for providing the array of soybean samples and

sponsoring this research.

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i s t r y J o u r n a l " F i r s t L o o k " p a p e r •

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TABLES

Table I. Chemical and functional properties of the soybean products used to enrich maize

tortillasa

Soy

Product

Chemical Functional

pH

Moisture

(%)

Protein

(%, db)

Urease

Activity

FAN

(mg/g)

Reducing

sugars

(mg/g)

Water

Absorptio

n Index

(WAI)

PDI

(%)

Fat

Absorption

Index

(FAI)

SBF 1 6.67±0.007 b 8.28±0.11b 42.4±0.17 e 0.10 ± 0.01e 0.62±0.01 d 81.0±0.40 c 5.38±0.02b 23.17 ± 0.11 d 2.5 ± 0.02 d

SBF 2 6.63±0.000 bc 7.93±0.16b 49.6±1.90 c 0.15 ± 0.01 d 0.59±0.01 d 5.0±0.40 d 4.8±0.25c 25.34 ± 1.55 d 2.94 ± 0.03 b

SBF 3 6.48±0.026d 14.25±0.8a 58.6±0.44b 2.25 ± 0.01a 1.23± 0.02 c 88.0±0.70 a 4.02±0.03d 75.45 ± 1.62 a 2.65 ± 0.05 c

SBF 4 6.78±0.023a 3.58±0.07c 45.4±0.10 d 2.20 ± 0.03 b 1.40± 0.03 b 85.0±0.7 b 4.29±0.07d 66.96 ± 1.51 b 3.14 ± 0.03 a

SBC 6.56±0.057 c 4.11±0.03c 67.1±0.20 a 0.40 ± 0.01 c 1.87±0.04 a 7.0±0.40 d 8.34±0.08a 52.03 ± 0.45 c 2.7 ± 0.09 c

a Data in the table are the average of at least three replicas ± standard deviation. Means with different letter(s) within columns are

statistically different (P < 0.05).

C e r e a l C h e m


h t t p : / / d x . d o i . o r g / 1 0 . 1

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Table II. Essential amino acid content for the mixes used for tortilla production

Essential Amino Acid

Amino acid (g/100g protein)

Control

Flour Enriched with

SBF1 SBF2 SBF3 SBF4 SBC

Threonine 3.62 3.81 3.81 3.82 3.82 3.74

Valine 4.83 4.97 4.95 4.94 4.98 4.93

Methionine + Cysteine 3.98 2.97 2.97 2.97 2.97 2.97

Isoleucine 3.62 4.01 4.00 3.97 4.02 3.99

Leucine 13.03 11.94 11.94 11.89 11.93 11.94

Phenylalanine+Tyrosine 7.60 5.67 5.67 5.67 5.67 5.67

Lysine 2.90 3.93 3.94 3.97 4.01 3.94

Histidine 2.90 2.89 2.89 2.88 2.90 2.90

Tryptophan 0.72 0.98 0.99 0.96 0.94 0.93

Amino acid scorea 49.9 67.8 68.0 68.4 69.1 68.0

a Limiting amino acid was lysine for all treatments considering a requirement for infants of 5.8 g lysine/100 g protein.

C e r e a l C h e m


h t t p : / / d x . d o i . o r g / 1 0 . 1

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Table III. Chemical composition and textural characteristics of nixtamalized maize tortillas

enriched with different soy productsa.

a Data in the table are the average of at least three replicas ± standard deviation. Means with different letter(s) within columns are

statistically different (P < 0.05).

b Crude protein (nitrogen x 6.25) and fat values are expressed on dry matter basis.

c Subjective scale from 1 to 5, where 1 indicates an excellent rollability and 5 a poor performance during this test.

Tortilla sample Moisture (%)

Crude

Proteinb (%)

Crude Fatb

(%)

Cold

rollability

at five days

of storage

c

Maximum force

at five days of

storage

(Newtons, N)

Control 50.5±1.4 a 9.17± 0.45 c 3.71±0.01 a 2.7±0.14 a 8.23±0.22 ab

SBF 1 48.6±0.9 ab 11.52±0.01 bc 4.82±0.10 a 3.6±0.07 a 8.95±0.17 a

SBF 2 48.3±0.4 ab 13.10±1.09 ab 5.07±1.32 a 3.4±0.28 a 8.36±1.02 ab

SBF 3 37.4±1.3 c 10.71±0.31 bc 1.24±0.12 b 3.0±1.84 a 5.93±1.07 b

SBF 4 37.6±1.4 c 14.22±0.96 a 1.15±0.15 b 2.2±1.41 a 7.15±0.47 ab

SBC 45.6±0.3 b 10.73±1.70 bc 1.53±0.06 b 3.3±0.49 a 6.84±0.65 ab

C e r e a l C h e m


h t t p : / / d x . d o i . o r g / 1 0 . 1

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Table IV. Nixtamalized maize tortillas overall evaluationa

Treatment

Parameter

Overall

ScoreRollability Luminosity

Sensory

Evaluation

Yield

Texture

(maximum

force)

Control 1 1 1 1 2 120

SBF1 1 1 1 1 3 140

SBF2 2 1 1 2 2 160

SBF3 1 1 1 3 1 160

SBF4 1 2 1 4 2 220

SBC 1 1 1 2 2 150

Weight of each

parameter (%)

10 10 30 30 20 100

a Values are in a scale from 1 to 6 where 1 is the best and 6 the worst grade. The same value was assigned to treatments with no

significant difference according with Tukey’s analysis (alpha


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Chuck-Hernández et al

()

()

()

()

()

()

(

)

(

)

(

)

1.00

, % 0.72 1.00

() 0.4 1.00

()

0.5 0.74 0.12 1.00

()

0.63 0.64 0.55 1.00

()

0.6 0.31 0.70 1.00

()

0.20 0.32 0.47 0.61 0.32 0.10 1.00

()

0.10 0.42 0.43 0.6 0.20 0.23 1.00

0.46 0.04 0.65 0.3 0.56 0.16 1.00

0.64 0.14 0.53 0.03 0.4 0.76 0.67 1.00

0.04 0.03 0.2 0.56 0.21 0.20 0.73 0.6 0.73 0.50 1.00

0.6 0.41 0.12 0.66 0.40 0.71 0.64 0.71 0.6 1.00

0.42 0.15 0.54 0.31 0.5 0.3 0.7 1.00

0.26 0.07 0.37 0.42 0.4 0.25 0.72 1.00

(

)

0.23 0.12 0.44 0.46 0.37 0.2 0.7 0.73 0.63 1.00

(

)

0.12 0.6 0.17 0.74 0.01 0.45 0.75 0.55 0.4 0.35 0.56 0.71 0.50 1.00

(

)

0.04 0.50 0.44 0.75 0.06 0.41 0.52 0.57 0.5 0.64 0.71 0.62 1.00

Table V. Correlation table with the main physicochemical characteristics of soy products and final parameters of maize tortillaa

1

a Correlation coefficients significant with P


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FIGURES

Fig. 1. Effect of soybean enrichment on viscoamylographic properties of water suspensions composited flours used for tortilla

production.

45

50

55

60

65

70

75

80

85

90

95

0

500

1000

1500

2000

2500

0 100 200 300 400 500 600 700 800 900 1000

T e m p e r a t u r e

( ° C )

V i s c o s i t y ( R V U )

Time (seg)

CONTROL SBF1 SBF2 SBF3

SBF4 SBC Temperature

C e r e a l C h e m i s t r y

J o u r n a l " F i r s t L o o k " p a p e r • h t t p : / / d x . d o i . o r g / 1 0 . 1

0 9 4 / C C H E M - 0 7 - 1 4 - 0 1 5 4 - R • p o s t e d 0 2 / 2 3 / 2 0 1 5

T h i s p a p e r h a s b e e n p e e r r e v i e w e d

a n d a c c e p t e d f o r p u b l i c a t i o n b u t

h a s n o t y e t b e e n c o p y e d i t e d o r p r

o o f r e a d .


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Fig. 2. Effect of soybean enrichment on luminosity of tortillas stored for five days at room temperature.

68

70

72

74

76

78

80

82

84

0 1 2 5

L u m i n o s i t y ( L )

Storage (days)

Control

SBF1

SBF2

SBF3

SBF4

SBC

C e r e a l C h e m i s t r y

J o u r n a l " F i r s t L o o k " p a p e r • h t t p :

/ / d x . d o i . o r g / 1 0 . 1

0 9 4 / C C H E M - 0 7 - 1 4 - 0 1 5 4 - R • p o s t e d 0 2 / 2 3 / 2 0 1 5

T h i s p a p e r h a s b e e n p e e r r e v i e w e d

a n d a c c e p t e d f o r p u b l i c a t i o n b u t

h a s n o t y e t b e e n c o p y e d i t e d o r p r

o o f r e a d .



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Fig. 4. Sensory evaluation of enriched tortillas produced with five different soy products.

A subjective scale was used during the sensorial trials, where

functionality and organoleptic properties of maize tortillas enriched with 1 five...

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