Journal of Food Quality

Journal of Food Quality / 2017 / Article

Research Article | Open Access

Volume 2017 |Article ID 8627363 | https://doi.org/10.1155/2017/8627363

María Gricelda Vázquez-Carrillo, David Santiago-Ramos, Edith Domínguez-Rendón, Marco Antonio Audelo-Benites, "Effects of Two Different Pozole Preparation Processes on Quality Variables and Pasting Properties of Processed Maize Grain", Journal of Food Quality, vol. 2017, Article ID 8627363, 15 pages, 2017. https://doi.org/10.1155/2017/8627363

Effects of Two Different Pozole Preparation Processes on Quality Variables and Pasting Properties of Processed Maize Grain

Academic Editor: Alejandro Hernández
Received06 Jul 2016
Revised26 Sep 2016
Accepted23 Oct 2016
Published12 Jan 2017

Abstract

The effects of two different pozole preparation processes, traditional (TP) and industrial (IP), on quality variables, chemical composition, and pasting properties of processed grain of nine maize landraces were evaluated. Nixtamalization and steeping time in TP (~15 h) allowed more water absorption resulting in higher moisture content as well as softer debranned nixtamal relative to the debranned nixtamal produced by IP (52 min). Steeping in TP and bleaching in IP increased the pasting temperature, peak viscosity, and time to peak viscosity of maize starch. Flowering time was shorter in IP (<120 min) than in TP (>120 min) and was significantly affected by the hardness of debranned nixtamal and bleached precooked grains. Total dry matter loss was higher in IP (>10.5%) than in TP (<5.0%), mainly due to the complete elimination of pedicel and pericarp by the Ca(OH)2 + NaOH solution during cooking. Soft grains, with low test weight, a high proportion of floury endosperm, and high peak viscosity, are required to obtain higher yield of bleached precooked grains and soft flowered grains in both processes.

1. Introduction

Pozole is a pre-Columbian dish widely consumed in Mexico and in the United States by people of Latin American origin [1]. The production of maize for pozole preparation and the consumption of this dish have increased in recent years [2].

The main ingredient of pozole is boiled maize in the form of “flowered grain.” There are two different processes involved in obtaining flowered grains for pozole: the traditional process (TP) and the commercial or industrial process (IP) [3]. Both processes begin with nixtamalization, a thermal-alkaline treatment whose principal purpose is to remove the pedicel and pericarp from the grain. In TP, nixtamalization is carried out with Ca(OH)2, which hydrolyzes the pericarp, while, in IP, a mixture of Ca(OH)2 and NaOH is used to remove both the pedicel and pericarp. In TP, the cooked grain (nixtamal) is steeped for 8–16 h. It is then washed to eliminate the pericarp as well as the pedicel (deheaded), and finally the debranned nixtamal is boiled, causing the grain to swell and open up into a flower shape (flowered grain) [1, 36]. In IP, the debranned nixtamal is washed and the pedicel is removed immediately (deheaded). The grains are then bleached in a solution of sodium metabisulfite (Na2S2O5) and acetic acid (CH3COOH) and packed, obtaining a product ready to be cooked (bleached precooked grain) until it flowers when used by the end consumer [2, 3].

In Mexico, about sixteen maize landraces are used in the preparation of flowered grains for pozole [2, 710]. Many of these landraces, including Cacahuacintle, Ancho, Elotes Occidentales, and Jala, are known as “specialty maize landraces,” which means they are preferred over hybrids or improved varieties for the preparation of specific food or dishes like pozole [2, 8, 10, 11].

Bonifacio Vázquez et al. [4] studied the relationship between physical grain characteristics of the Cacahuacintle landrace and the quality of the flowered grain for pozole prepared by TP. They found that the shape, size, and density of the grain affect flowering time and flowered grain quality. The larger and globose-shaped grains require less flowering time and result in a better quality product. Figueroa et al. [1] reported that the peak viscosity of the grain is a good parameter in predicting flowered grain yield by TP, due to the significant correlation found between those two variables (, ). On the other hand, Figueroa et al. [1, 5] reported that the annealing process is carried out in the steeping step of TP. This phenomenon has two important implications: (1) an increase in the gelatinization temperature and pasting temperature of the nixtamal starch, which increases the stability of the starch granules and their ability to resist collapse during boiling, and (2) an increase in viscosity, swelling, and the hydration capacity of the starch granules, resulting in a soft texture and a high yield of pozole [1, 5].

Industrial processing has greater economic and technological implications. Vázquez-Carrillo and Santiago-Ramos [3] reported that IP reduces processing time and energy consumption considerably, and it may also reduce nutritional quality. However, the effect of this process on the quality variables of the resulting products and on the properties of starch and other grain components is still unknown.

Keleman and Hellin [8] and Hellin et al. [10] noted that research on maize landraces has focused on yield and agronomic features while aspects of grain quality and culinary potential have been given less attention, so it is necessary to expand the scope of research and determine the potential of each maize landrace for specialty markets in this case, the best landraces for pozole, which could generate more income for farmers and prevent the extinction of some landraces through “conservation in situ” or “conservation through use.” Regarding processors, some industries that produce bleached precooked grain also opt to use hybrids, varieties, and landraces grown commonly for making tortillas such as Tuxpeño, Cónico or Chalqueño, due to their low price and wide availability, and then mix them with the other landraces. However, the effect of this process on these types of maize and how it affects the quality of pozole are unknown.

The objective of this study was to evaluate the effects of two different pozole preparation processes, industrial and traditional, on the quality variables and pasting properties of the debranned nixtamal, bleached precooked grain, and flowered grain of maize.

2. Materials and Methods

2.1. Materials

Nine maize landraces were assessed. Eight landraces are well documented as being used in the preparation of pozole: Cacahuacintle, Ancho, Tabloncillo, Jala, Bofo-Harinoso de Ocho, Bolita, Chalqueño, and Tuxpeño [2, 710]. Cónico was used for purposes of comparison. Tuxpeño and Cónico are landraces such that their main use is the preparation of tortillas, but, as mentioned in the Introduction, some industries that produce bleached precooked grain also opt to use these types of maize due to their low price and wide availability. The samples correspond to a collection of each landrace harvested in 2011 in the following locations: Cacahuacintle from Topilejo, Ciudad de Mexico; Ancho from Iguala, Guerrero; Tabloncillo from Obregón, Sonora; Jala from Jala, Nayarit; Bofo-Harinoso de Ocho from El Roble, Nayarit; Bolita from Etla, Oaxaca; Chalqueño from Ayapango, Estate of Mexico; Tuxpeño from Sinaloa; and Cónico from Los Reyes, Tlaxcala. Two commercial samples of bleached precooked grain were used as controls, and these were obtained at the local market.

2.2. Physical Grain Characteristics

Test weight (TW) was determined by weighing a fixed volume (1 L) of grain from a test weight filling hopper (Ohaus® Model 150, Florham Park, NJ, USA) according to the 55-10.01 AACC International Method [12]. Hundred-grain weight (HGW) was measured by weighing 100 grains in an analytical balance Ohaus Model TS400S (Florham Park, NJ, USA); this variable was used as an indirect measure of grain size. Flotation index (FI) was determined with the method described in the norm NMX-FF-034/1-SCFI-2002 [13], which consists of placing 100 grains in a beaker containing 300 mL of NaNO3 solution (1.250 g/mL), grains were stirred and left standing for 1 min, and finally the number of floating kernels was recorded. TW, HGW, and FI are affected by the moisture content of the sample, so they were adjusted at 12% moisture content by using the following equations:Moisture content was determined by the dielectric meter method  44-11.01 of the AACC International [12] using 250 g in a Steinlite Moisture Tester SS250 (Atchison, KS, USA).

Percentages of pedicel, pericarp, germ, floury endosperm, and vitreous endosperm were determined by hand-dissection. Twenty-five grains were soaked in 50 mL of distilled water at 60°C for 30 min, and then with a scalpel each structure was separated. Grain fractions were dried for 12 h in an oven at 100°C to express the percentage in dry basis [5].

Pericarp thickness (PT) was measured following the method described by Wolf et al. [14]. Five kernels were steeped in water for 4 h at room temperature, and then crown cap and tip cap were cut and removed. Pericarp of each grain was peeled as strips and placed at room temperature for 24 h to dry. Pericarp thickness was measured with a micrometer at the position opposite to germ and was reported as the mean of five strips in μm.

Grain luminosity () was determined with the colorimeter Hunter Lab MiniScan XE Plus Model 45/0-L® (Reston, VA, USA), with a D/65 illuminant and a 10° angle. The colorimeter was calibrated with a standard white tile and samples were placed randomly in a 5.5 cm diameter plastic cell with an optically clear glass bottom, according to the method reported by Floyd et al. [15].

All variables were analyzed in duplicate.

2.3. Samples Preparation: Traditional and Industrial Processes

Two batches of each sample were run. Two different processes were used to obtain flowered grains for pozole preparation: the traditional process (TP) and the industrial process (IP) (Figure 1), based on the methodology described by Vázquez-Carrillo and Santiago-Ramos [3].

2.3.1. Traditional Process

For nixtamalization, 100 g of clean, uniform-size maize grains was cooked with 0.7 g Ca(OH)2 and 200 mL distilled water. Nixtamalization time was established as a function of the FI of each sample and measured from the moment the mixture began to boil. After cooking, the samples were steeped for 14 h, after which the cooking solution (nejayote) was discarded. The nixtamal was washed with dap water until all of the pericarp was eliminated and each grain was deheaded. Nixtamal grain without pericarp and pedicel was named “debranned nixtamal.” Finally, each sample was boiled with 450 mL distilled water to allow the grain to swell and open up into a flower shape (become flowered). Flowering time concluded when at least 6 grains (60%) of a sample of 10 had flowered.

2.3.2. Industrial Process

In the industrial process, 100 g of maize was cooked initially with 200 mL distilled water with 0.7 g Ca(OH)2. After two min of boiling, 4 mL of a solution of 50% NaOH (w/v) was added. Nixtamalization of all of the samples lasted 50 min; time was recorded starting from the addition of NaOH. Once the nixtamalization process ended, the cooking solution (nejayote) was discarded and the cooked grain (nixtamal) was washed until all of the pedicel and the pericarp were eliminated. The debranned nixtamal was then bleached in 200 mL distilled water at 70°C with 6 g Na2S2O5. When the mixture temperature cooled to 50°C, 2 mL CH3COOH was added and the mixture was left to stand for 20 h. After this period, the solution was discarded and the bleached precooked grain was flowered in the same manner as in the TP.

2.4. Quality Variables of Debranned Nixtamal, Bleached Precooked Grain, and Flowered Grains
2.4.1. Debranned Nixtamal (DN)

DN yield was expressed as kg of DN obtained from each kg of unprocessed maize [1, 3]. DN expansion volume was calculated as the difference between the final DN volume and the initial grain volume [3]. DN moisture content was determined with method  44-19.01 of AACC International [12]. DN hardness, expressed as maximum puncture force, was obtained from 10 grains with a texturometer Brookfield® Model CT3 (Middleboro, MA, USA) equipped with a needle 1.0 mm in diameter and 45 mm long. The assessment parameters were speed 2 mm/s and 5 mm penetration. Luminosity () of the DN was measured with the colorimeter Hunter Lab MiniScan XE Plus Model 45/0-L (Reston, VA, USA), with a D/65 illuminant and a 10° angle, following the same procedure used in the measurement of grain luminosity [15]. Loss of dry matter in the cooking solution (nejayote) due to the nixtamalization process was quantified as the residual dry matter left after each solution evaporated.

All variables were analyzed in duplicate for each batch, except for hardness where 10 grains were analyzed.

2.4.2. Bleached Precooked Grain

Bleached precooked grain yield was reported as kg of bleached precooked grain per kg of unprocessed maize. Precooked grain expansion volume was calculated as the difference between the final volume of precooked grain and initial grain volume. Moisture content was determined with AACC International Method  44-19.01 [12], and precooked grain luminosity and hardness were determined as described above. Loss of dry matter in the solution of the bleaching process was quantified as the residual dry matter left after each solution evaporated.

All variables were analyzed in duplicate for each batch, except for hardness where 10 grains were analyzed.

2.4.3. Flowered Grains

Flowered grain yield was reported as kg of flowered grain per kg of unprocessed maize [1, 3]. Flowered grain expansion volume was calculated as the difference between the final volume of flowered grain and initial grain volume. Moisture content was determined with AACC International method  44-19.01 [12]. Flowered grain hardness and luminosity were determined as described above. Flowering time was defined as the time necessary for at least 60% of the grains to take on the appearance of a flower [4]. Flowered grain solution viscosity was measured using the viscometer Brookfield DV-II+Pro® (Middleboro, MA, USA) in 200 mL solution samples at 25°C with a stainless steel cylindrical probe LV-1 (61) at a rotation rate of 50 rpm. Measurements were taken in duplicate when the reading stabilized.

All variables were analyzed in duplicate for each batch, except for hardness where 10 grains were analyzed.

2.5. Pasting Properties of Grain, Debranned Nixtamal, Bleached Precooked Grain, and Flowered Grain

At the end of each stage of each process, a sample of 50 g of debranned nixtamal, bleached precooked grain, and flowered grain was taken and subjected to a dehydration process in an oven for 24 h at 40°C. Then, a 15 g sample was ground in a FOSS Cyclotec 1093 Mill (Zhanye Rd, SIP, Suzhou, China) and passed through a US #60 mesh. Pasting properties of the whole grain, debranned nixtamal, bleached precooked grain, and flowered grain were obtained with a method based on Narváez-González et al. [16] using a Rapid Visco Analyzer (RVA) (Super 4, Newport Scientific Pty Ltd., Sydney, Australia). In aluminum receptacles, 4 g of flour was mixed with 24 mL distilled water (adjusting moisture to 14%). The mixture was heated from 50 to 90°C in 9.0 min, and cooking was maintained at 90°C for 5 min. Finally, it was cooled to 50°C in 9.0 min. Shaking speed was 160 rpm.

All variables were analyzed in duplicate for each batch.

2.6. Chemical Composition of Grain, Debranned Nixtamal, Bleached Precooked Grain, and Flowered Grain

Crude protein content was determined by Kjeldahl nitrogen analysis () (AACCI Method  46-16.01), crude fat by extraction with petroleum ether (AACCI Method  30-25.01), ash by dry combustion (AACCI Method  08-01.01), and crude fiber by acid-alkaline digestion (AACCI Method  32-10-01) [12]. Carbohydrates were determined by difference (100 − % crude protein − % crude fat − % ash − % crude fiber). Total starch content was determined with a Megazyme total starch assay kit (Megazyme, Bray, Ireland) based on AACCI Approved Method  76-13.01 [12], and amylose was determined according to the method reported by Hoover and Ratnayake [17]. All variables were analyzed in duplicate for each batch, except for starch and amylose content where three analytical replicates were run.

2.7. Statistical Analysis

The experimental design was completely randomized for the physical and chemical variables of the grain and factorial for quality variables, proximate composition, and pasting properties of processed grains. The results were analyzed with an analysis of variance, comparison of means (Tukey, ), and simple Pearson correlation in SAS software for Windows, version 9.0.

3. Results and Discussion

3.1. Physical Grain Characteristics and Chemical Composition

Physical grain characteristics and chemical components were significantly different () among the assessed landraces (Tables 1 and 2).


Landrace (kg hL−1) (g) (%) (%) (%) (%) (%) (%) (μm)

Ancho
Bofo-Harinoso de Ocho
Bolita
Cacahuacintle
Chalqueño
Cónico
Jala
Tabloncillo
Tuxpeño

: test weight; HGW: hundred-grain weight; FI: flotation index; PED: pedicel; PER: pericarp; GER: germ; FE: floury endosperm; VE: vitreous endosperm; PT: pericarp thickness; and : luminosity.
The number in parenthesis indicates the number of analytical replicates performed to obtain the results of each parameter.
Means followed by the same letter in the same column are not significantly different (Tukey, ).

LandraceCrude fa (%)Crude protei (%)As (%)Crude fibe (%)Carbohydrate (%)Total starc (%)Amylos (%) Amylopecti (%)

Ancho
Bofo-Harinoso
de Ocho
Bolita
Cacahuacintle
Chalqueño
Cónico
Jala
Tabloncillo
Tuxpeño

The number in parenthesis indicates the number of analytical replicates performed to obtain the results of each component.
Means followed by the same letter in the same column are not significantly different (Tukey, ).

Cacahuacintle had the lowest test weight (TW), large and very soft (FI = 100) grains, and the highest proportion of floury endosperm (FE = 80.4%). Similar results with collections of the same landrace were reported by other authors [1, 2, 5, 6]. Ancho and Bofo-Harinoso de Ocho were characterized by low TW and very soft grains. In contrast, some landraces, such as Tuxpeño and Cónico (commonly used for making tortillas) had high TW (>74 kg hL−1), intermediate to soft hardness according to norm NMX-FF-034/1-SCFI-2002 [13], small grains, and larger proportion of vitreous than of floury endosperm. It was also observed that grains from landraces little used to make pozole (Cónico, Tuxpeño, and Bolita) had high contents (>8.0%) of fibrous structures (pedicel and pericarp) resulting in a higher content of crude fiber (Tables 1 and 2). Grains of the landrace Bofo-Harinoso de Ocho had the highest percentage of germ (13.7%) and the highest lipid content (Tables 1 and 2). According to Figueroa et al. [1], this has highly important technological implications because these lipids can participate in the formation of amylose-lipid complexes during boiling in TP, increase starch granule stability at collapse, and affect the properties of the end product. Pericarp thickness varied between 102 and 111 μm. These values coincided with those reported by Wolf et al. [14] but were higher than those reported by Narváez-González et al. [18]. Differences are attributed to the method used to determine pericarp thickness. Ancho and Cacahuacintle had the whitest grains () (Table 1).

Contents of crude fat, crude protein, and ash were close to the ranges reported by Narváez-González et al. [18] for a large number of Mexican landraces. Tabloncillo had the highest content of protein and ash (Table 2). The carbohydrate content was higher in Cacahuacintle (Table 2); similar results were reported by Figueroa et al. [5]. Landraces with very soft grains (Cacahuacintle and Bofo-Harinoso de Ocho) had the highest total starch content and the lowest content of amylose according to the trend reported by Dombrink-Kurtzman and Knutson [19].

3.2. Effect of Process on Quality Variables and Chemical Components of Debranned Nixtamal, Bleached Precooked Grain, and Flowered Grain

Quality variables and chemical components of debranned nixtamal, bleached precooked grain, and flowered grain were significantly different () between treatments due to the effects of different processes, landrace type, and process by landrace interaction. The exceptions were the ash content in debranned nixtamal obtained by industrial process (Table 3), dry matter loss due to bleaching process (DMLB) (Table 4), and crude fiber content in flowered grains (Table 5).


ProcessLandrace (kg/kg)EVN (cm3) (%) (N) (%) (%) (%) (%)Crude (%) (%)

Traditional (TP)Ancho
Bofo-Harinoso de Ocho
Bolita