Tallarines salados de sémola de trigo y almidón de plátano: Composición proximal y digestibilidad del almidón in vitro

COMPOSITE WHEAT-PLANTAIN STARCH SALTED NOODLES. PREPARATION, PROXIMAL COMPOSITION AND IN VITRO STARCH DIGESTIBILITY Rodolfo Rendón-Villalobos, Perla Osorio-Díaz, Edith Agama-Acevedo, Juscelino Tovar and Luis A. Bello-Pérez SUMMARY Salted noodles were prepared with different contents of wheat grits and plantain starch (PS). The blends were hydrated with 2% NaCl (w/v), homogenized, and the resulting doughs were sheeted through a pasta machine, cut into strips ~30cm in length, cooked, and their composition and in vitro starch digestibility was assessed. Moisture (6.43-7.60%) and ash contents (2.08-3.12%) increased by the addition of PS. Fat level decreased from 0.41 to 0.31% as the substitution of wheat grits increased. Results showed a 7.39% lower total starch content

in the control sample as compared to the noodle containing 30% PS. A similar pattern was observed for potentially available starch content, but the difference was greater (12.46%). Approximately 50% of total resistant starch (RS) in the noodles was resistant starch associated to fiber, showing that a part of RS is due to the physically inaccessible and retrograded starch fractions. Pure wheat (control) noodles presented a greater final α-amylolysis value, which is suggestive of potentially lower glycemic impact for the plantain/wheat products.

Introduction

The relatively recent recog­ nition of incomplete digestion and absorption of starch in the small intestine as a nor­ mal phenomenon has raised interest in non-digestible starch fractions (Englyst et al., 1992; Aparicio-Saguilán

Starch, which is the major dietary source of carbohydrates, is also the most abundant stor­ age polysaccharide in plants. It occurs as granules in the chloroplast of green leaves and

the amyloplast of seeds, pulses, and tubers. Starch is a major component of wheat grain; it is located in the endosperm and has some unique properties, which determine its functional­ ity in many food applications (Shibanuma et al., 1994).

et al., 2007). These are called resistant starches (RS), and numerous studies have shown them to have physiological functions similar to those of dietary fiber (Asp, 1994). Therefore, products containing high levels of RS might well

KEYWORDS / Chemical Composition / Digestibility / Pasta / Plantain / Starch / Received: 10/30/2007. Modified: 07/25/2008. Accepted: 07/28/2008.

Rodolfo Rendón-Villalobos. Bio­ logist, Universidad Autónoma del Estado de Morelos, Mexico. M.Sc. in Marine Ecology, Centro de Investigación Científica y de Educación Superior de Ensenada, Mexico. Researcher, Centro de Desarrollo de Productos Bióticos (CEPROBI-IPN), Mexico. Perla Osorio-Díaz. Nutritionist and M.Sc. in Food Science and

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Technology, Instituto Politécnico Nacional (IPN), Mexico. Ph.D. in Food Science and Technology, Universidad Autónoma de Queré­ taro (UAQ), Mexico. Researcher, CEPROBI-IPN, Mexico. Edith Agama-Acevedo. Bio­ chemical Engineer, Institu­ to Tecnológico de Acapulco (ITA), Mexico. M.Sc. in Biotic Product Development, CEPRO­

BI-IPN, Mexico. Ph.D. in Food Science and Technology, UAQ, Mexico Researcher, CEPROBIIPN, Mexico. Juscelino Tovar. Biologist, Uni­ versidad Central de Venezuela (UCV). Ph.D. in Applied Nutri­ tion, University of Lund, Sweden. Professor, UCV, Venezuela. Luis A. Bello-Pérez. Biochemical Engineer, ITA, Mexico. M.Sc.

0378-1844/08/09/658-05 $ 3.00/0

in Bio-engineering and Ph.D. in Plant Biotechnology, CON­ VESTAV-IPN. Professor, CEP­ ROBI-IPN, Mexico. Address: CEPROBI-IPN, Apartado 24 C.P., 62731, Yautepec, More­ los, México. e-mail: labellop@ ipn.mx

SEP 2008, VOL. 33 Nº 9

TALLARINES SALADOS DE SÉMOLA DE TRIGO Y ALMIDÓN DE PLÁTANO. COMPOSICIÓN PROXIMAL Y DIGESTIBILIDAD DEL ALMIDÓN IN VITRO Rodolfo Rendón-Villalobos, Perla Osorio-Díaz, Edith Agama-Acevedo, Juscelino Tovar y Luis A. Bello-Pérez RESUMEN Se elaboraron tallarines salados con diferentes contenidos de sémola de trigo y almidón de plátano (AP). Las mezclas fueron hidratadas con solución NaCl 2% (p/v), homogenizadas y las masas laminadas en una máquina para elaborar pasta. Se cortaron en tiras de ~30cm de longitud, se cocinaron y se estudió su composición, así como la digestibilidad del almidón in vitro. El contenido de humedad (6,43-7,60%) y cenizas (2,08-3,12%) incrementaron con la adición del AP. El contenido de lípidos disminuyó de 0,41 a 0,31% conforme el nivel de sustitución de la semolina incrementó. El contenido de almidón total fue

7,39% menor en la muestra control comparado con el tallarín con 30% de AP. Un comportamiento similar se encontró en el almidón disponible, pero la diferencia fue mayor (12,46%). Aproximadamente 50% del almidón resistente total (AR) en los tallarines fue almidón resistente asociado a fibra, mostrando que una parte del AR es debido al almidón físicamente inaccesible y al almidón retrogradado. El valor final de la α-amilólisis fue mayor en el control de trigo puro, lo cual sugiere que los tallarines elaborados con la mezcla semolina/AP tienen menor impacto glucémico.

TalHarins salGados de sÊmola de trigo E amidO de BANANA DA TERRA. ComposiÇÃO proximal E digestibilidadE dO amidO in vitro Rodolfo Rendón-Villalobos, Perla Osorio-Díaz, Edith Agama-Acevedo, Juscelino Tovar e Luis A. Bello-Pérez RESUMO Elaboraram-se talharins salgados com diferentes conteúdos de sêmola de trigo e amido de banana da terra (ABT). As misturas foram hidratadas com solução NaCl 2% (p/v), homogeneizadas e as massas laminadas em uma máquina para elaborar massa. Cortaram-se em tiras de ~30cm de comprimento, foram cozidas e estudada sua composição, assim como a digestibilidade do amido in vitro. O conteúdo de umidade (6,43-7,60%) e cinzas (2,08-3,12%) se incrementou com a adição de ABT. O conteúdo de lipídios diminuiu de 0,41 a 0,31% na medida em que o nível de substituição da semolina se incrementou. O conteúdo de

qualify as functional foods, which could be manufactured in great variety and with high palatability. Among the richest natural sources of resistant starch (RS), fruits of plants from the Musa genus are of particular importance (Faisant et al., 1995; Bello-Pérez et al., 2004). Unripe banana flour, for in­ stance, contains between 47 and 57% RS, depending on the analytical method employed (Faisant et al., 1995). More recently, an RS level of 17.5% was recorded for the flour of a plantain variety (JuárezGarcía et al., 2006). With nearly 40% of wheat being processed into noodle products in Asian countries (Baik and Lee, 2003), the consumption of wheat noodles is, globally, second only to bread. The in­ stant noodle market is grow­ ing fast in Asian countries, and is gaining popularity in the Western market (Yu and

Ngadi, 2004). Depending on the method of dehydration, instant noodles can be divided into fried and non-fried types (Wu et al., 1998). Fried instant noodles are made by a contin­ uous steaming and frying pro­ cess that gelatinizes starch and quickly dehydrates the noodles. The resulting product has a porous spongy structure and an excellent flavor. Non-fried instant noodles can be dehy­ drated after expansion from a tight non-expanded structure, or using high-temperature ex­ pansion to produce a porous, honeycomb-like structure, e.g., the expanded type (Wu et al., 1998). Wheat grits is the main ingredient for making Asian noodles (Baik and Lee, 2003). About three parts of flour are usually mixed with one part of salt or alkaline salt solution to first form a crumbly dough and then “white salted noodles”. In Japan, instant noodles, which

SEP 2008, VOL. 33 Nº 9

amido total foi 7,39% menor na amostra controle comparado com o talharim com 30% de ABT. Um comportamento similar se encontrou no amido disponível, mas a diferença foi maior (12,46%). Aproximadamente 50% do amido resistente total (AR) nos talharins foi amido resistente associado à fibra, mostrando que uma parte do AR é devido ao amido fisicamente inacessível e ao amido retrogradado. O valor final da α-amilólisis foi maior no controle de trigo puro, o qual sugere que os talharins elaborados com a mistura semolina/ABT têm menor impacto glicêmico.

are steamed, deep fat-fried and packed in polyethylene bags, are a popular industri­ ally processed food. Chinesetype alkaline instant noodles, called “instant ramen”, are manufactured in the highest quantity. The ingredients of instant noodles are wheat grits, starch, salt, alkali (soda/pot­ ash) and water (Noda et al., 2006). Park and Baik (2004) observed the significance of the amylose content of starch in wheat grits with respect to the textural properties of in­ stant noodles. They indicated that there was a positive cor­ relation between the hardness of cooked instant noodles and the amylose content. Variations in suitability as a material for the production of starch-based noodles were found among starch samples prepared from several potato cultivars (Singh et al., 2002). On the other hand, Batey et al. (1997) have confirmed the importance of

the starch component, report­ ing significant correlations be­ tween textural properties of alkaline noodles and selected flour pasting characteristics or swelling parameters derived of flour or whole meal. However, information on starch digest­ ibility in white salted noodles is yet rather scarce. The objectives of this re­ search were to prepare plan­ tain starch-containing noodles and evaluate its proximal com­ position. The impact of adding different plantain starch levels on the in vitro digestibility of starch in the noodles was also evaluated. Materials and Methods Starch isolation Unripe plantains (Musa paradisiaca L.) were purchased at the local market of Cuautla, Morelos State, Mexico. Starch was isolated by the procedure

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described by Flores-Goros­ quera et al. (2004). Preparation of White Salted Noodles White salted noodles (WSN) were prepared by mixing of wheat grits and plantain starch in proportions of 90:10, 80:20 and 70:30, respectively. Con­ trol WSN was prepared with 100% wheat grits. The con­ trol sample and blends were mixed with enough 2% NaCl (w/v) to obtain a completely hydrated flour. Mixing was carried out in an N50 mixer (Hobart, North York, Cana­ da) for 5min using low speed (speed position 1). The mixed dough was sheeted through the rolls of a pasta machine with a gap setting of 3.0mm. After the first pass, the noodle sheet was folded and passed twice through the rollers at this same setting. The dough sheet was cut through #12 cutting rolls into strips ~30cm in length and cross-section of 0.3× 0.2cm. The result­ ing noodle strip was placed uniformly into a steam pan and then put into a preheated (100°C) steamer, and cooked for 12min until the noodle strip had a smooth surface and an elastic texture, as it is normally consumed, according to the finger test. All samples were frozen in liquid nitro­ gen, freeze dried and stored at room temperature in sealed plastic containers. Chemical analysis Moisture content was deter­ mined by gravimetric heating (130 ±2ºC for 2h) using a 2-3g sample. Ash, protein, fat and dietary fiber were analyzed according to AACC meth­ ods 08-01, 46-13, 30-25, and 32-05, respectively (AACC, 2000). These analyses were carried out in quadruplicate in a completely randomized design. Starch content Total starch content in the noodles was assessed accord­ ing to Goñi et al. (1997).

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Samples of 50mg were dis­ persed in 3ml distillated water and 3ml of 4M KOH. The mixture was intensely stirred with a magnetic bar during 30min at room tem­ perature. After neutralization, the mixture was treated with amyloglucosidase (Boehringer, Mannheim, Germany) in order to release glucose, which was measured colorimetrically us­ ing the glucose oxidase per­ oxidase assay (SERA-PAK® Plus, Bayer de México). Starch analyses were performed in triplicate. In vitro digestibility tests The content of potentially available starch was assessed following the multienzymat­ ic protocol of Holm et al. (1986). Brief ly, the sample was treated with a heat-stable α-amylase (Termamyl® Novo A/S, Copenhagen) in a boiling water bath for 20min and then with amyloglucosidase (Boeh­ ringer, Mannheim, Germany). Released glucose was ana­ lyzed using the glucose-oxi­ dase-peroxidase (GOD/POD) system. Resistant starch (RS) was measured by two dif­ ferent protocols: 1) The con­ tent of RS associated to fiber (RSAF or RS3) was measured as starch remnants in dietary fiber residues, according to the so called “Lund method” as modified by Saura-Calixto et al. (1993); 2) the method pro­ posed by Goñi et al. (1996) was employed to estimate the total amount of indigestible starch (comprising RS2, RS3 and part of RS1 fractions; Tovar, 2001). In brief, removal of protein with pepsin P-7012 (Sigma Chemical, St. Louis, MO, USA) was followed by incubation with α-amylase A-3176 (Sigma) to hydrolyze digestible starch; after this, the insoluble material was treated with 2M KOH in or­ der to disperse the resistant starch, which was immedi­ ately digested with amylo­ glucosidase A-7255 (Sigma). Finally, released glucose was determined using the glu­ cose oxidase/peroxidase assay (SERA-PAK® Plus, Bayer de

TABLE I COMPOSITION OF WHITE SALTED NOODLES CONTAINING DIFFERENT PLANTAIN STARCH LEVELS Sample Control 10% 20% 30%

Moisture (%) 6.43 5.68 7.03 7.60

±0.12 ±0.17 ±0.18 ±0.11

Fat (%)1 a b a,c c

0.41 0.34 0.31 0.33

±0.03 ±0.01 ±0.02 ±0.03

Protein (%)1 a a a a

13.62 12.01 10.84 10.18

±0.01 ±0.15 ±0.19 ±0.04

Ash (%)1 a b c c

2.08 2.28 2.31 3.12

±0.11 ±0.02 ±0.04 ±0.02

a a a b

Composition expressed on a dry weight basis. Values are mean of duplicates ±SEM. Values followed by the same letter within a column are not significantly different (P>0.05, Tukey test). 1

México). The in vitro rate of α-amylolysis was meas­ ured according to Holm et al. (1985). The percentage of digested starch was estimated at different incubation times from the maltose produced, assessed with the 3,5-dini­ tro-salicylic acid (DNS) acid reaction. Each assay was run with 500mg available starch. All in vitro digestibility tests were performed in duplicate on noodles cooked (boiled) as for eating. The α-amylolysis assays were carried out with homogenized cooked noodles. Statistical analysis The results are presented as mean ±SEM. A commer­ cial software program (Sigma Stat ver. 2.03, Jandel Corpora­ tion, San Rafael, CA, USA) was used to conduct two-way analysis of variance (ANOVA) for determining significant differences among means. Statistically significant differ­ ences (p