Abstract
Increasing dietary fiber (DF) intake may help to decrease risk of chronic diseases such as diabetes, cardiovascular disease and colon cancer. The objective of this work was to study and compare the chemical composition and physicochemical properties of some products used as DF sources. The DF source products evaluated were Metamucil, Kania, Tarasca, Nopalinaza, Xotzil and dried shiitake mushroom (Lentinus edodes). Metamucil showed the highest content of DF (52.72%), followed by Kania (50.57%) and DS (49.09%). Also, Metamucil, Kania and DS showed the highest water absorption values 15.9, 8.5, and 5.7 g water/g sample respectively, while DS showed the highest oil absorption capacity (3.1 g oil/g sample). Best values delaying diffusion of glucose were obtained in Metamucil, Nopalinaza, Kania and DS samples. Multiple correlation analysis indicated that soluble fiber contents positively correlated with water absorption capacity, viscosity and minor particle size.
El incremento del consumo de fibra dietética (FD) puede ayudar a prevenir enfermedades crónico-degenerativas como la diabetes, enfermedad cardiovascular y el cáncer de colon. El objetivo de este trabajo fue hacer una caracterización química y físico-química de algunos productos usados como fuente de FD. Los productos evaluados fueron el Metamucil, Kania, Tarasca, Nopalinaza y Xotzil, así como el hongo shiitake (Lentinus edodes) deshidratado (SD). El Metamucil mostró el mayor contenido de FD (52,72%), seguido de Kania (50,57%) y el SD (49,09%). Además, los productos Metamucil, Kania y SD mostraron los mayores valores de capacidad de absorción de agua, 15,9, 8,5, y 5,7 g agua/g muestra, respectivamente. Mientras que el SD presento la mayor capacidad de absorción de aceite (3,1 g aceite/g muestra). Los productos Metamucil, Nopalinaza, Kania y SD fueron efectivos para retardar la difusión de glucosa. El Análisis de Correlación Múltiple indicó que la fibra soluble correlacionó positivamente con la capacidad de absorción de agua, la viscosidad y el menor tamaño de partícula.
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Introduction
Dietary fiber (DF) is an important factor in diet, since it provides many physiological functions in human beings, such as the regulation of intestinal motility, prevention of constipation and regulation of glucose and blood lipids levels (Theander, Westernlund, & Aman, Citation1993). DF is defined as the edible remains of plants and analog carbohydrates that resist digestion and absorption into the human small intestine with partial or complete fermentation in the large intestine (Prosky, Citation1999).
One of the most important fiber classifications is related to its capacity to dissolve or disperse in water: insoluble fiber (IF) and soluble fiber (SF). IF consists of substances such as cellulose, hemicellulose, lignin, cutin, suberin, chitin and chitosan which do not dissolve in water. The components of this type of fiber resist the action of intestinal microorganisms. Its main effect in the organism is to reduce the intestinal transit time of the food and increase the fecal mass, which facilitates defecation and prevents constipation. It is also related to the prevention of colon cancer. On the other hand, SF is composed mainly of pectins, gums, β-glucans and inulins, all of which have the capacity to disperse in water forming viscous gels in the intestinal tract that give greater volume to the feces. These substances are utilized by intestinal microorganisms through fermentation. The presence of SF in the diet acts mainly upon the metabolism of lipids and glucose. This type of fiber can regulate the intestinal absorption rate of glucose and cholesterol in blood (Nelson, Citation2001).
Traditional sources of DF are wholegrains, fruit and vegetables. However, new alternative sources of DF are required in order to increase the diversity of ingredients available in products with high content of DF (Nelson, Citation2001).
Edible mushrooms, like shiitake (Lentinus edodes), represent an alternative source of DF. Shiitake has been grown for centuries in China and Japan and it is currently produced on a large scale in many parts of the world such as the United States (Brauer, Kimmons, & Phillips, Citation2002), Europe and the UK (Sadler, Citation2003), as well as Central America and the Caribbean (Hibett, Citation2001). It is also grown in different regions of Mexico, including the states of Mexico, Puebla, Querétaro, Michoacán and Tamaulipas. Mattila, Salo-Vaananen, Aro, and Jalava (Citation2002) and Beelman, Royse, and Chikthimmah (Citation2004) found a DF content of 39.3% and 47.3%, respectively, in shiitake mushrooms. The DF components of shiitake are both of the soluble and insoluble types, in particular chitin and β-glucan.
The objective of this work was to characterize and compare the chemical composition and physicochemical properties of shiitake mushroom with other commercial products used as DF source.
Materials and methods
Raw materials
Shiitake mushroom was obtained in Tiripetío, Michoacán state. The commercial products: Metamucil™ (Procter & Gamble, Cincinnati OH, USA), Fibra Kania™ (Kania & Co. S.A. de C.V., Guadalajara, Jalisco, México), Fibra Tarasca™ (Un Nuevo Amanecer, Morelia, Michoacán, México), Xotzil Fibra™ (Siempre Positivo, Zapopan, Jalisco, México), Nopalinaza Plus™ (Distribuidora Mayorista El Edén de B.C., Ensenada, Baja California, México) were bought in different stores in Morelia, Michoacán state, México.
Dehydration of shiitake mushroom
A fresh mushroom was washed with distilled water and immersed into boiling water at 98 °C for 3 min. Then, it was dried in an oven (Felisa model FE-291 D), at 65 °C for 24 h. The dried mushroom was ground in a knife mill (model GM200, Haan, Germany) and stored at 4 °C for later analysis.
Chemical composition
The moisture, ash, protein and fat contents were determined in triplicate by official methods (AACC, Citation2000). Total dietary fiber (TDF), IF and SF were measured following the method of Prosky, Asp, Schweizer, Furda, and Devries (1998). Nitrogen-free extract was determined as N.F.E. = 100 − (% protein + % ether extract + % ash + total DF).
Physico-chemical properties
The water absorption capacity (WAC) was measured according to the Sosulski (1962) method. A 1 g sample was placed in a previously weighed 50 ml centrifuge tube. Then, 10 ml of distilled water were added and stirred homogeneously with a glass rod, and centrifuged at 2500 rpm for 10 min at room temperature (22 °C) using a Model PR-J centrifuge from International Equipment Company, USA. The supernatant was decanted and the residue was weighed together with the centrifuge tube. The WAC values were expressed as gram of water absorbed/gram of the sample. A similar method was used to measure oil absorption capacity (OAC) using 1 g of sample with 10 ml of corn oil. The OAC values were expressed as gram of oil absorbed/gram of the sample.
The viscosity was measured, taking a sample of 9 g of each fiber and homogenizing it with 600 ml. Each solution was stirred for 30 min and the viscosity was measured at 25 °C using a Brookfield LVDV-II + pro viscometer (Brookfield Engineering Lab, Stoughton, MA, USA). A LV 1 spindle was used.
For the glucose diffusion delay capacity (GDDC) test, the method of Shiyi, Kin-Chor, Yan, and Liang (Citation2001) was used. Ten millilitres of a glucose solution 50 mmol/l containing 0.2 g of each sample were placed in 11 cm cellulose dialysis bags for measurement. Each sample (0.2 g) was previously hydrated in the glucose solution and shaken for 45 min. Each bag was sealed and suspended in 100 ml of distilled water, and then placed in a bath with constant agitation at 37 °C for 4 h. An aliquot of the solution (2 ml) was taken and measured for its glucose concentration via the glucose oxidase method at 0, 10, 20, 30, 60, 120, 150, 180, 210 and 240 min. The GDDC was calculated using the following equation:
For the analysis of the particle size and mean diameter, 100 g of each sample were placed in a stack of 6 U.S. standard sieves 20, 40, 60, 80, 100 and 120 mesh, and placed in a RO-tap shaker (Lab Depot, Dawsonville, GA, USA) for 30 min. The particles retained on each mesh were weighed and the mean particle size diameter (MPD) was determined using the following formula:
Statistical analysis
Data obtained from chemical components (moisture, ash, protein, fat, TDF, IF and SF) and physicochemical properties (WAC, viscosity, GDDC and particle size) were determined in triplicate and analyzed by means of analysis of variance (ANOVA) using the general lineal model procedure. When differences were significant (P < 0.05), the least significant differences (LSD) method was used to evaluate mean value differences, according to the Tukey test. Also, a Cluster Analysis using the Euclidian distances combined with the Ward method was used to identify groups of fibers as a function of their chemical components and physicochemical properties. Afterwards, the identified groups were revised to explain their cluster tendency, and the data obtained from chemical composition and physicochemical properties was analyzed by using the Main Components Analysis method. This allowed the accurate identification of the variables or characteristics that define each group of fibers, as well as the recognition of the relative importance of the characteristics used by the values of their components weights. Finally, a Multiple Correlation Analysis was run to identify the characteristics that are strongly correlated. All the processes were run in the statistical package JMP version 6.0 (SAS Institute Inc. 2005).
Results and discussion
Chemical composition
The chemical composition of the different DF products is shown in . The DS showed a protein content of 22.30%, which was similar to that obtained by Mattila et al. (Citation2002) and by Mizuno (Citation1995), who reported protein values of 21.4% and 22.7%, respectively. However, the major chemical component found in the DS was the TDF with a total of 49.09%, of which 40.70% corresponded to IF and 8.39% to SF. The content of TDF in the DS was similar to that reported by Beelman et al. (Citation2004), who found a value of 47.30%. In the commercial products, the component that predominated was TDF value. For Metamucil, Nopalinaza, Xotzil, Kania and Tarasca products, the values were 52.72%, 33.32%, 21.91%, 50.57% and 33.60%, respectively. The content of TDF was significantly different (P < 0.05) in all fiber products. Also, in Nopalinaza product a high value of protein (26.11%) and fat (35.83%) was observed.
Table 1. Chemical composition (%) of the different products.
Tabla 1. Composición química (%) de los diferentes productos.
Physicochemical properties
The results of the physicochemical properties evaluated in the different fiber products are shown in . Metamucil had the highest WAC value (15.9 g water/g sample) and was statistically different (P < 0.05) compared to the other samples. Tarasca product had the lowest WAC value (1.53 g water/g). Kania and DS had good WAC values, 8.54 and 5.64 g water/g sample, respectively. Chun, Chambers, and Chambers (Citation2005) made pork patties using shiitake mushroom powder as a functional health ingredient and as a good source ingredient of water absorption. They found that mushroom powder may be used as a partial or as a complete replacement for phosphate in the valuated product.
Table 2. Physicochemical properties of the different products.
Tabla 2. Propiedades físico-químicas de los diferentes productos.
On the other hand, the DS had significantly (P < 0.05) the highest OAC value (3.13 g oil/g sample), compared to the other fiber products. Xotzil, Kania, Nopalinaza and Metamucil products had similar values (1.64, 1.52, 1.50, 1.48 g oil/g sample, respectively). With respect to viscosity measurement, Metamucil had the highest value (70.8 cP) which was different (P < 0.05) than the other fiber products. Kania and Nopalinaza products had similar values, 20.7 and 20.4 cP, respectively. The DS, Xotzil and Tarasca products had the lower viscosity values. Viscosity is one of the most important functional characteristics of fibers. Viscosity caused by the fiber prevents complete digestion of foods and reduces uptake of digested products. Also, the fibers bind to cholesterol and fats, inducing their incorporation in mixed micelles and thus their uptake by the body (Venema, Minekus, & Havennar, Citation2004).
In the GDDC measurement (), it was observed that, after 30 min, the smallest quantity of diffused glucose was found in Nopalinaza product (27.6 mg of glucose/dl), Kania (36.5 mg of glucose/dl) and Xotzil (37.8 mg of glucose/dl), and the largest quantity was found in Tarasca product (77.4 mg of glucose/dl). After 60 min, the Nopalinaza product had the lowest value of glucose diffused (45.5 mg of glucose/dl) followed by Kania (64.3 mg of glucose/dl) and Metamucil (64.4 mg of glucose/dl) products. However, Metamucil product had no changes in its glucose diffusion rate after 60 min, and practically the same glucose concentration was found after 30 min (63.8 mg of glucose/dl). At 240 min, Kania, Nopalinaza, Metamucil, and Shiitake products had lower values (79.6, 84.5, 84.5 and 93.4 mg/dl of glucose, respectively) compared to those obtained in Xotzil and Tarasca products (114.9 and 190.4 mg of glucose/dl, respectively).
Figure 1. Glucose diffusion delay capacity of the different fiber products.
Figura 1. Capacidad de retardo de la difusión de glucosa de los diferentes productos de fibra.
Adiotomre et al. (Citation1990) reported that the diffusion of glucose from the lumen to the absorptive cells is aided by the convective activity of the small intestine. However, the glucose absorption decreases in the presence of DF, particularly of the SF fraction. In vitro analysis of the GDDC is important, since it simulates the effect the fibers may have along the gastrointestinal tract. This could be explained because SF had a high WBC. As a SF binds water, a gel is formed, trapping some molecules, such as glucose and lipids; glucose absorption becomes difficult if the intestinal enzyme does not get in contact with the carbohydrates found in the gel matrix, and a delay in the sugar absorption by absorptive cells could occur (Nelson, Citation2001).
The particle size distribution and the mean particle diameter (MPD) are shown in . Metamucil product and the DS show a minor particle size distribution. The latter can be seen when the values of MPD are taken into account. Metamucil product and the DS had MPD values of 169 μm and 202 μm, respectively. The greater MPD values corresponded to Nopalinaza (465 μm) and Xotzil (306 μm) products.
Table 3. Distribution of the particle size (%) and mean particles diameter in different products.
Tabla 3. Distribución del tamaño de partícula (%) y diámetro medio de partícula en los diferentes productos.
Statistical analysis of the data
In , a dendogram is shown, which was obtained by the statistical technique of Ward combined with the Euclidian distances method. It is possible to include the different samples in three different groups, as a function of their chemical composition and their physicochemical properties. In the first group, Metamucil product is clearly identified, being the one with the highest distance with respect to the other samples. The DS appears in the second group, with a behavior similar to Kania product. The third group included Tarasca, Nopalinaza and Xotzil products.
Figure 2. Dendogram of the different fiber products. Shiitake: Dried shiitake mushroom; Kania: Kania product; Nopal: Nopalinaza product; Xotz: Xotzil product; Tarasc: Tarasca product; Meta: Metamucil product.
Figura 2. Dendograma de los diferentes productos de fibra. Shiitake: hongo shhitake deshidratado; Kania: producto Kania; Nopal: Producto Nopalinaza; Xotz: Producto Xotzil; Tarasc: Producto Tarasca; Meta: Prodcuto Metamucil.
With the values obtained from the chemical composition and the physicochemical evaluation of the different samples, the Main Components Analysis test was carried out ( and ) in order to explain the differences obtained from the three groups observed in the dendogram (). In the model used (), the Main Component 1 (MC1), with 41.39% of explained variation, showed high values of SF (0.33630), WAC (0.33877), viscosity (0.32852) and particles size retained on mesh 100 (0.31398), mesh 120 (0.33623) and mesh >120 (0.33681). The main effects (arrow in X axis shows the effect of the components) were observed for the SF, viscosity, WAC, and particles retained on 100, 120 and >120 meshes, and identified more clearly the group conformed by Metamucil product (). On the other hand, in group conformed by DS and Kania products it can be observed, in Y axis, that the main components were related to the IF, OAC, protein and ash contents. Tarasca and Xotzil products showed the lowest TF, SF, WAC and viscosity values as compared to the other products.
Figure 3. Results of Principal Component Analysis on some chemical and physicochemical properties of the different products. SF: soluble fiber; Viscos: viscosity; WAC: water absorption capacity; S 100: particles retained on mesh 100; S 120: particles retained on mesh 120; S > 120: particles that passed through mesh 120; TF: total fiber; IF: insoluble fiber; OAC: oil absorption capacity; GDT30: glucose diffused at 30 min of the test; GDT240: glucose diffused at 240 min of the test.
Figura 3. Resultados del Análisis de Componentes Principales en algunas propiedades químicas y fisicoquímicas de los diferentes productos. SF: fibra soluble; Viscos: viscosidad; WAC: capacidad de absorción de agua; S 100: partículas retenida en malla 100; S 120: partículas retenidas en malla 120; S > 120: partículas menores de 120; TF: fibra total; IF: fibra insoluble; OAC: capacidad de absorción de aceite; GDT30: glucosa difundida a los 30 min del ensayo; GDT240: glucosa difundida a los 240 min del ensayo.
Table 4. Principal Component Analysis on values obtained from different samples.
Tabla 4. Análisis de Componentes Principales en valores obtenidos de las diferentes muestras.
The Multiple Correlation Analysis results are shown in . The SF is highly correlated with the viscosity property (0.9791), and had significant correlations (0.9451) with the WAC characteristic. The SF also had positive correlations with the minor particle size. This effect was associated to the particles retained on mesh No. 120 (0.8628) and mesh > No. 120 (0.8677). The WAC property was positively correlated with the particles retained on meshes No. 100 (0.9009), No. 120 (0.8807) and > No. 120 (0.8821).
Table 5. Correlation Analysis of chemical components and physicochemical properties of different products.
Tabla 5. Análisis de Correlación de los componentes químicos y propiedades físico-químicas de los diferentes productos.
Conclusions
Metamucil product showed the best physicochemical properties, followed by Kania, then dried Shiitake and Nopalinaza samples. These physicochemical properties could be attributed to the presence of the DF, mainly the SF fraction. That was correlated with the WBC and generates high viscosity values.
Related Research Data
References
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