Synthesis of novel α-glucans with potential health benefits through controlled glucose release in the human gastrointestinal tract

The glycemic carbohydrates we consume are currently viewed in an unfavorable light in both the consumer and medical research worlds. In significant part, these carbohydrates, mainly starch and sucrose, are looked upon negatively due to their rapid and abrupt glucose delivery to the body which causes a high glycemic response. However, dietary carbohydrates which are digested and release glucose in a slow manner are recognized as providing health benefits. Slow digestion of glycemic carbohydrates can be caused by several factors, including food matrix effect which impedes α-amylase access to substrate, or partial inhibition by plant secondary metabolites such as phenolic compounds. Differences in digestion rate of these carbohydrates may also be due to their specific structures (e.g. variations in degree of branching and/or glycosidic linkages present). In recent years, much has been learned about the synthesis and digestion kinetics of novel α-glucans (i.e. small oligosaccharides or larger polysaccharides based on glucose units linked in different positions by α-bonds). It is the synthesis and digestion of such structures that is the subject of this review

Development of a rapid screening method for improved breeder popcorn lines

For microwaveable popcorn, quality is of great importance. Quality can be improved by developing popcorn breeding lines. However, breeding programs have a small amount of material and need nondestructive analytical methods. The objective was to develop a nondestructive method for selection of breeding material. The following baseline information was determined for 18 popcorn lines: number of kernels per 10g, density, Stenvert hardness, pericarp thickness, moisture loss, and total starch content. Finally, correlations between popping performance and the baseline information were computed. Significant differences were found among samples for popping performance and all sample characteristics. Samples with high expansion volume had generally greater flake sizes, lower number of kernels/10 g, lower kernel density and lower Stenvert hardness values. Pericarp thickness did not appear to be related to popping performance. Moisture loss during microwave heating correlated significantly (r = 0.76) with percentage of unpopped kernels, indicating that the number of unpopped kernels increased as a greater amount of moisture was lost during microwave heating. With regard to total starch content, samples with high expansion volume and large kernel size had the highest starch content. Total starch content had weak but significant correlations with number of kernels/10g (r = -0.64), and flake size (r = 0.59). Number of kernels/10g and flake size were significantly and negatively correlated with each other (r = -0.77). Predictive correlations were not observed between physical and chemical traits and popping performance. It was difficult to find predictive relationships due to the narrow range of the sample traits. Expansion volume was used for developing a model with near-infrared spectroscopy (NIRS). A total of 128 samples were used and models were calibrated with different combinations of the samples. A model calibrated with 84 popcorn samples at equilibrium moisture content (13.5-14%) resulted in a cross validation R 2 = 0.56 and a RMSECV = 2.16. When the model was tested with an analysis of unknown samples, it accurately predicted expansion volume of new samples; especially samples with expansion volume greater than 50 cc/g. However, more work is needed to improve the NIRS model and the accuracy of predicting popcorn expansion volume

Efecto de la temperatura de enfriamiento y formulación en la elaboración de Dulce de Leche

38 p.Lamothe, L. 2006. Efecto de la temperatura de enfriamiento y formulación en la elaboración de dulce de leche. Proyecto de Graduación del Programa de Ingeniería en Agroindustria Alimentaria, Escuela Agrícola Panamericana, El Zamorano, Honduras. 38 p. La temperatura de enfriamiento afecta la formación y el tamaño de los cristales de lactosa. Una práctica común para evitar la formación de estos cristales es el uso de β-D-galactosidasa en la elaboración de dulce de leche. El objetivo principal del estudio fue evaluar el efecto de dos formulaciones y dos temperaturas de enfriamiento que retrasen la formación de cristales de lactosa en el producto final. Se utilizó un arreglo factorial con diseño de bloques completos al azar y con medidas repetidas en el tiempo. Se evaluó cada formulación y temperatura de enfriamiento (4 °C y -10 °C) al alcanzar 72 °Brix. La formulación A incluyó crema al 40%, LDP, azúcar y agua. La formulación B incluyó leche entera al 3.8% y azúcar. A ambas formulaciones se les agregó β-D-galactosidasa utilizando una concentración de 2.2 ml/L (Maxilact). La formación de cristales de lactosa y atributos sensoriales como color, dulzura y aceptación general del producto fueron evaluados a los días cero, quince y treinta. Asimismo se evaluaron características físico-químicas como color, viscosidad y se realizó un análisis proximal de los dos tratamientos que presentaron menor cristalización y mayor aceptación. Los cristales de lactosa fueron percibidos a partir del día quince para todos los tratamientos siendo los tratamientos de la formulación A los que presentaron menor cristalización (P<0.05). Estos tratamientos obtuvieron la mejor evaluación en aceptación general con promedios de 3.69 y 3.59 (P<0.05). La formulación A tuvo un menor desarrollo de cristales de lactosa. Entre los tratamientos de esta misma formulación, el que fue enfriado a -10 °C tuvo una menor cantidad y tamaño de cristales (P<0.05). El aumento en el porcentaje de grasa láctea y sólidos totales de la formulación A originó una cantidad y tamaño menor de cristales de lactosa (P<0.05).1. Índice de cuadros 2. Índice de figuras 3. Índice de anexos 4. Revisión de literatura 5. Introducción 6. Materiales y métodos 7. Resultados y discusión 8. Conclusiones 9. Recomendaciones 10. Bibliografía 11. Anexo

The Effect of Arabinoxylan and Wheat Bran Incorporation on Dough Rheology and Thermal Processing of Rotary-Moulded Biscuits

Wheat bran incorporation into biscuits may increase their nutritional value, however, it may affect dough rheology and baking performance, due to the effect of bran particles on dough structure and an increase in water absorption. This study analyzed the enrichment effect of wheat bran and arabinoxylans, the most important non-starch polysaccharides found in whole wheat flour, on dough rheology and thermal behaviour during processing of rotary-moulded biscuits. The objective was to understand the contribution of arabinoxylans during biscuit-making and their impact when incorporated as wheat bran. Refined flour was replaced at 25, 50, 75, or 100% by whole flour with different bran particle sizes (fine: 4% &gt; 500 μm; coarse: 72% &gt; 500 μm). The isolated effect of arabinoxylans was examined by preparing model flours, where refined flour was enriched with water-extractable and water-unextractable arabinoxylans. Wheat bran had the greatest impact on dough firmness and arabinoxylans had the greatest impact on the elastic response. The degree of starch gelatinization increased from 24 to 36% in biscuits enriched with arabinoxylans or whole flour and coarse bran. The microstructural analysis (SEM, micro-CT) suggested that fibre micropores may retain water inside their capillaries which can be released in a controlled manner during baking

Changing Wheat Bran Structural Properties by Extrusion-Cooking on a Pilot and Industrial Scale: A Comparative Study

Extrusion-cooking can be used to change the techno–functional and nutrition-related properties of wheat bran. In this study, pilot-scale (BC21) and industrial-scale (BC45) twin-screw extrusion-cooking using different types of extrusion (single-pass, double-pass and acid extrusion-cooking) and process parameters (temperature, moisture) were compared for their impact on wheat bran. When applying the same process settings, the higher strong water-binding capacity, extract viscosity and extractability displayed by bran extruded using the industrial set-up reflected a more considerable wheat bran structure degradation compared to pilot-scale extrusion-cooking. This was attributed to the overall higher specific mechanical energy (SME), pressure and product temperature that were reached inside the industrial extruder. When changing the type of extrusion-cooking from single-pass to double-pass and acid extrusion-cooking, wheat bran physicochemical characteristics evolved in the same direction, irrespective of extruder scale. The differences in bran characteristics were, however, smaller on industrial-scale. Results show that the differentiating power of the latter can be increased by decreasing the moisture content and increasing product temperature, beyond what is possible in the pilot-scale extruder. This was confirmed by using a BC72 industrial-scale extruder at low moisture content. In conclusion, the extruder scale mainly determines the SME that can be reached and determines the potential to modify wheat bran

The Effect of Wet Milling and Cryogenic Milling on the Structure and Physicochemical Properties of Wheat Bran

Wheat bran consumption is associated with several health benefits, but its incorporation into food products remains low because of sensory and technofunctional issues. Besides, its full beneficial potential is probably not achieved because of its recalcitrant nature and inaccessible structure. Particle size reduction can affect both technofunctional and nutrition-related properties. Therefore, in this study, wet milling and cryogenic milling, two techniques that showed potential for extreme particle size reduction, were used. The effect of the milling techniques, performed on laboratory and large scale, was evaluated on the structure and physicochemical properties of wheat bran. With a median particle size (d(50)) of 6 mu m, the smallest particle size was achieved with cryogenic milling on a laboratory scale. Cryogenic milling on a large scale and wet milling on laboratory and large scale resulted in a particle size reduction to a d(50) of 28-38 mu m. In the milled samples, the wheat bran structure was broken down, and almost all cells were opened. Wet milling on laboratory and large scale resulted in bran with a more porous structure, a larger surface area and a higher capacity for binding water compared to cryogenic milling on a large scale. The extensive particle size reduction by cryogenic milling on a laboratory scale resulted in wheat bran with the highest surface area and strong water retention capacity. Endogenous enzyme activity and mechanical breakdown during the different milling procedures resulted in different extents of breakdown of starch, sucrose, beta-glucan, arabinoxylan and phytate. Therefore, the diverse impact of the milling techniques on the physicochemical properties of wheat bran could be used to target different technofunctional and health-related properties

Micronutrient Profile and Carbohydrate Microstructure of Commercially Prepared and Home Prepared Infant Fruit and Vegetable Purees

Large variability exists in ingredient selection and preparation of home prepared infant purees and there is a lack of data on nutritional quality in comparison to commercially prepared purees. This work had two aims. Study 1 compared the nutritional value of commercially prepared and home prepared infant purees. Food profiles from national food composition databases were used as a proxy for home prepared puree and served as the benchmark for the commercially prepared infant purees. Study 2 focused on a subset of produce that underwent molecular weight analysis to determine differences in carbohydrate profiles. Eighty-eight percent of the measurable micronutrients fell within or above the home prepared norm range with micronutrients falling below the range explained by differences in soil and growing conditions. Physicochemical characterization showed similar carbohydrate profiles with >90% of the carbohydrate fraction in the water extract constituted by low molecular weight sugars for purees produced with home preparation and commercial preparation. The estimated glycemic load (eGL) showed comparable potential impact on blood sugar levels with all purees having a low eGL (<10 glucose equivalent). In conclusion, these data suggest that both preparations provide similar micronutrient density and carbohydrate profiles

Process-Induced Changes in the Quantity and Characteristics of Grain Dietary Fiber

Daily use of wholegrain foods is generally recommended due to strong epidemiological evidence of reduced risk of chronic diseases. Cereal grains, especially the bran part, have a high content of dietary fiber (DF). Cereal DF is an umbrella concept of heterogeneous polysaccharides of variable chemical composition and molecular weight, which are combined in a complex network in cereal cell walls. Cereal DF and its distinct components influence food digestion throughout the gastrointestinal tract and influence nutrient absorption and other physiological reactions. After repeated consumption of especially whole grain cereal foods, these effects manifest in well-demonstrated health benefits. As cereal DF is always consumed in the form of processed cereal food, it is important to know the effects of processing on DF to understand, safeguard and maximize these health effects. Endogenous and microbial enzymes, heat and mechanical energy during germination, fermentation, baking and extrusion destructurize the food and DF matrix and affect the quantity and properties of grain DF components: arabinoxylans (AX), beta-glucans, fructans and resistant starch (RS). Depolymerization is the most common change, leading to solubilization and loss of viscosity of DF polymers, which influences postprandial responses to food. Extensive hydrolysis may also remove oligosaccharides and change the colonic fermentability of DF. On the other hand, aggregation may also occur, leading to an increased amount of insoluble DF and the formation of RS. To understand the structure–function relationship of DF and to develop foods with targeted physiological benefits, it is important to invest in thorough characterization of DF present in processed cereal foods. Such understanding also demands collaborative work between food and nutritional sciences

Process-Induced Changes in the Quantity and Characteristics of Grain Dietary Fiber

Daily use of wholegrain foods is generally recommended due to strong epidemiological evidence of reduced risk of chronic diseases. Cereal grains, especially the bran part, have a high content of dietary fiber (DF). Cereal DF is an umbrella concept of heterogeneous polysaccharides of variable chemical composition and molecular weight, which are combined in a complex network in cereal cell walls. Cereal DF and its distinct components influence food digestion throughout the gastrointestinal tract and influence nutrient absorption and other physiological reactions. After repeated consumption of especially whole grain cereal foods, these effects manifest in well-demonstrated health benefits. As cereal DF is always consumed in the form of processed cereal food, it is important to know the effects of processing on DF to understand, safeguard and maximize these health effects. Endogenous and microbial enzymes, heat and mechanical energy during germination, fermentation, baking and extrusion destructurize the food and DF matrix and affect the quantity and properties of grain DF components: arabinoxylans (AX), beta-glucans, fructans and resistant starch (RS). Depolymerization is the most common change, leading to solubilization and loss of viscosity of DF polymers, which influences postprandial responses to food. Extensive hydrolysis may also remove oligosaccharides and change the colonic fermentability of DF. On the other hand, aggregation may also occur, leading to an increased amount of insoluble DF and the formation of RS. To understand the structure–function relationship of DF and to develop foods with targeted physiological benefits, it is important to invest in thorough characterization of DF present in processed cereal foods. Such understanding also demands collaborative work between food and nutritional sciences