The properties of flours and extrusion characteristics, of three lentil varieties (Brewer, Crimson, and Richlea) were studied. The effects of barrel temperature (110, 125, and 140 °C) and screw speed ...(150, 200, and 250 rpm) on process responses and extrudate characteristics were evaluated using a corotating twin‐screw extruder. The three varieties of lentils had significant differences (p < 0.05) in their starch (48.7% to 50.9%), protein (20.4% to 22.7%), and fat content (1.3% to 1.9%), gelatinization temperature (71.7 to 74.6 °C), peak viscosity (123.3 to 179.7 mPa.s), and melting temperature (113.6 to 119.7 °C). The lentil variety, barrel temperature, and screw speed significantly impacted the process responses and extrudate properties. Whole lentil flours exhibited the highest expansion ratio (3.0 to 3.6) at the lowest temperature (110 °C) and the highest screw speed (250 rpm). Richlea variety had the highest expansion ratio (3.6) and the highest water solubility index (45.4%) as it had the highest starch content and peak viscosity, and the lowest protein content and melting temperature. Meanwhile, Brewer variety exhibited the lowest expansion ratio (1.9 to 3.0) compared to Richlea (2.5 to 3.6) and Crimson (2.4 to 3.0) in most of the extrusion conditions studied. Richlea variety was the most suitable for making direct‐expanded extrudates among the varieties studied. The significant differences in the properties of flours from the three varieties of lentils resulted in significant impacts on the properties of their extrudates. Therefore, determining the properties of flours of different varieties is useful to select the appropriate varieties for extrusion processing.
Practical Application
The information from this study is useful for the food industry to select the appropriate lentil varieties and processing conditions for the development of direct‐expanded products. The data prove the importance of understanding the chemical composition, pasting, and thermal properties to select the appropriate varieties for extrusion processing.
Determining the impacts of extrusion conditions on extrudate characteristics of whole beans flours is critical to find the suitable types of beans to use for making direct expanded products. Whole ...bean flours of four different bean types, faba, lima, pinto, and red kidney, were extruded. The influence of barrel temperature (120, 140, and 160 °C), moisture content (17%, 21%, and 25%), and screw speed (150, 200, and 250 rpm) on process and product responses was studied with a corotating twin screw extruder. The barrel temperature, moisture content, screw speed, and variety of bean had significant influence on process and product responses, back pressure (MPa), torque (N·m), specific mechanical energy (kJ/kg), expansion ratio, water absorption index (g/g), and water solubility index (%) (P < 0.05). Faba bean extrudates had a significantly higher expansion ratio compared to other beans (lima, pinto, and red kidney beans) even though faba bean contained significantly higher protein and higher crude fiber contents (P < 0.05).
Practical Application
The outputs of this research will be helpful to the food industry in the production of high nutrient‐dense food products from whole beans by maintaining the expansion and texture of the products. The data should assist to choose the suitable types of whole bean flours and the optimum processing conditions for making direct expanded extruded products.
Due to their dense characteristics, direct‐expanded products fortified with insoluble fiber are generally not well accepted. Understanding the interactions between starch and fiber could help to ...effectively choose and modify ingredients to produce products containing high amounts of fiber. Therefore, this study aims to explain the interplay between two starches (native and waxy corn) and two pomace types (blueberry and cranberry). Blends up to 100% of pomace were extruded using a co‐rotating twin‐screw extruder. Raw material and milled extrudates were analyzed for their pasting and hydration properties. Fourier‐transform infrared (FTIR) and solid‐state nuclear magnetic resonance (NMR) spectroscopy were conducted to observe molecular changes. The expansion ratio (ER) significantly decreased as pomace was added and ranged from 3.85 for pure waxy corn starch to approximately 1 for blends that contained 80% pomace. Distinctions between the blends were observed. Particularly, at 20% of pomace inclusion, native corn starch with cranberry pomace showed a significantly higher ER. Different behaviors were also detected during the physicochemical analyses. A nonlinear trend between pomace level and water solubility as well as absorption was observed for native corn starch blends, suggesting that molecular interactions between the biopolymers occur. FTIR and NMR results give no evidence for new covalent bonds; hence, the most likely interactions occurring are hydrogen bonds. In addition to the dilution effect of pomace addition, the enhancement or weakening of such interactions between starch molecules by pomace compounds may reduce the ER.
Ten novel breeding lines of quinoa (Chenopodium quinoa Willd) suitable to be grown in the Pacific Northwest of the United States were developed and utilized for extrusion processing. Understanding ...how a particular breeding line performs during food processing and which properties determine its performance can promote the use of quinoa as an ingredient in value‐added products, such as extruded snacks. In this study, extrusion characteristics of the whole seed flours of the novel quinoa breeding lines were evaluated using a co‐rotating twin‐screw extruder at two temperatures (110°C and 125°C), three screw speeds (200, 350, and 500 rpm), and a moisture content of 18% (w.b.). The expansion ratio (ER) ranged from 1.15 to 2.33 and was negatively influenced by the fat content in the flours. Breeding line 11WAQ‐104.88 (WAQ10) exhibited the greatest potential for use in direct expanded foods as it had the highest ER for all conditions studied. Strong correlations were found between ER and pasting properties of the flours, proving the usefulness of the pasting test for flour quality evaluation before extrusion processing. The results demonstrate the potential of using quinoa for producing direct expanded food products and highlight the importance of selecting specific breeding lines for desired product characteristics.
Practical Application
This study provides the extrusion processing characteristics of 10 new quinoa breeding lines. Based on the information gained, it will be easier for the food industry, including breeders as well as processors, to select the right quinoa variety based on their requirements, and may further help to enhance the use of quinoa.
Expansion characteristics of cornstarch‐based extrudates incorporating fiber‐rich food processing byproducts was explored. Waxy and regular cornstarch were used as the base materials with apple ...pomace and sugarcane bagasse incorporated at two addition levels (0%, 15%, and 30% w/w). Extrusions were conducted at three different screw speeds (150, 200, and 250 rpm) with other parameters optimized and kept constant. Apple pomace inclusion resulted in higher initial expansion index (4.23 to 5.60) and higher stable expansion index (2.76 to 4.43), but also showed higher shrinkage (8.50% to 34.72%) than sugarcane bagasse extrudates at the same inclusion levels. Inclusion of apple pomace showed potential of producing extrudates with significantly higher expansion than cornstarch control, with relatively lower energy inputs. Extrusion methods used here have the potential to preserve the textural quality and nutritional value of the fiber‐enriched extrudates, providing the base for healthier snack food items.
Practical Application
Findings from this study can be extended to the other fiber‐rich food processing byproducts, such as other fruit and vegetable pomace, cereal brans, and pulse hulls among other materials. This data will help the development of fiber‐enriched extruded snacks that would have favorable consumer traits.
Extrusion processing characteristics of pea starch were studied as impacted by various extrusion cooking processing variables, including, moisture content (15%, 17.5%, and 20% w.b.), temperature ...(120, 135, and 150 °C), and screw speed (150, 200, and 250 rpm), in a co‐rotating twin‐screw extruder. Physicochemical properties such as radial expansion ratio (ER), unit density (UD), water absorption index (WAI), and water solubility index (WSI) were measured. ER of the extrudates ranged between 2.52 and 3.63. These values of ER were significantly high, although relatively lower compared to the highest values reported in the literature for corn and rice extrudates. The UD values for all the extrudates ranged from 0.12 to 0.35 g/cm3, WAI, and WSI values ranged from 10.98 to 12.10 g/g and from 0.12% to 7.73%, respectively. Both screw speed and moisture content had significant impacts on the ER (P < 0.01). The highest ER was observed for the extrusion cooking conditions of the lowest moisture content level (15%), lowest barrel temperature (120 °C), and lowest screw speed (150 rpm). The cross‐sectional microstructure of the extrudates showed that the samples with a high ER had thick and elongated pores. The results of this study indicate that pea starch is a viable ingredient for making puffed extruded products.
Practical Application
The food industry can utilize the information generated from this study in the development of extruded expanded food products with pea starch. The specific information related to process conditions can assist the food industry in determining the ideal conditions for extrusion cooking in the production.
The inclusion of cellulose nanocrystals (CNC) and microcrystalline cellulose (MCC) during extrusion processing of corn starch (CS) is presented in this study. Blends were prepared by incorporating ...CNC and MCC at different concentrations, 1%, 3%, 5%, and 10% w/w in CS. The crystallinity index (CrI) of CNC and MCC was determined using X‐ray diffraction, and the chemical functionality of CNC, MCC, and CS was studied using Fourier transform infrared spectroscopy. The pasting properties of the blends were studied using Micro Visco‐Amylo‐Graph before extrusion. The blends were preconditioned to 18 ± 0.5% (w.b.) moisture and extruded using a twin‐screw extruder at 200 and 250 rpm at 140°C. CS‐CNC's expansion ratio (ER) values were 2.95 to 3.35 and 2.72 to 3.22 for MCC. CNC's CrI and particle size were significantly lower than MCC, allowing CNC‐based extrudates to have ER values similar to the control even at high CNC concentration (≤10% w/w). This study demonstrated that fiber with particle size <100 µm can be added in direct‐expanded product formulations at high concentrations without negatively influencing the extrudate texture while offering increased nutritional value.
Practical Application
This study gives insight into the potential application of cellulose nanocrystals and microcrystalline cellulose in manufacturing direct‐expanded extruded products, providing high fiber content without compromising the product quality. This knowledge could also be translated into manufacturing other food products such as breakfast cereals, pasta, and bread.
Nuña bean, also known as “popping” bean, belongs to the group of common beans (Phaseolus vulgaris, L.). Originated in Andean mountains, nuña beans is an important food crop in several South American ...countries, including Bolivia, Ecuador, and Peru, where it is consumed primarily as a snack. Nuña beans are highly nutritious and have a distinctive nutty flavor, which makes them potentially desirable ingredients in food applications, such as extruded snacks. Thus, the goal of this study was to evaluate the performance of whole seed nuña bean flour during extrusion cooking. Expansion characteristics of whole nuña bean flour were investigated using a twin‐screw extruder. Three levels of moisture contents of 15%, 18%, and 21% (wet basis), three barrel temperatures of 120, 140, and 160 °C, and three screw speeds of 150, 200, and 250 rpm were evaluated, with a die diameter of 3.15 mm. The expansion ratio (ER) ranged from 1.41 to 3.03, within the extrusion conditions studied. The moisture content and screw speed were found to have the most significant impact on the ER. Lower temperature and higher screw speed resulted in higher ER. The maximum ER of 3.03 was observed at a moisture content of 15%, a barrel temperature of 120 °C, and a screw speed of 250 rpm. Nuña bean flour exhibited good expansion properties at relatively low temperatures, which highlights its potential for use in extruded food applications such as nutritious snacks.
Practical Application
There is increasing consumer demand for more nutritional snacks and cereals. Nuña bean flour exhibited potential for use in such nutritious products. This provides the industry with an alternative source of protein and fiber for inclusion in expanded food products.
•Amorphization mechanisms for desirable material characteristics.•Extrusion integration for highly hydrolysable substrates.•Novel stepwise pulverization process for cost-effective clean fermentable ...sugars.
Thermo-chemical pretreatments of biomass typically result in environmental impacts from water use and emission. The degradation byproducts in the resulting sugars can be inhibitory to the activities of enzymes and yeasts. The results of this study showed that combining existing commercial comminution technology can reduce total energy consumption with improved saccharification yield while eliminating chemical use. Impact mill was found to be the most efficient milling for size reduction of forest residual chips from ca. 2 mm to a specific value below 100 µm. The further micronization effectively disrupted the recalcitrance of the woody biomass and produced the highly saccharifiable substrates for downstream processing. In addition, extrusion can be integrated into a clean cellulosic sugar process for further fibrillation in place of the conventional mixing processing. The highest energy efficiency was observed on the impact-milled samples with 0.515 kg sugars kWh−1.
The processing of agricultural products into value-added food products yields numerous by-products or waste streams such as pomace (fruit and vegetable processing), hull/bran (grain milling), ...meal/cake (oil extraction), bagasse (sugar processing), brewer's spent grain (brewing), cottonseed meal (cotton processing), among others. In the past, significant work in exploring the possibility of the utilization of these by-products has been performed. Most by-products are highly nutritious and can be excellent low-cost sources of dietary fiber, proteins, and bioactive compounds such as polyphenols, antioxidants, and vitamins. The amount of energy utilized for the disposal of these materials is far less than the energy required for the purification of these materials for valorization. Thus, in many cases, these materials go to waste or landfill. Studies have been conducted to incorporate the by-products into different foods in order to promote their utilization and tackle their environmental impacts. Extrusion processing can be an excellent avenue for the utilization of these by-products in foods. Extrusion is a widely used thermo-mechanical process due to its versatility, flexibility, high production rate, low cost, and energy efficiency. Extruded products such as direct-expanded products, breakfast cereals, and pasta have been developed by researchers using agricultural by-products. The different by-products have a wide range of characteristics in terms of chemical composition and functional properties, affecting the final products in extrusion processing. For the practical applications of these by-products in extrusion, it is crucial to understand their impacts on the qualities of raw material blends and extruded products. This review summarizes the general differences in the properties of food by-products from different sources (proximate compositions, physicochemical properties, and functional properties) and how these properties and the extrusion processing conditions influence the product characteristics. The discussion of the by-product properties and their impacts on the extrudates and their nutritional profile can be useful for food manufacturers and researchers to expand their applications. The gaps in the literature have been highlighted for further research and better utilization of by-products with extrusion processing.
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