Comparison between collet and cooking extrusions on physicochemical properties of whole grain barley

Research Progress on the Physicochemical Properties of Starch-Based Foods by Extrusion Processing

Extrusion is a crucial food processing technique that involves mixing, heating, shearing, molding, and other operations to modify the structures and properties of food components. As the primary energy source material, the extrusion process induces significant physical and chemical changes in starch that impact the quality of final products. This review paper discusses novel technologies for starch extrusion and their influence on the physical and chemical properties of starch-based foods, such as gelatinization and retrogradation properties, structural characteristics, and digestion properties. Additionally, it examines the application of extrusion in starch processing and the interactions between starch and other food components during extrusion. This information sheds light on the structural and property alterations that occur during the extrusion process to create high-quality starch-based foods.

Individual or mixing extrusion of Tartary buckwheat and adzuki bean: Effect on quality properties and starch digestibility of instant powder

Introduction

Tartary buckwheat and adzuki bean, which are classified as coarse grain, has attracted increasing attention as potential functional ingredient or food source because of their high levels of bioactive components and various health benefits.

Methods

This work investigated the effect of two different extrusion modes including individual extrusion and mixing extrusion on the phytochemical compositions, physicochemical properties and in vitro starch digestibility of instant powder which consists mainly of Tartary buckwheat and adzuki bean flour.

Results

Compared to mixing extrusion, instant powder obtained with individual extrusion retained higher levels of protein, resistant starch, polyphenols, flavonoids and lower gelatinization degree and estimated glycemic index. The α-glucosidase inhibitory activity (35.45%) of the instant powder obtained with individual extrusion was stronger than that obtained with mixing extrusion (26.58%). Lower levels of digestibility (39.65%) and slower digestion rate coefficient (0.25 min^-1) were observed in the instant powder obtained with individual extrusion than in mixing extrusion (50.40%, 0.40 min^-1) by logarithm-of-slope analysis. Moreover, two extrusion modes had no significant impact on the sensory quality of instant powder. Correlation analysis showed that the flavonoids were significantly correlated with physicochemical properties and starch digestibility of the instant powder.

Discussion

These findings suggest that the instant powder obtained with individual extrusion could be used as an ideal functional food resource with anti-diabetic potential.

A review of extrusion-modified underutilized cereal flour: chemical composition, functionality, and its modulation on starchy food quality

Compared with three major cereals, underutilized cereals (UCs) are those with less use but having abundant bioactive components and better functionalities after proper processing. As a productive and energy-efficient technology, extrusion has been used for UC modification to improve its technological and nutritional quality. Extrusion could induce structural and quantitative changes in chemical components of UC flour, the degree of which is affected by extrusion intensity. Based on the predominant component (starch), functionalities of extruded underutilized cereal flour (EUCF) and potential mechanisms are reviewed. Considering bioactive compounds, it also summarizes the physiological functions of EUCF. EUCF incorporation could modulate the dough rheological behavior and starchy foods quality. Controlling extrusion intensity or incorporation level of EUCF is vital to achieve sensory-appealing and nutritious products. This paper gives comprehensive information of EUCF to promote its utilization in novel staple foods.

Effect of Hulless Barley Flours on Dough Rheological Properties, Baking Quality, and Starch Digestibility of Wheat Bread

Hulless barley (Hordeum vulgare L.), also known as highland barley, contains nutritional compounds, such as β-glucan and polyphenol, which can be added to wheat flour to improve the dough nutritional quality. In this study, different formulated dough samples were obtained by individually adding four hulless barley flours into flour of a wheat variety (Jimai 44, designated as JM) which has very strong gluten. The effects of hulless barley supplementation on gluten structure, dough rheological properties, bread-making properties, and starch digestibility were assessed. The results showed that compared with JM dough, substitution of hulless barley flour to wheat flour at levels ranging from 10 to 40% negatively affected gluten micro-structure and dough mixing behavior, because the cross-links of gluten network were partially broken and the dough development time and stability time were shortened. For the hulless barley-supplemented bread, specific volume was significantly (P < 0.05) increased while springiness was not greatly changed. Furthermore, the hydrolysed starch rate in hulless barley-supplemented bread was decreased, compared with that in JM bread. Importantly, the contents of β-glucan, polyphenols and flavonoids in hulless barley-supplemented bread were 132.61-160.87%, 5.71-48.57%, and 25-293.75% higher than those in JM bread, respectively. Taken together, the hulless barley-supplemented bread has been fortified with enhanced nutritional components, more desirable bread-making quality, and improved starch hydrolytic properties, which shows a great potential to use hulless barley as a health supplement.

Physicochemical and Morphological Properties of Extruded Adlay (Coix lachryma-jobi L) Flour

The effects of extrusion treatment on the structure and properties of adlay (Job’s tears) were investigated. Adlay flour was extruded through a twin-screw extruder with different parameters, including barrel temperature (80–160°C), moisture content (19–27%), and screw speed (170–330 rpm). The results showed that although the expansion index increased with increasing temperature, an increase in moisture content significantly decreased the EI (p<0.05). Extrusion improved the water solubility index and water absorption index of adlay flour (p<0.05). Furthermore, analysis of the gelating properties revealed that the structure and function of adlay flour had radically changed. After extrusion, the viscosity of the adlay flour decreased (peak viscosity decreased by more than 1000 cP), and its fluidity increased. The rheological data were modeled by the Herschel–Bulkley model. X-ray diffraction experiments showed that extrusion contributed to a decrease in relative crystallinity. Scanning electron microscopy revealed that extrusion damaged the basic structure of adlay flour, causing holes and pits on the extrudate surface. Compared to the native adlay flour, the extrusion resulted in significantly changing the pasting, gelating, thermal, rheological, and morphological properties of adlay flour. In conclusion, the extrusion can alter adlay characteristics, but it is necessary to choose appropriate conditions to attain the desired properties.