Effect of extrusion processing on physicochemical, functional and nutritional characteristics of rice and rice-based products: A review

Understanding the deterioration of fresh brown rice noodles from the macro and micro perspectives

The microbial compositions, quality characteristics, and structural changes in fresh brown rice noodles (FBRN) during storage were investigated. Total plate count and mold and yeast counts increased while the pH decreased during storage. Metagenomic sequencing revealed that the microbial composition of FBRN changed throughout storage. A comprehensive investigation of the variation in lipid content demonstrated that hydrolytic rancidity was responsible for lipid deterioration. LF-NMR showed an increase in the proportion of bound water and a decrease in the proportion of free water in FBRN. Moreover, significant changes in edible qualities were observed. The cooking loss increased three-fold and noodles hardness reduced by approximately 23%. Further, the high initial aldehyde content of FBRN diminished almost completely, while that of alcohols and esters increased, leading to significant flavor deterioration. The correlation and factor analysis suggested that the TPC and MY counts could be used as key indicators of FBRN deterioration.

Considerations for improvising fortified extruded rice products

Micronutrient fortification of rice by extrusion is an effective strategy to enhance micronutrient levels within rice-consuming individuals. The success of extrusion-based fortification is associated with micronutrient retention, enhanced bioavailability, low postprocessing losses, prolonged storage stability, and minimal sensory changes. The success of an optimally fortified product is primarily reliant upon the compositional considerations, but many attributes of extrudates can be indebted to the processing parameters too. Hence, an exhaustive investigation of this technology has been taken-up here, emphasizing on the compositional parameters in association with process parameters, which influence the final quality attributes like nutrient stability, bioavailability, and sensory properties. Based on these attributes of the end product, a collected data have been presented here to bring out the optimal compositional requirements. These together with cooking processes, extrusion process parameters, and storage conditions will enable formulate a product with enhanced sensory acceptance, better retention during cooking and storage, improved texture, and acceptable color. This review will thus help to optimize a need-based product, its quality, and enhance benefits of fortified extruded rice products.

Impact of Extrusion Temperature on In Vitro Digestibility and Pasting Properties of Pea Flour

Pea flour was extruded at 50, 70, and 90 °C. The in vitro digestibility and characteristics of native and extruded pea flour were investigated. The in vitro starch digestibility (IVSD) and in vitro protein digestibility (IVPD) of the extruded pea flour were higher than those of the native pea flour and increased with increasing extrusion temperature from 50 to 90 °C. The rapidly digestible starch increased to 28.34% at 90 °C, the highest slowly digestible starch (SDS) content was 22.70% at 50 °C, and resistant starch content decreased to 4.71% at 90 °C. The IVPD increased from 80.94% relative to the native pea flour to 90.21% at 90 °C. Improved swelling power enabled the extruded pea flour to exhibit better performance and higher breakdown viscosity and lower setback viscosity than the native pea flour demonstrated that extrusion reduced the thermal stability and retrogradation tendency. Increasing extrusion temperatures greatly reduced the relative crystallinity (based on X-ray diffraction analysis) from 32.69% relative to the native pea flour to 9.76% at 90 °C. Extrusion treatment also reduced β-sheet content (based on Fourier transform infrared spectroscopy analysis) from 36.40% relative to the native pea flour to 31.79% at 90 °C. IVPD and IVSD improved, and the SDS content increased at 50 °C and 70 °C, thereby indicating that extruded pea flour can be applied to healthy food products.

Autoclaved and Extruded Legumes as a Source of Bioactive Phytochemicals: A Review

Legumes have been consumed since ancient times all over the world due to their easy cultivation and availability as a low-cost food. Nowadays, it is well known that pulses are also a good source of bioactive phytochemicals that play an important role in the health and well-being of humans. Pulses are mainly consumed after processing to soften cotyledons and to improve their nutritive and sensorial characteristics. However, processing affects not only their nutritive constituents, but also their bioactive compounds. The final content of phytochemicals depends on the pulse type and variety, the processing method and their parameters (mainly temperature and time), the food matrix structure and the chemical nature of each phytochemical. This review focuses on the changes produced in the bioactive-compound content of pulses processed by a traditional processing method like cooking (with or without pressure) or by an industrial processing technique like extrusion, which is widely used in the food industry to develop new food products with pulse flours as ingredients. In particular, the effect of processing methods on inositol phosphates, galactosides, protease inhibitors and phenolic-compound content is highlighted in order to ascertain their content in processed pulses or pulse-based products as a source of healthy phytochemicals.

Berrios J. Tiger Nut (Cyperus esculentus) as a Functional Ingredient in Gluten-Free Extruded Snacks

Tiger nut (TN) is a nutritious source of gluten-free flour, used generally in healthy beverages, but its incorporation in gluten-free extruded snacks has not been explored. TN flour was blended at different concentrations (up to 70%) with rice flour and soluble fiber, for the development of gluten-free snacks on a twin-screw extruder. The effect of TN inclusion in the formulations was evaluated on relevant physiochemical characteristics of the snacks. Viscoamylograph of the raw formulations showed that TN addition increased (p < 0.01) onset temperature and delayed peak viscosity. In the extruded flours, TN contributed to limit the starch degradation during extrusion. Diameter, expansion ratio, true density, and total pore volume of the extrudates were reduced (pf < 0.01) by the increased TN content in the formulations, while bulk density rose. The surfaces of the extruded snacks were modified by the increasing inclusion of TN in substitution of rice in the formulations. Extrudates containing 10% TN showed the best overall texture profile. Moreover, TN addition enhanced the ash and protein content of the snacks and increased their total antioxidant activity. This study demonstrated that incorporation of 10% TN flour into rice-based formulation was suitable for making gluten-free snacks with acceptable physical properties.

Effect of extrusion temperature on the protein aggregation of wheat gluten with the addition of peanut oil during extrusion

The influence of extrusion temperature on protein components and aggregation of wheat gluten (WG) and wheat gluten-peanut oil complexes (WPE) during extrusion with the addition of peanut oil was studied. Gliadin content and wheat gluten extractability decreased and glutenin content increased as extrusion temperature increased. At the same extrusion temperature, the gliadin content in WPE was higher than that in WG. The addition of peanut oil also resulted in the higher gluten extractability of WPE than WG. Increasing extrusion temperature also increased the average molecular weight of glutenin and gliadin. The decreased free sulfhydryl (SH) and increased disulfide bonds (SS) indicated that wheat gluten aggregation was promoted, via disulfide cross-linking, when extrusion temperature increased. Furthermore, increased temperature promoted the aggregation of gluten by increasing sulfhydryl-disulfide bond (SH-SS) interchange during extrusion. When the secondary structure of wheat gluten was analyzed by circular dichroism, the relative gluten α-helix content was decreased and the relative β-sheet content was increased. Also, the results of scanning electron microscopy (SEM) showed the size of the resultant particles increased with temperature, and the mean particle size of WPE was higher than WG. This research shows that extrusion temperature promotes gluten aggregation of WG and WPE. It provides basic data to support the study of gluten-lipid extrusion in the field of protein processing.

Investigation on mild extrusion cooking for development of snacks using rice and chickpea flour blends

A study was conducted to optimize the mild extrusion cooking conditions for development of rice and chickpea based extrudates. The independent variables i.e. extrusion parameters (Screw speed, barrel temperature), feed moisture and proportions of rice flour and chickpea flour were varied using central composite rotatable design (CCRD), and their effects on system parameter- Specific mechanical energy (SME) and product characteristics i.e., water absorption index (WAI), water solubility index (WSI), bulk density (BD), expansion ratio (ER), breaking strength (BS), colour values (L*, a* and b*) and overall acceptability (OA) were studied. All the system and product responses were significantly affected by independent variables. Response surface and regression models were established to determine the responses as function of process variables. Models obtained were highly significant with high coefficient of determination (R² ≥ 0.889). The optimum mild extrusion conditions obtained by numerical optimization for development of snacks were 102 °C barrel temperature, 281 rpm screw speed, 18.3% feed moisture and rice to chickpea flour ratio as 90:10. Storage studies confirmed that the developed snacks can be stored better in laminated pouches than in high density polyethylene (HDPE) bags for a period of 6 months under ambient conditions.

Exploring the physicochemical and cooking properties of some Indian aromatic and non-aromatic rice (Oryza sativa L.) cultivars

The objective of the present investigation was to assess the physicochemical and cooking properties of Indian rice cultivars grown locally by farmers. Results reported the highest hulling (80.82%) and milling (75.47%) in cultivar Badshah Bhog (BSB) while the head rice out-turns were maximum in Govind Bhog (GVB) (58.22%) and broken rice was minimum in Khushboo (KSB) (5.15%). The kernel length (6.16-7.88 mm) of KSB, Kalanamak (KLN), Sarbati (SRB) and Todal (TDL) cultivars were nearly alike to the preferred minimum acceptable standard of Basmati rice (6.6mm). The kernel and volume elongation ratio was highest in Swetganga (STG) (2.07) and TDL (4.07), respectively whereas the amylose content was highest (>20%) in all aromatic cultivars and categorized the intermediate type than evolved aromatic rice KLN and nonaromatic cultivars (SRB and TDL). Further, the studied rice cultivars had grain quality characteristics similar to the minimum acceptable standards for the breeding of basmati type cultivars which may be employed for breeding purposes and can be graded as export quality rice possessing distinct nutritional values at the global level.

Effects of rice straw structure on chaetoglobosin A production by Chaetomium globosum CGMCC 6882

As the most abundant macromolecules in nature, lignocelluloses are served as a promising and renewable source for sustainable production of high value chemical compounds. In present work, extrusion pretreatment with 23% (w/w) distilled water, 2% (w/w) glycerol and 1 g/L NaHCO₃ as moisture agent, not only reduced the particle size, crystallinity and component contents (cellulose, hemicelluloses and lignin) of rice straw, but also effectively enhanced chaetoglobosin A yield and degradation rate of rice straw by C. globosum CGMCC 6882. Meanwhile, mycelial biomass of C. globosum CGMCC 6882 increased from 2.9 g/L to 7.0 g/L, mycelia growth time reduced by 2 days and chaetoglobosin A titer increased from 108.4 mg/L to 270.2 mg/L, representing an increase of 149.3%. Furthermore, degradation rate of rice straw by C. globosum CGMCC 6882 increased from 28.93% to 65.38%. This work provides a good guidance for production of chaetoglobosin A from lignocelluloses.

Dynamic Change of Polymer in Rice Analogues and Its Effect on Texture Quality

Macromolecules will leach from the inside of rice analogues (RA) to the external environment and form escaping substances (ES) when boiling in water for a long time. Some escaped substances adhere to the surface of cooked rice analogues (CRA) to form an adhesive layer (AL), which has an important impact on the cooking quality of RA. In this study, hydrocolloids and emulsifier were added and formed RA. Physicochemical, structural, and textural properties of ES, AL, and CRA samples were analyzed to study the effect of hydrocolloids on cooking quality of RA. The results showed that SA inhibited the leach of molecules, reduced MW of AL, decreased starch content of ES and AL, decreased shear viscosity of RA, and enhanced hydrogen bonding interactions. Ca2+ increased the dry matter content of CRA and AL, enhanced hydrogen bonding interactions of ES and CRA, and decreased MW of ES. Textural property results showed that the gelatinous properties of RA were enhanced after SA was added. The Ca2+ in the solution increased the adhesiveness of RA, while decreasing their elasticity. This study explained how hydrocolloids affect the texture properties of RA at a molecular level.

Application of extrusion technology in plant food processing byproducts: An overview

The food processing industry generates an immense amount of waste, which leads to major concerns for its environmental impact. However, most of these wastes, such as plant-derived byproducts, are still nutritionally adequate for use in food manufacturing. Extrusion is one of the most versatile and commercially successful processing technologies, with its widespread applications in the production of pasta, snacks, crackers, and meat analogues. It allows a high degree of user control over the processing parameters that significantly alters the quality of final products. This review features the past research on manufacture of extruded foods with integration of various plant food processing byproducts. The impact of extrusion parameters and adding various byproducts on the nutritional, physicochemical, sensory, and microbiological properties of food products are comprehensively discussed. This paper also provides fundamental knowledge and practical techniques for food manufacturers and researchers on the extrusion processing of plant food byproducts, which may increase economical return to the industry and reduce the environmental impact.

Production of innovative gluten-free breakfast cereals based on red and black rice by extrusion processing technology

The transformation of black and red, broken or not, whole rice grains, into breakfast cereals is an interesting way to add value to these snacks for some reasons. Firstly, broken kernels hardly achieve a high market value; whole rice is healthy not only for their nutrient contents but also for their phytochemical profile, rich in phenolic compounds; breakfast cereals from pigmented rice are colored by themselves, and any additional colorant is unneeded; finally, rice is naturally gluten-free and suitable for those with conditions like celiac disease or gluten sensitivity. The objective of this study was to optimize some extrusion parameters that account for the physicochemical properties of extrudates by using response surface methodology. Feed moisture between 15 and 21% and the 4th barrel zone temperature between 110 and 160 °C were the independent variables. Specific features such as color, texture, water solubility and absorption, cold viscosity, expansion, specific volume, and compression force were evaluated. The trials have shown that moisture had a higher impact on the extrusion process than temperature. Less expanded, denser, harder, and darker products were obtained at higher moisture levels. The optimum points were defined at 15.5% and 16.0% of feed moisture and 159 °C and 150 °C of temperature for black and red rice extrudates, respectively. These conditions resulted in cereal breakfast balls with optimal water solubility, volume, texture, and good color. Additionally, cold viscosities and a low compression led to products with a potential high approval by consumers.

Bioactive Compounds, Antioxidant Activity, and Sensory Analysis of Rice-Based Extruded Snacks-Like Fortified with Bean and Carob Fruit Flours

Generally, extruded gluten-free foods are mostly phytochemically deficient. In this study inositol phosphates, α-galactosides, lectins, protease inhibitors, and phenols, their antioxidant activity and sensorial analysis of some rice/bean/whole carob fruit flour blends were determined in unprocessed (controls) and extruded formulations. The fortification of rice-based extrudates with both legumes has a positive influence on both their bioactive compound content and their acceptability by consumers. The extruded formulations contained around twice as much (p < 0.05) total α-galactosides than their unprocessed counterparts. Extrusion significantly reduced the phytic acid content (10%) and significantly increased the less phosphorylated forms (16%-70%). After extrusion, the lectins and protease inhibitors were eliminated. The different phenolic compounds mostly increased (11%-36%), notably in the formulations with carob fruit. The antioxidant activity and the different groups of phenols showed a positive correlation in the extrudates. All the experimental extrudates had higher amounts of bioactive compounds than the commercial extruded rice. Considering the amount of phytochemicals determined in the novel gluten-free extrudates and the scores of sensorial analysis, formulations containing 20%-40% bean and 5% carob fruit could be adequate in promoting health-related functions, helping to increase pulse consumption, and allowing the food industry to satisfy consumers' requirement for functional foods.

Effect of extrusion on physicochemical properties, functional properties and antioxidant activities of shrimp shell wastes protein

Different conditions of extrusion variables (temperature and moisture content) were applied to shrimp shell wastes (SSW), and its effects on the physicochemical, functional properties and antioxidant activities of shrimp shell wastes protein (SSWP) were investigated. The results showed that extrusion caused marked improvements in the protein content and yields compared with the control, and it resulted in the changes of SSWP on the amino acids composition, functional properties, thermal properties and morphological properties. The protein from extruded SSW showed better antioxidant activities than the untreated one. When the six samples were compared by principal component analysis, the protein obtained at the conditions of 25% moisture content at 150 °C (T3M2) were observed to have the highest comprehensive principal component values. The results provided a better choice for SSW in extrusion processing, which would be helpful for the SSWP related products in the food industry.