Influence of processing conditions on apparent viscosity and system parameters during extrusion of distiller's dried grains-based snacks

Investigating extrusion impact on functional, textural properties, morphological structure, and molecular interactions in hulless barley-based extruded snacks supplemented with mung bean

The effect of varying extrusion conditions on the functional properties of hulless barley-mung bean (70:30) extruded snacks was investigated using response surface methodology with feed moisture (FM), barrel temperature (BT), and screw speed (SS) as process variables. Results revealed significant impacts on functional characteristics with varying extrusion conditions. Bulk density (BD) of extruded snacks ranged from 0.24 to 0.42 g/cm3, showing that lower FM and higher BT results in lower BD while it increased with increasing FM, SS, and BT. The expansion ratio (ER) of extruded snacks ranged between 2.03 and 2.33, showing BT and SS had a desirable positive effect, whereas increasing FM led to decreased ER. Increasing BT and SS depicted a negative effect on water absorption index, whereas FM showed positive effect, which ranged between 4.21 and 4.82 g/g. A positive effect on water solubility index was depicted by BT and SS, which ranges between 9.01% and 13.45%, as higher SS and BT led to starch degradation and increased solubility suggesting better digestibility. The hardness of extruded snacks ranged from 32.56 to 66.88 Newton (N), showing increasing FM increased hardness, whereas higher SS and BT resulted in lowering the hardness. Scanning electronic microscope (SEM) analysis revealed structural changes in extrudates in comparison with nonextruded flour, indicating starch gelatinization and pore formation affected by varying processing parameters. Shifts in absorption bands were observed in Fourier transform infrared spectroscopy (FT-IR), suggesting structural changes in starch and protein. Understanding the effects of extrusion parameters on product properties can help tailored production to meet consumers' preferences and the development of functional snacks with improved nutritional quality.

Extrusion parameters and physical transformations of an extrudate for fish: Effect of the addition of hydrolyzed protein flour from by-products of Oncorhynchus mykiss

Introduction

The food industries play a fundamental role in feeding for the functions of animal metabolism. Fish feed extrusion cooking includes process-independent factors such as temperature (°C), screw speed (RPM), throughput, feed, and moisture content that influence the final product's nutritional value and physical properties. The evidence suggests that the application of hydrolyzed protein flour (HPH) is a crucial step for the techno-functional properties of the product. Therefore, this work aimed to study the effect of hydrolyzed protein meal from silage of trout (Oncorhynchus mykiss) on the parameters of the extrusion system and their physical transformations.

Methods

In this study, the influence of hydrolyzed protein meals ranges between 10 and 30% as a substitute for fish meals. The physical properties of the extrudate were monitored, evaluating the hardness, durability, buoyancy, expansion index, and apparent density.

Results

Consistent with this, parameters such as feed composition, screw speed, moisture content, and extrusion process affected the composition and properties of the final product.

Discussion

The physical properties indicated that the hydrolyzed protein flour presented cohesiveness and decreased the mean retention time in the extruder barrel and the specific mechanical energy (SME). Hydrolyzed protein flour during the extrusion process produces pellets with high durability and low hardness due to the high porosity presented, which allows for obtaining nutritional characteristics in the extruded product.

Food extrusion: An advanced process for innovation and novel product development

Extrusion is a versatile process capable of producing a variety of new and novel foods and ingredients, thus increasing manufacturing opportunities. Further, it could provide nutritious, safe, sustainable, and affordable foods, especially directed at individualized consumer needs. In addition to past research efforts, more investigations should be conducted in order to refine, redesign, or develop new extrusion processing technologies. The present review highlights the current advances made in new and novel food product development by considering the extrusion process, the influencing parameters, and product characteristics and properties; the most promising extrusion processes that can be used in novel food product and ingredient development, such as extrusion cooking, hot-melt extrusion, reactive extrusion, and extrusion-based 3D printing; the possibilities of using various raw materials in relation to process and product development; and the needs for product development modeling along with extrusion process design and modeling. In correlation with extruded product development, topics that merit further investigation may include structure formation, plant and animal biopolymers functionalization, biopolymer reactions, process simulation, modeling and control, engineering and mechanical aspects of extruders, analysis of pre-processing treatments, as well as prototyping, risk analysis, safety, sensory and consumer acceptance.

Optimizing the extrusion conditions for the production of expanded intermediate wheatgrass (Thinopyrum intermedium) products

Abstract

In this study, the effects of extrusion conditions such as feed moisture content (20%, 24%, and 28%), screw speed (200, 300, and 400 rpm), and extrusion temperature (130, 150, and 170°C) on the physical and functional properties (moisture content, expansion ratio, bulk density, hardness, water absorption index [WAI], water solubility index [WSI]) of intermediate wheatgrass (IWG) were investigated for the first time. Response surface methodology was used to model and optimize the extrusion conditions to produce expanded IWG. The model coefficient of determination (R²) was high for all the responses (0.87–0.98). All the models were found to be significant (p < 0.05) and were validated with independent experiments. Generally, all the extrusion conditions were found to have significant effects on the IWG properties measured. Increasing the screw speed and decreasing the extrusion temperature resulted in IWG extrudates with a high expansion ratio. This also resulted in IWG extrudates with generally low hardness and bulk density. Screw speed was found to have the most significant effect on the WAI and WSI, with increasing screw speed resulting in a significant (p < 0.05) decrease in WAI and a significant (p < 0.05) increase in WSI. The optimum conditions for obtaining an IWG extrudate with a high expansion ratio and WAI were found to be 20% feed moisture, 200 –356 rpm screw speed, and 130–154°C extrusion temperature.

Practical Application

Extrusion cooking was employed in the production of expanded IWG. This research could provide a foundation to produce expanded IWG, which can potentially be used as breakfast cereals and snacks. This is critical in the efforts to commercialize IWG for mainstream food applications.

Effect of Extrusion Temperature and Feed Moisture Content on the Microstructural Properties of Rice-Flour Pellets and Their Impact on the Expanded Product

Extrusion can lead to an expanded product or to a slightly expanded pellet, known as a third-generation (3G) snack. In this case, expansion occurs subsequently, in an independent thermal device (e.g., oven), out of the extruded pellet. During both processes, several structural changes occur which are linked to processing conditions, including cooking temperature, screw speed, formulation, and initial moisture content. However, a clear relationship between processing variables and the structure of pellets and expanded products has not yet been identified. Accordingly, this work aimed to study the effect of extrusion temperature (110, 135, and 150 °C) and moisture content (27, 29, and 31%) in rice-flour pellets and their microwave expansion, through a microstructural approach using micro-CT. The results showed that the lowest moisture content (27%) and the highest extrusion temperature (150 °C) led to the highest pellet volume and the highest wall thickness, which in turn led to the highest expansion after microwave heating (50 s, 800 W). Interestingly, no significant differences were observed when analyzing the ratio between the volume of the expanded products and the volume of the pellet (~2.4) when using the different processing conditions.

Utilization of Food Processing By-products in Extrusion Processing: A Review

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.

Effects of corn distillers dried grains on dough properties and quality of Chinese steamed bread

Chinese steamed bread (CSB) accounts for 30% of the wheat end-use in China. CSB was studied as a platform for fiber and protein enrichment, employing corn distillers dried grains. Food grade distiller's grain (FDDG) processed from co-products from the corn ethanol industry was used as the enrichment ingredient. Since CSB uses a lean formula with little or no added sugar or fat, it relies entirely on fermentation and steaming for flavor and texture development. FDDG was used to replace 0%-25% all-purpose flour (APF) in CSB formulations. Effects of FDDG on dough properties and quality of CSB were evaluated by instrumental (Farinograph, Mixolab, and Texture Analyzer), nutritional, and sensory methods. Protein and dietary fiber contents showed significant increases to 18.8% and 15.3%, respectively, for 100 g of steamed bread (25% FDDG db). Fiber in 100 g of fresh FDDG CSB ranged from 2.8 to 7.7 g. FDDG fortified doughs demonstrated higher water absorption, while dough development time, dough stability, and dough extensibility decreased significantly with partial APF replacement. FDDG contributed to increased hardness and adhesiveness in the CSB. Crumb analysis revealed reduced number of gas cells at higher FDDG substitution. FDDG enrichment reduced brightness (L*) of flour blends and CSB. Rheological and sensory analysis showed an upper level of FDDG substitution of 15% was acceptable without detriment to dough functionality, texture, and taste.

Corn dried distillers grains with solubles (cDDGS) in the diet of pigs change the expression of adipose genes that are potential therapeutic targets in metabolic and cardiovascular diseases

Background

Corn dried distillers grains with solubles (cDDGS) are a byproduct of biofuel and alcohol production. cDDGS have been used in pig feed for many years, because they are readily available and rich in protein, fiber, unsaturated fatty acids and phytosterols. However, feed mixtures too high in cDDGS result in the worsening of backfat quality. We performed RNA-sequencing analysis of backfat from crossbred pigs fed different diets. The diets were isoenergetic but contained different amounts of cDDGS and various sources of fats. The animals were divided into four dietary groups during the two months of experimentation: group I (control (-cDDGS+rapeseed oil)), group II (+cDDGS+rapeseed oil), group III (+cDDGS+beef tallow), and group IV (+cDDGS+coconut oil). The aim of the present experiment was to evaluate changes in the backfat transcriptome of pigs fed isoenergetic diets that differed in cDDGS presence.

Results

Via DESeq2 software, we identified 93 differentially expressed genes (DEGs) between groups I and II, 13 between groups I and III, and 125 between groups I and IV. DEGs identified between group I (-cDDGS+rapeseed oil) and group II (+cDDGS+rapeseed oil) were highly overrepresented in several KEGG pathways: metabolic pathways (FDR < 1.21e-06), oxidative phosphorylation (FDR < 0.00189), fatty acid biosynthesis (FDR < 0.00577), Huntington’s disease (FDR < 0.00577), fatty acid metabolism (FDR < 0.0112), Parkinson’s disease (FDR < 0.0151), non-alcoholic fatty liver disease (NAFLD) (FDR < 0.016), Alzheimer’s disease (FDR < 0.0211) and complement and coagulation cascades (FDR < 0.02).

Conclusions

We observed that the addition of cDDGS positively affects the expression of several genes that have been recently proposed as potential targets for the treatment of obesity, diabetes, cardiovascular disease, and Alzheimer’s disease (e.g., FASN, AACS, ALAS1, HMGCS1, and VSIG4). Thus, our results support the idea of including cDDGS into the diets of companion animals and humans and encourage research into the bioactive ingredients of cDDGS.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5265-x) contains supplementary material, which is available to authorized users.

Physicochemical and nutritional properties of extrudates from food grade distiller's dried grains, garbanzo flour, and corn grits

Distiller's dried grains and garbanzo flour were blended with corn grits for the development of extruded snacks using a single screw extruder. Distiller's dried grains were processed for food application and termed as food grade distiller's dried grains or FDDG. Effects of different level of FDDG addition (0%-20%) and extrusion process parameters such as barrel and die temperature (100-140°C), screw speed (100-200 rpm), and feed moisture content (14%-20% wet basis) on the physical properties (expansion ratio, bulk density, color parameters), functional properties (water absorption and solubility indices), and nutritional properties (total dietary fiber, soluble and insoluble dietary fiber and protein content) of the extrudates were investigated and optimized using response surface methodology. FDDG incorporation had a significant effect (p < 0.05) on the total dietary fiber, color parameters, water solubility, and water absorption indices of the extruded snacks. Desirable expanded extrudates with a high level of total dietary fiber and protein were obtained with blends containing 20% FDDG extruded at 140°C extrusion temperature, 167 rpm screw speed, and 19% feed moisture content. Results indicate garbanzo flour, and FDDG can be successfully blended with corn grits to produce nutritious gluten-free extruded snacks which are high in protein and dietary fiber.

Single screw extrusion of apple pomace-enriched blends: Extrudate characteristics and determination of optimum processing conditions

Response surface methodology was used to investigate the single screw extrusion of apple pomace–defatted soy flour–corn grits blends and the product properties. Five different blends at a level of 0–20% w/w apple pomace were extrusion cooked with varied barrel and die temperature (100–140℃), screw speed (100–200 rpm), and feed moisture content (14–20% wet basis). Increasing apple pomace content in the blends significantly ( P < 0.05) increased the bulk density, the total phenolic content, and the antioxidant activity of the extrudates. The expansion ratio increased with pomace inclusion level of 5% but decreased significantly ( P < 0.05) at higher levels of pomace inclusion (10–20%). Moisture content had quadratic influence on water absorption and solubility indices. Optimal extrusion cooking conditions most likely to produce apple pomace-enriched extruded snack products were at 140℃ barrel and die temperature, 20% feed moisture content, and 200 rpm screw speed. The results indicated active interaction between apple pomace and starch during expansion process.

Influence of processing conditions on apparent viscosity and system parameters during extrusion of distiller's dried grains-based snacks

A combination of different levels of distillers dried grains processed for food application (FDDG), garbanzo flour and corn grits were chosen as a source of high-protein and high-fiber extruded snacks. A four-factor central composite rotatable design was adopted to study the effect of FDDG level, moisture content of blends, extrusion temperature, and screw speed on the apparent viscosity, mass flow rate or MFR, torque, and specific mechanical energy or SME during the extrusion process. With increase in the extrusion temperature from 100 to 140°C, apparent viscosity, specific mechanical energy, and torque value decreased. Increase in FDDG level resulted in increase in apparent viscosity, SME and torque. FDDG had no significant effect (p > .5) on mass flow rate. SME also increased with increase in the screw speed which could be due to the higher shear rates at higher screw speeds. Screw speed and moisture content had significant negative effect (p < .05) on the torque. The apparent viscosity of dough inside the extruder and the system parameters were affected by the processing conditions. This study will be useful for control of extrusion process of blends containing these ingredients for the development of high-protein high-fiber extruded snacks.