Residence Time Distribution of Soy Protein Isolate and Corn Flour Feed Mix in a Twin-Screw Extruder

Microbial community structure of plant-based meat alternatives

A reduction in animal-based diets has driven market demand for alternative meat products, currently raising a new generation of plant-based meat alternatives (PBMAs). It remains unclear whether these substitutes are a short-lived trend or become established in the long term. Over the last few years, the trend of increasing sales and diversifying product range has continued, but publication activities in this field are currently limited mainly to market research and food technology topics. As their popularity increases, questions emerge about the safety and nutritional risks of these novel products. Even though all the examined products must be heated before consumption, consumers lack experience with this type of product and thus further research into product safety, is desirable. To consider these issues, we examined 32 PBMAs from Austrian supermarkets. Based on 16S rRNA gene amplicon sequencing, the majority of the products were dominated by lactic acid bacteria (either Leuconostoc or Latilactobacillus), and generally had low alpha diversity. Pseudomonadota (like Pseudomonas and Shewanella) dominated the other part of the products. In addition to LABs, a high diversity of different Bacillus, but also some Enterobacteriaceae and potentially pathogenic species were isolated with the culturing approach. We assume that especially the dominance of heterofermentative LABs has high relevance for the product stability and quality with the potential to increase shelf life of the products. The number of isolated Enterobacteriaceae and potential pathogens were low, but they still demonstrated that these products are suitable for their presence.

Effects of Process Parameters on the Fibrous Structure and Textural Properties of Calcium Caseinate Extrudates

Textured calcium caseinate extrudates are considered promising candidates in producing fish substitutes. This study aimed to evaluate how the moisture content, extrusion temperature, screw speed, and cooling die unit temperature of the high-moisture extrusion process affect the structural and textural properties of calcium caseinate extrudates. With an increase in moisture content from 60% to 70%, there was a decrease in the cutting strength, hardness, and chewiness of the extrudate. Meanwhile, the fibrous degree increased considerably from 1.02 to 1.64. The hardness, springiness, and chewiness showed a downward trend with the rise in extrusion temperature from 50 °C to 90 °C, which contributed to the reduction in air bubbles in the extrudate. Screw speed showed a minor effect on fibrous structure and textural properties. A low temperature (30 °C) in all cooling die units led to damaged structure without mechanical anisotropy, which resulted from fast solidification. These results show that the fibrous structure and textural properties of calcium caseinate extrudates can be effectively manipulated by adjusting the moisture content, extrusion temperature, and cooling die unit temperature.

Conformational changes and physicochemical attributes of texturized pea protein isolate-konjac gum: With a new perspective of residence time during extrusion

The present study aimed to investigate the effects of different extrusion temperatures (110, 130 and 150 °C) and konjac gum addition (0.1 %, 0.2 %, and 0.3 %) on the flow behavior, physicochemical properties and microstructure of extruded pea protein isolate (PPI). The results showed that the textured protein could be improved by enhancing the extrusion temperature and adding konjac gum during extrusion. The water/oil holding capacity of PPI decreased and the SH content increased after extrusion. With temperature and konjac gum content increased, the β-sheet of extruded proteins transformed to other secondary structural components, and Trp residue transformed to a more polar environment, illustrating the changes in protein conformation. All extruded samples presented as yellow hue with little green and higher lightness, while excessive extrusion process reduced the brightness and promoted more formation of browning pigments. Extruded protein showed more associated layered with some air pores, and its hardness and chewiness increased with the increase of temperature and konjac gum concentration. Cluster analysis showed that the addition of konjac gum could effectively improve the quality characteristics of pea protein under low temperature extrusion, and the effect was similar to that of high temperature extrusion product. With the increase of konjac gum concentration, the flow pattern of protein extrusion gradually converted from plug flow to mixing flow, and the disorder degree of polysaccharide protein mixing system was enhanced. Moreover, Yeh-jaw model showed better fitting effect in F(θ) curves compared to Wolf-white.

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.

Validation of process technologies for enhancing the safety of low-moisture foods: A review

The outbreaks linked to foodborne illnesses in low-moisture foods are frequently reported due to the occurrence of pathogenic microorganisms such as Salmonella Spp. Bacillus cereus, Clostridium spp., Cronobacter sakazakii, Escherichia coli, and Staphylococcus aureus. The ability of the pathogens to withstand the dry conditions and to develop resistance to heat is regarded as the major concern for the food industry dealing with low-moisture foods. In this regard, the present review is aimed to discuss the importance and the use of novel thermal and nonthermal technologies such as radiofrequency, steam pasteurization, plasma, and gaseous technologies for decontamination of foodborne pathogens in low-moisture foods and their microbial inactivation mechanisms. The review also summarizes the various sources of contamination and the factors influencing the survival and thermal resistance of pathogenic microorganisms in low-moisture foods. The literature survey indicated that the nonthermal techniques such as CO₂ , high-pressure processing, and so on, may not offer effective microbial inactivation in low-moisture foods due to their insufficient moisture content. On the other hand, gases can penetrate deep inside the commodities and pores due to their higher diffusion properties and are regarded to have an advantage over thermal and other nonthermal processes. Further research is required to evaluate newer intervention strategies and combination treatments to enhance the microbial inactivation in low-moisture foods without significantly altering their organoleptic and nutritional quality.

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.