High-Moisture Extrusion: Meat Analogues

R. Osen , U. Schweiggert-Weisz , in Reference Module in Food Science, 2016

Control of Fiber Formation

One major characteristic of high-moisture meat substitutes is their unique fibrous structure which gives the products a meatlike appearance. By variation of the process conditions, it is possible to generate products with the appearance of whole muscle meat that resembles, e.g., chicken or beef. The fiber length, thickness, or fiber orientation can be controlled and requires the unique combination of extrusion operation conditions. Based on the system analytics model introduced by Meuser and Van Lengerich (1984) that describes the 'black-box' extrusion process, Figure 5 illustrates the input process variables and the resulting parameters inside the extruder and the cooling die, all which contribute to the final fiber formation of plant proteins.

Figure 5. Input variables and dependent parameters during high-moisture extrusion cooking.

 Adapted from Camire, M.E., 1998. Chemical changes during extrusion cooking – recent advances. In: Process-Induced Chemical Changes in Food, vol. 434, pp. 109–121 with permission.

The control of fiber formation requires specific physicochemical reactions of the protein mass which depend on the system parameters inside the extruder and the cooling die that in turn are the result of the variety of process variables.

Based on the fundamental work of Noguchi (1990) and Cheftel et al. (1992), several studies were published on the effect of extrusion process parameters on the structural and sensory properties of high-moisture extrudates using soy protein. Moisture content is an important factor on the overall product texture. Lower moisture content resulted in higher die pressure, harder texture, and lower total protein solubility and the products were tougher, chewier, and more cohesive (Lin et al., 2000, 2002). Furthermore, the cooking temperature highly affects the texture properties (Noguchi, 1990; Thiebaud et al., 1996; Chen et al., 2010b; Osen et al., 2014). Figure 6 shows the influence of cooking temperature on the texture properties of pea protein isolates extruded at 55% moisture.

Figure 6. Cutting strength of high-moisture extrudates made of pea protein isolate as a function of cooking temperature at 55% moisture content (w/w).

 Samples were evaluated vertical (longitudinal strength, FL) and parallel (transverse strength, FT) to the direction of extrudate outflow from the extruder. Reprinted with permission from Elsevier; Osen, R., Toelstede, S., Wild, F., Eisner, P., Schweiggert-Weisz, U., 2014. High moisture extrusion cooking of pea protein isolates: raw material characteristics, extruder responses, and texture properties. J. Food Eng. 127, 67–74.

At temperatures below 120   °C, the samples exhibited a doughlike soft texture without any fibrous structures and both longitudinal and transversal strength were low. Increasing barrel temperature resulted in increased cutting strength in the longitudinal direction while transverse strength remained constant as a result of the laminar flow profile in the cooling die. The extrudates started to display multilayered structures with layers parallel to the die wall and fine fibers appearing upon tearing, especially at 140   °C. At temperatures as high as 160   °C, the samples became less fibrous with a smooth surface. Only upon tearing, predominant lengthwise oriented fibers appeared. The minimal texturization temperature was between 100   °C and 120   °C, with an optimum around 140   °C, while the high temperature (160   °C) produced samples that were already too rigid and dense. Besides cooking temperature, the increased shear through the use of aggressive screw configurations can produce extrudates with a high tensile strength (Fang et al., 2013).

In order to describe the microstructure and textural characteristics of fibrous protein products made by high-moisture extrusion, several methods have been applied. The most common ones are based on microscopy (Lin et al., 2002; Noguchi, 1990; Ranasinghesagara et al., 2005) and texture profile analysis (Chen et al., 2010b; Fang et al., 2014; Lin et al., 2000). The determination of the cutting strength in longitudinal and transverse directions, with respect to the flow direction in the cooling die, has been used as a simple method to quantify the fiber formation (Chen et al., 2010b; Fang et al., 2014; Osen et al., 2014). Other methods focusing on quantifying fiber formation use fluorescence polarization spectroscopy (Yao et al., 2004) or a real-time scanning system based on photon migration (Ranasinghesagara et al., 2006). However, up to now these analytical methods cannot replace sensory evaluation because they do not provide enough data to fully cover the combination of all texture attributes.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780081005965030997

Soy-Based Fermented Foods

D.K. O'Toole , in Reference Module in Food Science, 2016

Tempeh

'Tempeh' is a fermented soybean product and meat substitute that originated in Indonesia. It is probably the first 'fast food' in that it can be deep-fried in 3–4  min or cooked in 10   min. The production of tempeh is outlined in Figure 1 . In the first step, the soybeans are soaked in water or acidified water at room temperature. During this stage, a partial germination of the soybeans may occur depending on the amount of O2 available to the seed, and acid is produced by bacteria growing in the soak water. Depending on the temperature during soaking, bacteria reach 108–1010 colony-forming units per ml after 24–36   h. The pH drops from ∼   6.5 to ∼   4.5 due to the growth of the acid-producing bacterial species – for example, Lactobacillus casei, Streptococcus faecium, Staphylococcus epidermidis, and Klebsiella pneumoniae – that are present naturally on the soybeans. The acid helps to prevent the growth of undesirable microorganisms, but any partial seed germination can affect the protein properties of the soybean and the subsequent fungal growth phase. The bacteria that grow in the steeping water produce vitamin B12, a significant nutrient in tempeh. The most desirable bacterial species for this stage is K. pneumoniae, but other pure bacterial starter cultures can perform the same function.

Figure 1. A flow diagram of the production of tempeh, an Indonesian fermented soybean product. The fungal mycelia knit the soybeans into a cake.

The soaked beans are dehulled and carefully cooked to avoid overcooking or undercooking of the beans. The soybeans are then drained, cooled below 35   °C, and dusted with wheat flour to provide a good source of fermentable carbohydrate, and inoculated. The desirable fungal species for successful tempeh production, whether arising from environmental inoculation or from pure starter inoculation, are Rhizopus oligosporus (e.g., NRRL 2710), R. stolonifer, R. arrhizus, R. oryzae, R. formosaensis, and R. achlamydosporus. The spores of R. oligosporus are produced commercially in Indonesia for industrial-scale tempeh production. During the fungal growth phase, the O2 level must be controlled at a reduced level; otherwise, the fungus will grow too quickly and form black spore masses that degrade the quality of the tempeh. The traditional way to control O2 is to wrap the inoculated beans in banana leaves, but a modern innovation is the use of microperforated polyethylene plastic. The fungus grows and mycelia knit the beans into a firm cake to give the characteristic meaty texture.

The enzymes from the fungi transform the soybeans making them more nutritious by hydrolyzing the protein and complex carbohydrates and increasing the levels of the vitamins – riboflavin, niacin, pantothenic acid, and vitamin B6. Tempeh must be consumed fairly quickly. Defects include (1) black patches due to fungal sporulation, (2) slime due to excessive bacterial growth because of too little O2 or a temperature of 42   °C, and (3) a yellow color due to growth of toxic fungi. The yellow color indicates that the tempeh is highly toxic and it should not be eaten.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780081005965001293

SOYBEAN | Soy-Based Fermented Foods

D.K. O'Toole , in Encyclopedia of Grain Science, 2004

Tempeh

"Tempeh" is a fermented soybean product and meat substitute that originated in Indonesia. It is probably the first "fast food" in that it can be deep-fried in 3–4  min or cooked in 10   min. The production of tempeh is outlined in Figure 1 (see SOYBEAN | Soymilk, Tofu, and Okara). In the first step the soybeans are soaked in water or acidified water at room temperature. During this stage a partial germination of the soybeans may occur depending on the amount of O2 available to the seed, and acid is produced by bacteria growing in the soak water. Depending on the temperature during soaking, bacteria reach 108–1010 colony-forming units per ml after 24–36   h. The pH drops from ∼6.5 to ∼4.5 due to the growth of the acid-producing bacterial species – e.g., Lactobacillus casei, Streptococcus faecium, Staphylococcus epidermidis, and Klebsiella pneumoniae – that are present naturally on the soybeans. The acid helps to prevent the growth of undesirable microorganisms, but any partial seed germination can affect the protein properties of the soybean and the subsequent fungal growth phase. The bacteria that grow in the steeping water produce vitamin B12, a significant nutrient in tempeh. The most desirable bacterial species for this stage is K. pneumoniae, but other pure bacterial starter cultures can perform the same function.

Figure 1. A flow diagram of the production of tempeh, an Indonesian fermented soybean product. The fungal mycelia knit the soybeans into a cake.

The soaked beans are de-hulled and carefully cooked to avoid overcooking or undercooking of the beans. The soybeans are then drained, cooled below 35   °C, and dusted with wheat flour to provide a good source of fermentable carbohydrate, and inoculated. The desirable fungal species for successful tempeh production, whether arising from environmental inoculation or from pure starter inoculation, are Rhizopus oligosporus (e.g., NRRL-2710), R. stolonifer, R. arrhizus, R. oryzae, R. formosaensis, and R. achlamydosporus. The spores of R. oligosporus are produced commercially in Indonesia for industrial-scale tempeh production. During the fungal growth phase the O2 level must be controlled at a reduced level, otherwise the fungus will grow too quickly and form black spore masses that degrade the quality of the tempeh. The traditional way to control O2 is to wrap the inoculated beans in banana leaves, but a modern innovation is the use of microperforated polyethylene plastic. The fungus grows and mycelia knit the beans into a firm cake to give the characteristic meaty texture.

The enzymes from the fungi transform the soybeans making them more nutritious by hydrolyzing the protein and complex carbohydrates and increasing the levels of the vitamins – riboflavin, niacin, pantothenic acid, and vitamin B6. Tempeh must be consumed fairly quickly. Defects include: (1) black patches due to fungal sporulation, (2) slime due to excessive bacterial growth because of too little O2 or a temperature of 42   °C, and (3) a yellow color due to growth of toxic fungi. The yellow color indicates that the tempeh is highly toxic and it should not be eaten.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B0127654909001531

3D Printing of Food

Jie Sun , ... Dejian Huang , in Reference Module in Food Science, 2018

Bioprinting of Synthetic Meat

Intensive animal farming is perceived as a key factor for global warming. Bioprinting synthetic meat or meat substitute is proposed as an alternative way for meat production. Bioprinting is the use of 3D printing technology to fabricate tissue scaffold structures with bioink, which consists of mediums, stem cells and so on. The printed scaffold structures are placed in an incubator so that the stem cells can rapidly replicate to form muscle fibers and become meat. The ideal scaffold is edible so the meat does not have to be removed, and periodically moves to stretch the developing muscle, thereby simulating the animal body during normal development.

Companies such as Modern Meadow, Meat and Livestock Australia, have investigated this printing technology. The printed meat-based products have looks, smells, and tastes similar to actual meat, but a softer texture. This may be a low cost and easily digestible option for the elderly who struggle with chewing and swallowing difficulties. US Researchers even filed a patent to enhance the culture process, and claimed that was scalable meat production in vitro for dietary nutrition (Genovese et al., 2016). For vegetarians, printed meat somewhat circumvents concerns about harmful or destructive use of animals for food. Australia government has sponsored an ethical research program for uncovering and articulating community concerns about this emerging technology.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780081005965218933

Facilitators and Barriers for Foods Containing Meat Coproducts

Maeve Henchion , Mary McCarthy , in Sustainable Meat Production and Processing, 2019

12.5 Lessons From Other Novel Food Sources

An examination of the consumer related barriers and facilitators to acceptance of other "culturally inappropriate" novel meat substitutes may offer some interesting insights (due to the similarity in many of these substitutes characterizes, from a consumer perspective, to those of foods containing meat coproducts). The novel components of these foods generally fall outside what is culturally acceptable as food (at best they are culturally inappropriate), they are unfamiliar to the person and there is a level of perceived uncertainty/risk in their consumption from performance, psychological, and social perspectives. A lot of research attention has been focused on the potential for using insects as a food solution in recent years, particularly given global demands on animal protein. This effort provides an opportunity for learning in relation to food products containing meat coproducts. This is because while insects have been consumed for thousands of years, and are part of the traditional diets of at least 2  billion people (Van Huis et al., 2013), they will need to be consumed in parts of the world in which they have not traditionally been consumed if they are to present a solution to the global "protein dilemma."

For example, it is argued that they offer environmental benefits, requiring less land and water and emitting lower levels of greenhouse gases and ammonia than regular livestock. Indeed, the suggestion is that of the range of potential meat substitutes, insect flour–based alternatives have among the lowest environmental impact (Smetana et al., 2016). Furthermore, they can be reared on organic side streams thus reducing waste streams and adding value. They are also argued to perform better in terms of feed conversion efficiency than other animals due to their cold-blooded nature. However, as with any food source, there are several concerns associated with their consumption. Firstly, the environmental impact of insects is influenced by the insect species in question and their associated diet (this also determines whether they can be used for food or feed purposes from a regulatory perspective) (Smetana et al., 2016). While they have a favorable nutritional profile, many insects are deficient in certain essential amino acids (Belluco et al., 2013). Furthermore, question marks remain with regards to their safety due to a lack of research in this area. Finally, in Western cultures, there is a reluctance to consume insects. They are frequently regarded as pests and a source of contamination, and thus to be avoided. Hence, while many of the arguments in favor of and against consuming insects echo arguments in favor of and against increased consumption of meat coproducts, from a consumer perspective one of the key commonalities is the challenge associated with ideation or the "yuck" factor.

Consequently, it is unsurprising that consumer willingness to consume is generally low. To illustrate, Verbeke (2015) work suggests that more than four in five of Belgians are unwilling to eat insects as a meat substitute. One may argue that this is as would be expected, given that a disgust response may be triggered as part of a protective mechanism against ingesting potentially harmful substances (Hartmann and Siegrist, 2017). Taking the disgust response (which is somewhat typical in western societies when considering insect as a food source) into account the fact that one in five of people were willing to consume these foods warrants mention. This suggests that the more venturesome, novelty-seeking innovators are willing to take a "leap of faith" while also possibly recognizing that insects form parts of the food menu in other societies. While the aforementioned characteristics of these products suggest a slow consumer adoption rate, a focus on innovators in the early phase of product introduction is important to illustrate the products in use and thus legitimize it within the broader market (Goldsmith and Flynn, 1992). Indeed, the actions and reactions of this cohort strongly determine the direction and pace of adoption of any novel meat substitutes.

Moving potential consumers through the first three stages of the adoption process (awareness, interest, and evaluation) may be facilitated by the "novelty factor," however major challenges lie in stages 4 (product trial) and 5 (product adoption). This draws our attention to factors that facilitate positive evaluations and product trials of these novel foods. Research suggests that the order of product launches is important. Transitioning consumers from rejecting these culturally inappropriate foods to integrating them in their everyday food lives requires positioning them within what is familiar (e.g., burgers, chips, sauce dishes), removing evidence of their origins (e.g., present in the form of flour, patty, or mince), and ensuring that they look and smell appealing (Schosler et al., 2012; Megido et al., 2016; Hartmann and Siegrist, 2017). Megido et al. (2016, p. 237) suggest, in the case of insect-based alternative meat products, the most likely to succeed are those with "minced or powdered insects incorporated into ready-to-eat preparations." Tan et al. (2016) warn that trial may not imply acceptance, it may just represent curiosity. Consequently, while attention should be given to enticing individual to try, there is a need to draw on conventional wisdom on the necessary elements for market success of any new food product. Taste, value for money, convenience, availability, and relevance within everyday food practices are central to moving consumers from trial to repeat purchases (House, 2016). Attention needs to be given to targeting market segments to ensure that the product offerings are congruent with expectations and products are designed to target those open to trying and using such products (coproduct or nonmeat-based substitutes). Within this context factors such as cultural background, gender, age, and experience have been noted as important (Verbeke, 2015; Tan et al., 2016). In line with this thinking Apostolidis and McLeay (2016) argue that to reduce meat consumption through substitution activities and interventions should be "holistic and target specific consumer segments."

Greehy et al. (2013)work on citizens' evaluation of novel food technologies draws attention to perceived product relevance and the importance of unique tangible benefits. They suggest if either of these are absent one can anticipate that the product/technology will be rejected. When considering meat substitutes it is interesting to note that environmental benefits are central to their communication narrative, however Hartman and Siegrist (2017) highlight that consumer awareness of the suggested environmental impact of meat production (based on life-cycle analysis) is low. Additionally, the strong connection and ties to consuming meat held by many may lead them to questions about the overall relevance of these substitutes in their food lives. As a result, overall motivation to change meat consumption patterns is low (Hartmann and Siegrist, 2017).

Irrespective of the food solution a significant challenge lies in achieving market success where the food falls into the category of being culturally inappropriate.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780128148747000122

New Sources of Animal Proteins: Cultured Meat

M.J. Post , J.-F. Hocquette , in New Aspects of Meat Quality, 2017

3.2 Mimicry

The premise for cultured meat is that the consumer continues to expect meat as a readily available and affordable food choice and not a meat substitute with perceived lower quality. To what extent can cultured meat mimic livestock produced meat? Although this question directs primarily to sensory factors of meat, such as color, flavor, and tenderness, it is likely that the biochemical and structural composition of the engineered tissue needs to be similar to the natural product.

The color of currently formed muscle fibers is yellow, not pink or red. Culturing the cells at ambient oxygen conditions apparently suppresses myoglobin expression, responsible for most of meat's red color (USDA, 1998). Many studies have shown that myoglobin expression can be increased by culturing bovine muscle fibers under low oxygen conditions (Kanatous and Mammen, 2010). The results of Maastricht University in bovine myoblasts confirm those observations (unpublished results). Further metabolic studies on heme and iron incorporation have not been performed yet. Heme and iron are likely to contribute to the taste of meat as well.

The flavor of meat is the result of a highly complex composition of proteins, sugars, and aromates (Mottram, 1998). As the myoblasts are essentially the same cells as the ones producing livestock beef, we assume that the biochemical composition of the tissue can be made similar. If that is the case, the taste should be replicated as well. The proof-of-concept hamburger was made solely of muscle cells and an occasional fibroblast. Aromates residing in the fat fraction of meat were therefore largely lacking. To complement flavor, but also to add nutritional value and enhance the texture of meat, adipose tissue needs to be added to the product. Adipose tissue can be cultured from mesenchymal stem cells, adipose tissue–derived stem cells or perhaps even from myoblasts (Vettor et al., 2009). The most common cell source is the mesenchymal stem cell fraction, typically derived from a bone marrow aspirate. The ability to differentiate along the adipogenic line is one of the defining criterions for mesenchymal stem cells. A cocktail of dexamethasone, iso-butyl-methyl-xanthine (IBMX) and insulin is used to drive the differentiation. This cocktail is not compatible with food production. Adipogenic differentiation involves the activation of several transcription factors including PPAR-γ and C/EBP-β. The dexa/IBMX/insulin mix activates these pathways at several levels. As free fatty acids (FFAs) are the natural ligands for PPAR-γ, several FFAs have been tested for their ability to induce adipogenesis in stem cells. Indeed, some of them have shown promising activity and are being tested in bovine preadipocytes derived from fat tissue. Maturation of adipose tissue into the typical white adipose tissue takes 2–3 months, much longer than muscle cells need to mature. However, with the goal of mimicking the entire tissue, adding fat tissue is mandatory. In addition to flavor, fat tissue contributes to the texture of meat. The proof-of-concept hamburger lacked fat and as a consequence had a dry mouth feel according to the limited number of tasters.

Like taste, texture or mouth feel is also the result of multiple features of meat, including tissue composition, microscopic and macroscopic tissue architecture, and ability to retain water and fat when cooked.

The formation of small pieces of muscle, such as in hamburgers or other forms of processed meat relies on the innate tendency of muscle cells and fibers to self-assemble in the previously mentioned matrix or scaffold. Histologically, the alignment and distribution of such self-assembled mature muscle fibers look very similar to muscle fibers in vivo. The bundles are maximally 1 mm in diameter and 2.5-cm long with a distinct perimuscular fibrous sheet, resembling perimysium. The secondary structure of these bundles in larger bundles and eventually a full thickness muscle however cannot be formed on the basis of self-assembly alone. Such a tissue, a steak in principle, would require additional technology to provide the macroscopic architecture of the tissue, but more importantly it would need to contain a perfusable channel system to carry oxygen and nutrients into the tissue's center. The technologies to make those structures do exist but have not been applied yet to meat and will require substantial development.

The tissue-engineered muscle fibers have cross-striations, strongly suggesting that sarcomeres with appropriate actin and myosin complexes have formed.

Other cells may be required to accomplish full mimicry of meat. Skeletal muscle as our most metabolically active and oxygen demanding tissue during exercise is a highly vascularized tissue, mostly in the form of capillaries capable of gas and nutrient exchange. It seems unlikely on the basis of the small contribution of vascular cells to the total protein content of muscle that the vasculature contributes appreciably to taste or texture of meat. However, it is possible and even likely that vascular cells influence the maturation of skeletal muscle cells through paracrine activity. As an example, it has been shown that endothelial products enhance proliferation of skeletal myoblasts in vitro (Christov et al., 2007). Likewise, in heart muscle, enhanced neovascularization induces hypertrophy through paracrine effects involving a nitric oxide–dependent pathway (Tirziu et al., 2007).

The same might be true for neural cells. In vivo, muscle is innervated by sensory and somatic nerve cells that keep muscles in a state of continuous activity. Tissue engineered skeletal muscle spontaneously generates motor neuron endplates, but displays much more of these structures when myoblasts are cocultured with glial cells (Vianney and Spitsbergen, 2011). As a result, force generation of the artificial muscle upon electric stimulation is greatly increased.

Mutual interaction through a paracrine pathway or cell–cell contact might also exist between fat cells and skeletal muscle, providing an additional motivation to add fat tissue to the muscle.

Coculture of cells is experimentally challenging because the number of test conditions rapidly increase with increasing number of cell-types. It is also a technical challenge as most cell-types are specific in their nutritional needs. Finding the optimal medium and the optimal time to introduce new cell types in the culture requires extensive testing. However, if most cell interactions are in fact based on paracrine influences, the factors involved might be isolated and used without using the original cell source in coculture.

Sensory experiments including tasting panels will finally determine the success of mimicry. To feed these tasting panels, production needs to be scaled up.

Finally, recreating muscle tissue in all of its complexity may not be sufficient if the aging process after death of the tissue is not similar to livestock meat. Regarding aging of conventional meat, a long storage time of beef (at least 14 days) in cooling conditions is recommended to obtain an acceptable final tenderness and flavor of meat. Many studies have shown that the meat tenderization process is complex and is based on the extent of proteolysis of key target skeleton proteins within muscle fibers and the alteration of muscle structure due the sequential actions of many enzymes. More precisely, after slaughter of farm animals, muscle fibers go into rigor mortis due to protein contraction and the muscle is tough. The extent of this process in the case of cultured beef is still unknown and is likely to be different due to different harvest conditions of the muscle, being just ischemia in cultured meat and a sequence of death-related events in vivo, such as release of catecholamines and stress factors. Subsequently, as the aging process occurs in muscle from farm animals, aerobic metabolism declines with the decreasing oxygen supply and therefore, glycogen is converted into lactic acid inducing a decline in pH to 5.4–5.8. The pH and temperature should decline within a precise window to achieve optimal palatability of meat (Thompson, 2002). It is as yet unknown if this process is reproduced in the ischemic cultured beef. In the case of conventional meat, postmortem protein breakdown is caused by the proteolytic action of different endogenous muscle enzyme groups during carcass storage. However, the importance of the different groups of muscle peptidases in this process is still a matter of controversy. Indeed, the calpain system with its associated inhibitors (calpastatin) was considered to be the primary system responsible for meat tenderization and the action of this system is still under study (Lian et al., 2013). More recently, the onset of apoptosis, which controls the cell death process and the associated degradation of structural proteins, was thought to be important as well, but this process is extremely complex with a great number of molecular actors involved and it is therefore not completely understood (Ouali et al., 2013). Researchers are still working to understand these mechanisms to better predict the quality of conventional meat, and therefore, the only way to reproduce these events is to create a product that is as close a mimic of livestock meat as possible.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780081005934000175

Flavors, Taste Preferences, and the Consumer

S.R. Nadathur , M. Carolan , in Sustainable Protein Sources, 2017

23.5 Introduction of New Foods and Changing Consumer Habits

Current products on the market utilize plant protein concentrates and isolates to replace dairy protein or eggs in traditional or familiar products of Western societies. New-generation meat alternates or substitutes are in development to rival the taste and texture of meat. Clearly, these products will aid in the switch of dietary habits from an animal protein-based diet. Any reduction in meat consumption will also lessen the resources required to produce animal feed including land, water, and energy.

To achieve a major dent in environmental and socioeconomic aspects would entail changes in dietary patterns towards plant-based diets. This presents a transformational opportunity for the current global citizens, especially in Western societies. With a major increase in population causing ever more exploitation of natural resources, it is vital that we reduce meat consumption towards a plant-based diet. Cultures around the globe have been consuming a variety of grains, legumes, seeds, nuts, and vegetables, all of which provide adequate protein, and other vital nutrients and minerals. This consumption occurred for centuries and even had a health connotation. Purifying proteins would also strip away these valuable nutrients while adding cost.

Understanding prevailing cultural influences and learning to overcome neophobic tendencies would create a significant moment in our lifetime to encourage people from around the globe to consume the variety the earth has to offer. Social media can aid in this movement via promotion of recipes and trends, while encouraging the switch to an environmentally friendly diet. People would not only enjoy great foods, but also improve their health and reduce the ill effects of a high-caloric Western diet. This switch would greatly affect land use and rather than growing crops for animal feed, farmers can cultivate them for direct human consumption. Further, fertilizer, water, and fossil energy use will lessen with a consequential reduction in greenhouse gas emission.

Changing food habits is a difficult process and many factors play a role including social, cultural, and neophobic tendencies. Those with a need such as a medical condition, may accept these difficult food choices more readily than if the situation was hypothetical. Typically, beneficial foods are likely to be bitter or have some off-taste associated with them. Though our instincts tell us to avoid bitter foods, they help reduce blood sugar and contain several phytonutrients that boost our ability to fight off diseases (Weill, 2014). In addition, bitter components increase bile secretion, which increases the availability of fat-soluble vitamins.

However, plant-based foods have some disadvantages, which are not unique. Bitterness, off-tastes in purified plant protein, and flatus require explanation for Western diets to change (Kay, 1998). We have discussed options to reduce bitterness in plant protein isolates or concentrates. Protein purification and taste modulation methods are certainly the best options for utilizing these proteins in beverages, bars, and cultured products. However, societies from around the globe have consumed these grains, legumes, and seeds for centuries utilizing a variety of herbs and spices to make tasteful dishes. Introducing and encouraging those foods made from other cultures could be a major initiative, which can wean away the Western societies from a meat-based diet. Although large cities in the United States and Europe are more accepting of these foods, understanding the cultural influences and using demographic changes to create a completely new menu for the next generation would be a prudent choice.

Relative to beans and legumes, which are often associated with flatus, dairy products cause more flatus due to the breakdown of lactose. Though this is natural, most people relate a vegetarian diet to flatus and shy away from consuming them. An option may be to add baking soda to the water during cooking of the beans or to sprout them. Germination or sprouting resulted in the reduction of oligosaccharide level, which is the source of flatulence-causing gas (Jood, Mehta, Singh, & Bhat, 1985). Yet, diets rich in beans, legumes, greens, and grains support health in multiple ways. These sources provide proteins, vitamins, and minerals, which aid the normal functioning of several organs and reduce the incidence of cancer, diabetes, and kidney failure.

The benefits of eating healthy and supporting the environment can be accomplished at the same time. People can be given incentives, lectured, or be part of the discussion to change. Knowing that food is nutritionally beneficial did not influence people to consume them (Wansink & Chan, 2001). During World War II, a study tried to determine the best methods to encourage the inclusion of organ meats in soldier's diets. The discussion-decision method to include organ meat was more influential than a lecture method (Lewin, 1951). Thus, varieties of options need consideration in order to influence people in Western societies to include more plant-based foods. It is also important that those eating more plant-based diets resist the switch to a Western-style diet. Such switches will exacerbate climate change issues and affect their health as well and thereby requiring lots more resource allocation.

Global warming, climate change, reducing meat consumption, are all akin to "someone else's problems." However, shifting eating habits is not an easy task to accomplish. Encouraging people in Western societies to participate via discussion rather than a professorial method is crucial (Wansink, 2002). In addition, recognizing the link between food and cultural habits is very important. Chef Jamie Oliver from the United Kingdom attempted to create a healthier lunch menu for schools in the United States in 2014. He found that changing habits of kids to eat healthy foods requires overcoming resistance. With time, he understood the cultural dimension in that region of the United States, and used incentives to develop better eating among the kids (Von Post, 2011). Changing habits involves providing the background facts so the consumer can make the proper choice, such as the harmful effects of climate change. Behavioral changes are difficult and it will require providing more information on the need to change habits. People do not need to give up meat altogether, but make a decision to reduce consumption to a few times a week rather than daily. There are many other related decisions that can help make the earth a better place, and impact climate change. If many people join in, these reductions can add up to making a meaningful impact. We mean that quite literally: the enrollment of many people. The literature is clear on the effectiveness of when families and communities begin making dietary changes together (eg, Ashida, Wilkinson, & Koehly, 2012). It is a virtuous cycle. People are more likely to adopt new behaviors (and indeed even tastes) when others within their social network do so (Carolan, 2011). That is why, for instance, targeting school-aged kids in schools is so appealing (Mcisaac, Read, Veugelers, & Kirk, 2013). If it were to become "normal" to eat alternative proteins you can bet school-aged children would start eating them at greater rates. Moreover, that ought to be the goal: to reach a point were sustainable protein consumption is the normal thing to do.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780128027783000238

Cryogenic Freezing of Food

Silvia Estrada-Flores , in Reference Module in Food Science, 2016

Introduction

In 2013, the global frozen food market represented a retail value of US$119.9   billion (MarketLine, 2014). This significant market includes sales of products such as:

•

Frozen processed red meat, poultry, and fish/seafood

•

Frozen processed fruit and vegetables

•

Frozen ready-to-eat meals, pizza, and meat substitutes

•

Frozen bakery products

•

Frozen processed potatoes (including uncooked and oven baked)

•

Frozen dessert products (including ice cream)

Cryogenic freezing of food, a technology that has been applied in the food industry since the early 1960s (Almqvist, 2003), is well suited for many of the product categories listed above. Cryogenic freezing refers to the use of expandable gaseous refrigerants such as argon, oxygen, hydrogen, nitrogen, carbon dioxide, and other gases, which evaporate or sublime at very low temperatures at atmospheric pressure. In food manufacturing, the most commonly used cryogenic substances are nitrogen (N2) and carbon dioxide (CO2). The physical and chemical properties of both substances are presented in Table 1.

Table 1. Physical and chemical properties of nitrogen and carbon dioxide

Chemical formula N2 CO2
Molecular weight (kg   mol−1) 28 44
Latent heat (kJ   kg−1) 199.1 (vaporization) 572.3 (sublimation)
Density of vapor at 0   °C (kg m−3) 1.26 1.97
Processing temperature (°C) −195.5 (boiling point) −78.3 (solid)

During a typical cryogenic process, the surface of the product can be exposed to (1) a spray of liquid N2; (2) a mixture of solid ('snow') and gaseous CO2; or (3) a direct immersion into the liquid cryogen. The handling of refrigerant is much simpler than in mechanical refrigeration systems: the cryogenic substance (or cryogen) is usually delivered to the food manufacturing plant as a high-pressure liquid. The options for delivery vary, although the most common means include liquid-filled cylinders or road tankers that deliver bulk quantities of the liquid cryogen to an on-site storage system. This storage system must be insulated or refrigerated. Piping is used to transport the cryogenic liquid to the freezer, where an arrangement of nozzles and valves spray the substance into an insulated tunnel transporting the product to be treated. The different thermal properties of N2 and CO2 determine the specific design parameters required for food freezing (Cleland and Valentas, 1997; North and Lovatt, 2006; Kennedy, 2008).

The often cited benefits of cryogenic freezing have been summarized elsewhere (Estrada-Flores, 2012) and include:

•

Fast cooling/freezing rates, leading to a higher quality of frozen products as compared to slower freezing methods

•

High efficiency and productivity, and a relatively simple operation

•

Reduction of food safety risks

•

Low setup and maintenance costs

•

Low energy consumption during freezing

•

Modest requirements of floor space for installation

However, there are also some disadvantages associated with cryogenic freezing, such as higher operating costs as compared to mechanical refrigeration systems (Chourot et al., 2003). Further, cryogenic freezing is better suited to small- or medium-sized products, or products that have a large surface area. In large products with limited surface area, the rate of freezing – which is a key advantage in cryogenic freezing – is limited by the rate of internal heat transfer (Cleland and Valentas, 1997). Cryogenic freezing suits small-scale production, new or seasonal products that require fast freezing, and situations where the installed freezing capacity cannot cope with production throughput demands (ASHRAE, 2006).

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780081005965031759

Potato proteins

A.C. Alting , ... N.H. van Nieuwenhuijzen , in Handbook of Food Proteins, 2011

12.6.4 Gelation properties

Both the patatin and the Solanic LMW fractions can form a gel under specific conditions (Creusot et al., 2010; Giuseppin and Bakker, 2008 ). The gel formation properties of potato proteins can be used in applications such as brine injected meats, surimi or vegetable meat substitutes. The denatur-ation temperature of patatin is approximately 20  °C lower compared to those of other food proteins such as ovalbumin, soy glycinin and beta-lactoglobulin. However, the gelling behaviour of patatin, with respect to ionic strength and protein concentration, was quite similar to those of ovalbumin and beta-lactoglobulin (Fig. 12.3). The LMW fraction gelled most effectively at a low pH (<   pH   4.5) and with some salt added (more than 0.35% NaCl). A gel could still be obtained at higher concentrations (12% protein) at a pH of 5.4 (highest pH tested) (Giuseppin and Bakker, 2008).

Fig. 12.3. Storage modulus G' after completion of the temperature programme as a function of protein concentration of gels formed at pH   7.0, in water (a) and in 100   mM NaCl (b). The lines are guides to the eye. Vertical lines indicate the minimum gel concentration of the proteins.

 From Creusot et al. (2010)

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9781845697587500125

Fermented Foods: Use of Starter Cultures

P.M. Malo , E.A. Urquhart , in Encyclopedia of Food and Health, 2016

Removal of Antinutritional Factors

Fermentation is known to remove a number of harmful and toxic compounds from foods by several means of detoxification. Most notably, fermentation increases the nutritive quality of plant foods by metabolically reducing certain types of antinutrients found in foods such as cyanide, phytic acid, and oxalic acid. For example, the fermentation process that produces kawal, a Sudanese meat substitute, removes harmful toxins from cassava leaves, ensuring them safe for human consumption. Phytates, or phytic acids, are the phosphorus-bound organic acids that protect grains, beans, nuts, and other seeds from premature germination and are well-known antinutrients that can cause mineral deficiencies and digestion issues over time. Common health effects of a phytate-rich diet include tooth decay, lack of appetite, digestive problems, and nutrient deficiencies. For regular consumption of phytate-containing foods in the absence of negative health effects, it is necessary to remove the phytates and other antinutrients through processing techniques such as sprouting, soaking, and fermenting.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780123849472002828