Cultured meat has been presented earlier as one of the newest alternatives to livestock meat. This alternative has been proposed as a more sustainable source of meat than livestock, although the environmental impact of large-scale cultured meat production is still unclear. Cultured meat has been estimated to reduce land use by 99% for its production compared to livestock meat production. Nevertheless, other energy needs and a strict hygiene installation required for the production of cultured meat makes it inefficient in terms of energy, water and feedstock expenditure ^[5]. Energy cost and CO₂ derived from cultured meat production has been estimated to be worse than cattle in the very long term ^[6], as long as we continue to use carbon-based energy sources.

An important innovation in this alternative is the capacity to alter the nutritional profile of the meat by altering the medium. This can be done by adding nutrients, for example vitamins, or modifying the fatty acid profile of the meat. Co-culturing the cells with adipocytes could increase tissue fat and therefore help modify the flavor of the final product ^[7].

Therefore, cultured meat is a promising alternative for its nutritional and sensory properties, further investigation is warranted to reduce the energy costs and environmental impact cultured meat currently requires for its production.

The main challenges of milk alternatives are to provide a desirable and acceptable sensory experience for consumers and to match the nutritional value of milk. To compensate for possible nutritional deficiencies, fortification with vitamins and amino acids is applied to these products. Furthermore, fermentation of milk alternatives improves sensory perception because it decreases the beany flavor of plant materials and provides desirable volatile flavors ^[8]. The addition of a starter culture to plant-based beverages is also used in the production of vegan or plant-based yogurts. Probiotic strains can be added to soy-based yogurts, and these strains can compete better with starter cultures in a soy beverage than in cows’ milk^[9].

Fermentation with two or more microorganisms can improve plant protein solubility and amino acid composition and availability. For example, Bifidobacterium significantly increased the protein content of soy-based drinks. Moreover, fermentation of soybean with Lactobacillus plantarum resulted in an increase of essential amino acids such as lysine. Furthermore, co-fermentation of peanut using Lactobacillus acidophilus and Lactobacillus plantarum significantly increased the total protein and lysine, methionine and tryptophan contents compared to those of the corresponding mono-culture fermentations. Spontaneous co-fermentation of strains originating from cowpea and chickpea improved methionine levels. However, in other cases, mixed-culture fermentation appeared inferior to mono-culture processes ^[8].

In Asia, cheese analogs have been around since the 1500s. Fermented tofu has been used as a substitute because its strong aroma reminds of mold-ripened cheeses like Roquefort or Camembert. Although, it does not melt, it can be easily spread. To produce this alternative cheese, tofu cubes are inoculated with a special mold and left to ripe in a warm environment to let the mycelium grow ^[10].

In Western countries, the production of cheese analogs involves the use of fat and/or protein sources other than those from cow’s milk, together with flavors that resemble as closely as possible those of the original product. It is important to note that cheese analogs can completely exclude milk and milk products (vegan) or partially contain milk or milk components (e.g., casein, butter oil, etc.) together with coconut or soybean extract^[11]. In cheese analogs, the milk protein and milk fat are partly or totally replaced by vegetable proteins (i.e., peanut protein, soybean protein) and vegetable fats and oils (i.e., partly hydrogenated vegetable fat like soybean, palm, etc.). Cheese analogs have been consumed for decades, mainly used in pizza as cheaper alternatives to cut production costs. Still, the difficulties of reproducing the unique flavors of different types of cheese is what has prevented the use of cheese analogs as “cheese board” products for many years ^[11].

In recent years, innovations in vegan cheese recipes and preparation methods have greatly improved the sensory properties of these products. Soy, nuts, coconuts, tapioca, and even potatoes are used to prepare them. Vegan Parmesan cheese can be prepared grinding nuts and nutritional yeast together. Cashews can be soaked in rejuvelac (fermented grain beverage) to obtain vegan Mozzarella ^[12]. Arrowroot and cassava have also been used to make commercial vegan cheese because they provide melting and stretching properties, which are hard to replicate without casein^[13].

Egg alternatives are used instead of eggs in recipes by consumers following a vegan diet or individuals with egg allergy. While other products such as meat alternatives aim to replicate the sensory qualities and experience of consuming the original product, the main objective of the egg alternative is to replace the functional properties of egg protein (solubility, emulsification, foaming and gelling) for backing and cooking. “Vegan mayonnaise” is the most tested product in studies on the effectiveness of vegetable ingredients to substitute the egg’s properties. Preparation of cholesterol-free and modified lipid versions of such products is also of interest.

Söderberg ^[14] investigated the use of soy and pea protein to substitute egg protein and found that both soy and pea protein have properties that are similar to that of egg, although pea protein showed poor gelling properties. Furthermore, according to the protein digestibility-corrected amino acid score (PDCAAS), soy was found to have similar protein quality to egg, but pea protein was found to be incomplete. In order for pea protein to become complete, the complementarity concept in terms of amino acid composition between different plant protein sources may be used. Another aspect that should be taken into account is that soy and pea protein have distinct flavors due to their content in saponins, ketones and aldehyde compounds. These flavors are often described as “beany” or “green” and can be off-putting to the consumer.

Garcia et al. ^[15] formulated a mayonnaise containing rice bran oil and soy protein concentrate which received an overall low acceptance rating among consumers. Only after further flavors were added acceptance increased considerably. In addition, the intent to purchase significantly increased when consumers were informed of the potential benefits of the new formulation.

Vegan mayonnaise has also been prepared using soy milk, xanthan gum and guar gum as stabilizers^[16] and using arabic gum alone^[17]. Other vegetable proteins from soy, sunflower, pea, tomato seed, wheat, white lupin and faba bean have been successfully tested to stabilize oil-in-water emulsions ^[16]. To substitute eggs in baking and cooking, ingredients as varied as apple sauce, aquafaba, flax seeds, tofu, ripe bananas and tapioca starch can be used ^[18]. Although there is an ample list of ingredients that can emulate eggs when cooking, the nutritional value of these ingredients must be taken into account. Protein rich foods like legumes can offer similar protein content, while other ingredients contain only marginal protein. If protein content differs notably, consumers must be mindful to avoid nutritional deficiencies from regular consumption of egg alternatives with insufficient protein content.

Microalgal biomass has been consumed by the indigenous populations to survive during extreme food shortages as, depending on the species, can contain up to 70% protein or 40% of marine oils^[19]. Protein of algae contains all essential amino acids, with some species showing comparable amino acid profiles to soybean and eggs. However, digestibility and bioavailability are also major factors as the cell wall interferes in the utilization of nutrients. To increase bioavailability of microalgae proteins a pretreatment can help disrupt the cell wall^[20]. Schizochytrium sp is a good source of the omega-3 fatty acid DHA and its oil mechanically extracted has been accepted as a new food by the EFSA ^[21]. This can be included in infant formula, follow-on formula and other products.

Common fish alternatives are made with tofu and seitan (wheat gluten) to which soy sauce, miso paste or algae are added to provide the sea-like taste. Furthermore, some microalgae are sustainable sources of protein while others are sources of omega-3 and could contribute to the dietary intake of EPA and DHA ^[20].

The issue with some current fish alternatives is that they do not provide any of the nutritional benefits of fish and seafood consumption. In this regard, neither tofu nor seitan are sources of EPA and DHA, and other fish alternatives made from vegetables do not provide protein or omega-3 FAs. In vegan and vegetarian recipes, mushrooms are sometimes used as substitutes for seafood, peeled and marinated tomatoes and carrots have been proposed as marinated tuna, and salmon, respectively. Although these are clever imitations that emulate sensory properties, they should be improved to achieve an adequate nutritional profile.

3. Conclusion

The number of consumers who are reducing their intake of food from animal origin is increasing globally due to many reasons and this involves a growing market of plant-based products. Consumers demand products that are sustainable, palatable, safe, nutritious, available, and affordable. Therefore, many issues should be considered when planning new sources and ingredients. On the other hand, plant-based diets present health opportunities such as reduced risk of diabetes and cardiovascular diseases. Finally, being aware of protecting the planet means that plants, animals and humans are part of it and a healthy planet should be compatible with a healthier human being.