Table 1.

Methods and processing operations used to obtain functional foods.

Methods/Processing Operations	What Involves	Products	References
Technological methods/operations
Fortification or enrichment	This method involves adding specific nutrients or bioactive compounds with low nutritional values to a food product, during osmotic dehydration, hydration, and cooking or using pretreatment. However, their bioavailability, stability, or nutrient location in food are scarcely analysed.	cereals, dairy products, flour, condiments	[25]
Fermentation	Fermentation is a natural safe technique for food preservation that enhances the bioavailability and digestibility of nutrients in foods, which are rich in probiotics and beneficial microorganisms. The most common fermentations are lactic acid homofermentation and heterofermentation, butyric acid, mixed acid, propionic acid, and acetic acid.	yogurt, kefir, and sauerkraut; beans, legumes, flours, and some cereals	[26]
Sprouting	Sprouting seeds, grains, or legumes increases their nutrient content, including vitamins, minerals, and antioxidants. This method also increases the digestibility and sensory qualities of sprouts and decreases the levels of anti-nutritional components.	vegetable, fruits, cereals, spices	[27,28]
Extraction	Extracting bioactive compounds from natural sources, like herbs, fruits, or vegetables, to create supplements or functional ingredients for food products.	supplements	[29,30]
Biotechnology	This method allows for the modification of crops to enhance their functional properties, designed to have higher nutrient content or resistance to pests.	genetically modified crops	[31]
Advanced methods/operations
Food processing techniques	Certain food operations, such as freeze-drying or freeze concentration, can preserve the bioactive compounds in foods while removing water, reduction/elimination, or other unwanted compounds, extending shelf-life, and concentrating nutrients.	juices, fruits, jams	[32,33]
Nanotechnology	Nanotechnology is employed to encapsulate and deliver bioactive compounds like vitamins, minerals, or antioxidants in nano-sized particles. This enhances their stability, solubility, and bioavailability, allowing for controlled release in the body.	bakery, pasta, cereal based products	[34,35]
Microencapsulation	This technique involves coating bioactive compounds with a protective layer, typically a food-grade polymer, to prevent degradation during storage and to increase their stability. Microencapsulated compounds can be added to various food products to make them functional.	phytosterols, fatty acids, polyphenols, other bioactives.	[36,37]
Extrusion	Extrusion is a high-temperature, high-pressure process used to modify the structure of foods. It can increase the availability of bioactive compounds, such as by improving the digestibility of proteins or breaking down complex carbohydrates.	cereal based products, flours,	[38]
Spray drying	Spray drying is used to convert liquid bioactive ingredients into powder form while maintaining their functional properties. This method is commonly employed in the production of powdered supplements and fortified foods.	oils, flours, bioactive compounds.	[39]
High-Pressure processing	Is a non-thermal food processing technique that preserves the nutritional and sensory qualities of foods; reduction/elimination of mycotoxins from foods; improvement of emulsifying properties, gelling capacity and formation, and apparent digestibility. It can be used to maintain the bioactive compounds in fresh foods.	juices, tomatoes, carrots and broccoli, fish, meat, egg, cheese	[40,41]
Pulsed electric field processing	This method uses short bursts of electricity to increase the permeability of cell membranes in foods. This method can enhance the extraction of bioactive compounds from plant materials.	eggs, corn, beetroots, bioactive compounds.	[42,43]
Cold plasma technology	Cold plasma treatment can improve the microbial safety and shelf-life of foods while preserving their nutritional content. It is used in the development of functional foods like fruit juices.	juices, nuts, cereals, fruits, dairy products	[44,45]
Membrane filtration	This method uses selective membranes to separate and concentrate bioactive compounds from food sources, such as proteins, peptides, and polyphenols, for use in functional food products.	fruit and vegetable juices	[46]
Ultrasonication	Ultrasonic waves are employed to break down cell walls and release bioactive compounds from plant materials. This method can be used in the extraction of phytochemicals from fruits and vegetables.	grape pomace, cereals	[47]
Ohmic heating	Ohmic heating uses electrical resistance to heat food products uniformly. It is also used to improve the extraction and retention of bioactive compounds in various foods.	seafood and surimi	[48]
Enzymatic hydrolysis	Is a processing operation which involves the use of specific enzymes to break down complex compounds, such as proteins, into smaller, bioactive peptides. This process enhances the bioavailability of nutrients, making them more readily absorbed by the body.	protein hydrolysates, fish peptides, fruit enzyme extracts	[49,50]
Digital methods/operations
3D printing	These innovative methods involve customized food design, digitalized and personalized nutrition, the efficient use of raw material, and expansion of the food material source. This technology was developed to design and manufacture food with defined properties and characteristics, which can be employed in the development of functional foods to fulfil consumer demands for more healthy food.	cereals, pasta, meat, fish products, fruits.	[21,22]
Nutritional methods
Animal nutrition studies	This method focuses on the biology and chemistry of different nutrients, minerals, bioactive compounds, and feed additives related to animal health and the production of animal products with enhanced qualities.	poultry, dairy, pork products	[14,20,51]