http://sgpwe.izt.uam.mx/files/users/uami/acym/articulo_1.pdf

Food fermentations: Microorganisms with technological beneficial use

More than half of the world populations are affected by micronutrient malnutrition and one third of world’s population suffers from anemia and zinc deficiency, particularly in developing countries. Iron and zinc deficiencies are the major health problems worldwide. Phytic acid is the major storage form of phosphorous in cereals, legumes, oil seeds and nuts. Phytic acid is known as a food inhibitor which chelates micronutrient and prevents it to be bioavailabe for monogastric animals, including humans, because they lack enzyme phytase in their digestive tract. Several methods have been developed to reduce the phytic acid content in food and improve the nutritional value of cereal which becomes poor due to such antinutrient. These include genetic improvement as well as several pre-treatment methods such as fermentation, soaking, germination and enzymatic treatment of grains with phytase enzyme. Biofortification of staple crops using modern biotechnological techniques can potentially help in alleviating malnutrition in developing countries.

Reduction of phytic acid and enhancement of bioavailable micronutrients in food grains.

Fermented foods represent on average one-third of total food consumption. Tempe is a major fermented soyabean food and is known for its attractive flavour, texture and superior digestibility. This present review aims at providing an overview of literature data from ca 1990 until present. Although traditional preparation methods are still applied at the small scale, commercial production at small and medium industrial scale have resulted in technical innovations for improved control of starters and fermentation conditions. Nevertheless, the monitoring, control and modelling of the tempe fermentation at a large scale still presents a big challenge to process engineers. The complex dynamics of the microbiological composition continuously result in new aspects being resolved including the production of enzymes and bioactive compounds. The use of tempe in food consumption has evolved from the stages of basic nutrition to the development of derived products such as burgers and salads, and in recent years health benefits are becoming an important drive for its consumption.

Tempe fermentation, innovation and functionality: update into the third millenium

Phytases decompose phytate, which is the primary storage form of phosphate in plants. More than 10 years ago, the first commercial phytase product became available on the market. It offered to help farmers reduce phosphorus excretion of monogastric animals by replacing inorganic phosphates by microbial phytase in the animal diet. Phytase application can reduce phosphorus excretion by up to 50%, a feat that would contribute significantly toward environmental protection. Furthermore, phytase supplementation leads to improved availability of minerals and trace elements. In addition to its major application in animal nutrition, phytase is also used for processing of human food. Research in this field focuses on better mineral absorption and technical improvement of food processing. All commercial phytase preparations contain microbial enzymes produced by fermentation. A wide variety of phytases were discovered and characterized in the last 10 years. Initial steps to produce phytase in transgenic plants were also undertaken. A crucial role for its commercial success relates to the formulation of the enzyme solution delivered from fermentation. For liquid enzyme products, a long shelf life is achieved by the addition of stabilizing agents. More comfortable for many customers is the use of dry enzyme preparations. Different formulation technologies are used to produce enzyme powders that retain enzyme activity, are stable in application, resistant against high temperatures, dust-free, and easy to handle.

Biotechnological production and applications of phytases

One stop mycology

Forty-six strains of tempe-forming Rhizopus species were screened for their ability to grow on raffinose as the sole carbon source. Six of the strains showed good growth and sporulation. These isolates were one Rhizopus oligosporus, one Rhizopus microsporus var. chinensis, three Rhizopus oryzae and one Rhizopus stolonifer. These six moulds and R. oligosporus strain NRRL 2710 were investigated for their metabolism of the raffinose family of α-galactoside carbohydrates. Degradation experiments were performed in submerged culture in a medium containing soybean α-protein, sodium phytate and either stachyose, raffinose or melibiose. R. oryzae and R. stolonifer completely consumed the tested carbohydrates as carbon source. R. microsporus var. chinensis failed to hydrolyse the α-galactosidic bonds of raffinose, stachyose or melibiose, whereas it was able to use sucrose and the fructose moiety of raffinose or stachyose for growth. R. oligosporus NRRL 2710 was unable to hydrolyse any of the tested carbohydrates. The results of the oligosaccharide degradation experiments could be verified during tempe production from soybeans with the selected fungal species.

H. Rehms

Papers

Degradation of stachyose, raffinose, melibiose and sucrose by different tempe-producing Rhizopus fungi.