Fermented food products

Dairy Products Meat Products Fish products Vegetable products Legume products Organic acids

Fermented meat products Sausages are one of the oldest form of foods consumed by humans. The manufacture of sausages began over two thousand years ago, and it is still a growing industry. While some of its basic practices are almost as old as civilization. In olden days people did not have refrigeration to preserve their meat and so making sausage was a way of overcoming this problem

History Dry sausage was born as a result of the discovery of new spices, which helped to enhance, flavour and preserve the meat. Different countries and different cities within those countries started producing their own distinctive types of sausage, both fresh and dry. These different types of sausage were mostly influenced by the availability of ingredients as well as the climate. Some parts of the world with periods of cold climate, such as northern Europe were able to keep their fresh sausage without refrigeration, during the cold months. They also developed a process of smoking the sausage to help preserve the meat during the warmer months. The hotter climates in the south of Europe developed dry sausage, which did not need refrigeration at all.

Basically people living in particular areas developed their own types of sausage and that sausage became associated with the area. For example Bologna originated in the town of Bologna in Northern Italy, Lyons sausage from Lyons in France and Berliner sausage from Berlin in Germany, in England they became associated with the county's, Berkshire, Wiltshire, Lincolnshire, Cumberland Etc. In practice for over a millenia sausage-making was originally a method used to preserve meats, especially lesser cuts. History

Dry and semi-dry sausages Fermented dry sausages are defined as chopped or ground meat products that, as a result of bacterial action, reach a pH of 5.3 or less and are then dried to remove 25–50% of the moisture, resulting in a moisture-to-protein ratio no greater than 2.3:1.0. Semidry fermented sausages, which are the same that the moisture level is decreased by 15%, are packaged soon after the completion of the fermentation–heating process. They are generally smoked during fermentation, and the moisture-to-protein ratio must be no greater than 3.7:1.0

ClassMoistureCharacteristicsExamples Dry sausages25 to 45 percentCured, air-dried, sometimes smoked, mold-ripened Pepperoni, Genoa salami Semi dry sausages40 to 50 percentCured, air dried, usually smokedLebanon bologna, summer sausage Fresh smoked sausage Fresh meat, cured or uncured; smoked, not cooked; must be cooked prior to consumption Country style Mettwurst Kielbasa Cooked sausageCured or uncured; cooked and smoked Frankfurters Bologna

Meat sausage production process Ingredients (%) of dry and semidry fermented sausages are Lean meat (pork, beef) 55–70 Fat 25–40 Curing salts ∼ 3 Fermentable carbohydrate 0.4–2 Spices, flavorings ∼ 0.5 Other: starter culture, ascorbic acid, nitrite ∼ 0.5

Processing of sausages The manufacture of dry and fermented sausages proceeds as follows. The meat is formulated by breaking (i.e., grinding, chopping, and mixing) with the fat, to give the desired fat content. This is done at cold temperatures to avoid smearing the fat. The spices, flavorings, curing salts, carbohydrate, nitrite, and starter culture are mixed in, and the mixture is stuffed into the proper sausage casings (cellulose, collagen, or natural) at a temperature of −2.2 to 1.1 ∘ C. Maturation

STARTER CULTURES The normal inoculum level (≈106 organisms per gram of product) theoretically inhibits any growth of undesirable microorganisms The following starter culture characteristics are ideal for sausage production: salt tolerance, fast growth, nitrite tolerance, optimum temperature for growth is ∼ 32 ∘ C, and the culture should be homofermentative, nonproteolytic, nonlipolytic, nonpathogenic, nontoxic, and with no off-flavor production. An inactivation temperature of ∼ 60 ∘ C is most desirable. (Kongkiattikajorn, 2013)

Maturation of sausages The environmental conditions can vary widely during fermentation depending on the type of sausage being made. Traditionally, the temperature can range from 15.6 to 23.9 ∘ C and the relative humidity from 80% to 90%. The temperature is raised over the course of fermentation: for dry sausages, up to 37.8 ∘ C; for semi-dry sausages, up to 43 ∘ C. The nature of the fermentation will depend on which microorganisms are present. The dominant microorganisms in most sausages are Lactobacillus spp., which are generally homofermentative in that they produce only lactic acid as a product that gives the characteristic tangy flavor. Heterofermentative microorganisms can produce an assortment of end products including lactic acid, ethanol, carbon dioxide, and acetic acid, which can add to the uniqueness of a sausage; or they can be unwanted, depending on the type of product. Following fermentation, sausages are fully cooked, partially cooked, and/or placed in a drying room. Fermentation may continue during this process depending on the growth characteristics of the particular bacteria, temperature, pH, carbohydrate level, and degree of heat penetration.

Fermented Milk Products Yogurt is made with Streptococcus thermophilus and Lactobacillus delbrueckii subsp. Bulgaricus. Buttermilk is made with lactobacillus spp. Without or with Leuconostoc cremoris. Acidophilus milk is made from Lactobacillus acidophilus.

Yoghurt : a fermented dairy product Plain yogurt has a semisolid mass due to coagulation of milk(skim, low, or full fat) by starter culture bacteria. It has a sharp acid taste with falvor similar to walnuts and a smooth mouth feel. The flavor is due to combined effect of acetaldehyde, lactate,diacetyl and acetate. About 90% of flavor is due to acetaldehyde.

Processing of yoghurt Batch process for a low fat 2% plain yogurt Homogenized milk (12% TS) plus stabilizer (1%), the stabilizer is added to give desired gel structure. Heating to 85C for 30 min, and cooled to 43.3C, heating helps to destroy vegetative microbes and slightly destabilize casein for good gel formation. Starter is added, incubated at 43.3C and pH 4.8 for 6h. Quickly cooled to 29.4C for 30.min. to slow down further starter growth and acid production especially by Lactobacillus spp., agitated and pumped to filler machine. Packaged in containers, cooled by forced air to 4.4C to stop the growth of starter. Held for 24h, pH drops to 4.3.

Starter culture for yoghurt In a good product, the two starter species should be added at a Strep:Lacto ratio of 1:1, in the final product, the ratio should not exceed 3:2. For balanced growth of the two species, the fermentation is conducted at 43.3C, at this temperature both acid and flavor compounds are produced at the desired level. If the temperature is raised above 43.3C lactobacillus spp. Predominates, causing more acid and less flavor production. At temperature below 43.3C growth of Streptococcus spp. is favored, forming a product containing less acid and more flavor

Contd….. The two species show symbiotic growth while growing together in milk. Initially Streptococcus spp. Grows rapidly in the presence of oxygen and produces formic acid and CO2. The anaerobic condition, formic acid and CO2 stimulate growth of lactobacillus spp. Which has good exoproteinase and peptidase systems and produce amino acids and peptides from milk proteins. Some of the amino acids such as glycine, valine, histidine, leucine and methionine are necessary for good growth of Streptococcus spp. Which lacks proteinase enzymes. Streptococcus spp. Grows rapidly until pH drops to 5.5 at which time the growth of Streptococcus spp. slows down. However, growth of Lactobacillus spp. Continues fairly rapidly until the temperature is reduced to 29.4C following a drop in pH to 4.8

Fermentd soy products Why to ferment soya? Soy iso-flavones can lead to breast cancer Soy iso-flavones have a direct correlation with increased thyroid disease. Iso-flavones are a type of phytoestrogen, which is a plant compound resembling human estrogen, that have been found to have adverse effects on various human tissues Soy phytoestrogens are known to disrupt endocrine function, may cause infertility, and may lead to breast cancer in women.