Fermentations starter cultures

The effect of complex commercial fermentation activators on biogenic amine production was tested by Marques et al. (2008). On the whole, it does not seem that complex nutrient preparations produced for the use with fermentation starter cultures pose a serious threat to biogenic amine production in wines. 

Foods that include the incorporation of microbial metabolites as part of their production are an intricate component of the world s food supply and for ethical and sensory-nutritional reasons it is essential for all the world s population to have access to this form of food. It is a process that has been in use since the early history of mankind. An Egyptian pot dating from 2300 BC (McGee, 1984) was found to contain residues of cheese and in passages in the Bible the use of some kind of fermentative starter culture is indicated. It is, therefore, possible that the use of bacteria such as the lactic acid bacteria (LAB) dates back at least four to five thousand years, although the exact principle behind the process may not have been known to the civilizations of those times (Davidson et al., 1995). Production of fermented foods, where organisms such as the LAB are involved, is a technological process that has been used for centuries at least (Herreros et al., 2005). 

Lerm, E., Engelbrecht, L., du Toit, M. (2011). Selection and characterisation of Oerwcoccus oeni and Lactobacillus plantarum South African wine isolates for use as malolactic fermentation starter cultures. South African Journal for Etiology andViticulture, 32,280-295. 

Massawe, G. A., Lifa, S. J. (2010). Yeasts and lactic acid bacteria coffee fermentation starter cultures. International Journal of Postharvest Technology and Innovation, 2,41-82. 

Biomass is used for four purposes as a source of protein for human food or animal feed, in industry as fermentation starter cultures, in agriculture as a pesticide or fertilizer, and as a fuel source. 

The use of fermentation to preserve and improve the properties of food has a long history. For example, milk has been preserved by fermentation for at least seven millennia (Dunne et ah, 2012). Initially, fermentation was a spontaneous process, probably with mixed results, and it was quickly learned that inoculation of the material to be fermented with a suitable inoculum would increase the likelihood of success. Traditionally, this was done by using part of a previous fermentation as an inoculum, but as microbiological knowledge increased, inoculation with specifically prepared fermentation starter cultures developed (Hpier et al., 2010). This in turn gave a better control of the fermentation process and allowed for the development of new products with novel properties. This is well illustrated in the dairy industry, where a diversity of bacterial species is used to manufacture a large variety of fermented dairy products (Table 10.1). 

Commercially available yeast extracts are made from brewers yeast, from bakers yeast, from alcohol-grown yeast (C. utilis) and from whey grown yeast (K fragilis). Extracts are used ia fermentation media for productioa of antibiotics, ia cheese starter cultures, and ia the productioa of viaegar. They are also exteasively used ia the food iadustry as condiments to provide savory flavors for soups, gravies and bouillon cubes, and as flavor intensifiers ia cheese products. 

To ensure the safety of food products, representative samples must be inspected so that foodborne bacteria can be identified.15,18,19 Bacteria producing heat-stable enterotoxins, such as Staphylococcus aureus, may be identified by biochemical and serological techniques.20,21 Molecular methods are now widely used for the identification of many pathogenic foodborne bacteria,15,22,23 In addition bacteria used as starter cultures for cheese, yogurt, other fermented foods and beverages, and probiotic dietary supplements may be identified for quality assurance.22,24,25... 

The upstream processing element of the manufacture of a batch of biopharmaceutical product begins with the removal of a single ampoule of the working cell bank. This vial is used to inoculate a small volume of sterile media, with subsequent incubation under appropriate conditions. This describes the growth of laboratory-scale starter cultures of the producer cell line. This starter culture is, in turn, used to inoculate a production-scale starter culture that is used to inoculate the production-scale bioreactor (Figure 5.7). The media composition and fermentation conditions required to... 

Fermentation follows for several days subsequent to inoculation with the production-scale starter culture (Figure 5.7). During this process, biomass (i.e. cell mass) accumulates. In most cases, product accumulates intracellularly and cells are harvested when maximum biomass yields are achieved. This feed batch approach is the one normally taken during biopharmaceutical manufacture, although reactors can also be operated on a continuous basis, where fresh nutrient media is continually added and a fraction of the media/biomass continually removed and processed. During... 

Hernandez-Jover, M., Izquierdo-Pulido, M., Veciana-Nogues, M.T., Marine-Font, A. and Vidal-Carou, M.C. (1997). Effect of starter cultures on biogenic amine formation during fermented sausage production, J. Food Prot., 60, 825. 

Komprda, T., Neznalova, J., Satndara, S. and Bover-Cid, S. (2001). Effect of starter culture and storage temperature on the content of biogenic amines in dry fermented sausage polican. Meat Sci., 59, 267. 

Table 10.12 Some typical examples of starter cultures employed in the manufacture of fermented milks (from Robinson and Tamime, 1993)...

Apart from public health impacts, residual antimicrobials in animal products can bring about technoeconomic losses in the food processing industry. It has long been known that the presence of some antimicrobial compounds in milk can dramatically affect the production of fermented dairy products such as yogurt, cheese, buttermilk and sour cream (72, 73). As shown in Table 10.2, even minute concentrations of antibiotics in milk can cause inhibition of the growth of commonly used dairy starter cultures (74). 

The efficiency of using starter cultures is in dispute. Rankine and Pilone (54) have found no consistency in the rate of completion of malo-lactic fermentation in relation to the amount of inoculum used or the time of addition. Indeed we, and others, also have found from time... 

We have found a high degree of correlation between induction of rapid malo-lactic fermentation and bacteria addition in starter cultures when the wines were treated as suggested above to encourage the fermentation. Peynaud and Domercq (51) obtained malo-lactic fermentation by inoculating commercial wines of a locality which had not had a natural fermentation for many years. 

Malo-Lacttc Starter Culture. This must be monitored with great care and precision. Most California wineries don t use Leuconostoc starter cultures for malo-lactic fermentations because the organisms are generally so unpredictable and difficult to control. Where used, in the cooler coastal areas, the results are worth the effort, but it must be stressed that this is not for amateurs. Precise control is absolutely essential. See Pilone and Kunkee (10), Tchelistcheff et al. (II), and earlier papers by Kunkee. 

White wines are normally fermented in containers that can be partially closed so that the surface of the fermenting wine is protected from the air by a blanket of carbon dioxide. For the home winemaker, 5-gallon carboys serve admirably. An hour or so after adding S02, one adds approximately 3% of an actively fermenting pure-culture starter yeast. 

The calculated amount of S02 is added and mixed thoroughly with the grapes, and the opening of the vessel is covered with a cloth to prevent the entry of insects. After 2-4 hrs the pure-yeast starter culture is added—again with stirring so that there is thorough mixing. The cloth cover is replaced. Active fermentation will be apparent within a day or so. 

The most important fermentative reaction used in dairy processing is the homofermentative conversion of lactose to lactic acid. The efficient manufacture of high-quality cultured products, including most cheese varieties, yogurt, and cultured buttermilk, requires a rapid and consistent rate of lactic acid production. Lactic acid helps to preserve, contributes to the flavor, and modifies the texture of these products. Nearly all starter cultures used to produce acidified dairy products contain one or more strains of lactic streptococci, because these organisms can produce the desired acidity without causing detrimental changes in flavor or texture. Strains of lactic streptococci can be classified as... 

Small amounts of hydrogen peroxide in raw milk can activate the lactoperoxidase-catalyzed oxidation of thiocyanate to produce a bacterial inhibitor (Hogg and Jago 1970). Inhibitory compounds resulting from oxygen metabolism can produce initially slow starter culture growth in industrial dairy fermentations if the milk has been excessively agitated. 

Cultured dairy foods seldom cause foodborne illness in the consumer. If an active starter culture is used, common foodborne pathogens, even if present in the milk, do not grow well and often are inactivated during the fermentation or early during the storage life of the product. Even if some cultured products are recontaminated after manufacture, pathogens generally do not survive well. Several examples will illustrate these points. 

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