Research Tools and Methods for the Analysis of Microbiota in Dairy Products

Microorganisms play important roles in dairy products. They can be a source of spoilage, or they promote health or cause diseases. In dairy fermentations, microorganisms are of great importance due to their function as starter cultures and during the production process of dairy products. In order to better understand and improve the process, it is essential to identify the species that are involved and to monitor the development of microbial communities. There are several different approaches for the detection and analysis of the microbiota. The methods can be culture dependent and, for example, make use of morphological and physiological characters or DNA sequencing. Culture-independent methods include direct PCR and qPCR, but also electrophoresis-based profiling techniques as well as metagenomics. Descriptions of relevant methods are provided and their applications are discussed in this chapter.

Role of Microbial Cultures and Enzymes During Cheese Production and Ripening

Many different kinds of cultures, enzymes, and methods are used during the production and ripening of a variety of cheese types. In this chapter, the importance, types, and applications of microbial cultures during cheese production are discussed. Moreover, an overview of the important role of enzymatic systems, either derived from these cultures or directly added to the milk fermentation, is presented. The main biochemical events including glycolysis, lipolysis, and proteolysis during cheese ripening are explained, focusing on their end products, which contribute to the development of the overall aroma of cheese.

The Effects of Probiotic Cultures in Functional Foods

Functional foods are an important part of an overall healthy lifestyle that includes a balanced diet and physical activity. The consumption of probiotic foods has many benefits. Dairy products that contain probiotic bacteria are those that are produced with various fermentation methods, especially lactic acid fermentation, by using starter cultures and those that have various textures and aromas. Fermented dairy probiotic products are popular due to their differences in taste and their favourable physiological effects. However, recent upsurge in interest of consumers towards dairy alternatives has opened up new research areas for developing non-dairy probiotic products. Different substrates such as cereals, fruit juices, vegetables can be used utilized for delivering these beneficial microorganisms. This chapter provides an insight on the recent research/developments about selection criteria of bacteria as probiotics and in the field of technological properties of probiotics.

Potential Probiotic Microorganisms in Kefir

Probiotic microorganisms are defined as living microorganisms that provide health benefits on the host when administered in adequate amounts. The benefits include improvement of microbial balance immune system and oral health, provision of cholesterol-lowering effect, and antimicrobial activity against a wide variety of bacteria and some fungi. Kefir microbiota contains active living microorganisms. Many researches were carried out that potential probiotic bacteria such as Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus kefir, Lactobacillus kefiranofaciens, Leuconostoc mesenteroides, or yeasts like microorganisms such as Saccharomyces cerevisiae, Kluyveromyces lactis, and Kluyveromyces marxianus were isolated from kefir grains. This chapter presents the data both on the probiotic bacteria isolated from kefir grains or kefir and the probiotic properties of kefir produced with these microorganisms.

Adjunct Cultures in Cheese Technology

Cheese ripening involves highly complex biochemical events. Coagulant enzymes as well as the utilized starters play an important role in these events. Two types of starters are used: primary and secondary. The main role of the primary culture, which consists of lactic acid bacteria, is to carry out lactic production during fermentation. They contribute to proteolysis and limited flavor formation with the enzymes they possess. Secondary or adjunct cultures are used to develop the texture and to accelerate the ripening. During the selection of this type of culture, enzyme profiles (i.e., proteolytic and lipolytic activities and their autolyse levels) in cheese are the primary factors to be taken into consideration. Apart from these, the other factors are their positive effects on health, availability, and economy. Adjunct cultures include yeast, molds, and bacteria. Some of the heterofermentative lactobacilli species, in particular weakened strains, are used as adjunct cultures in order to accelerate the ripening and shorten the ripening time in fat-reduced and low-fat cheeses. This chapter explores adjunct cultures in cheese technology.

Microbial Production of Recombinant Rennet

Rennet, traditionally obtained from calves, is non-vegeterian and unethical due to the slaughter of unweaned animals. Chymosin is highly specific to the Phe105-Met106 bond of κ-casein and has low proteolytic activity. Microbial aspartic proteases can partly replace chymosin. However, recombinant DNA technology has allowed chymosin itself to be produced by bacteria, yeast, and molds. Not only rennet from calf, but from animals like goat kid, lamb, buffalo, camel, and others can be used in cheesemaking. Chymosins of these animals can be cloned and successfully expressed in microorganisms and can be employed in the production of novel as well as traditional cheese products from the milk of camel, goat, and even horse and donkey. This chapter outlines the recombinant DNA techniques applied over the past few years to improve the microbial production of recombinant rennet, from animals and plants.

Probiotic Microorganisms and Encapsulation Method Approaches

Nowadays, interest in probiotics, which are useful and necessary for healthy life, is rapidly increasing, and studies on the beneficial effects of probiotics on human health continue intensely. Every year, increasing efforts to prevent cancer, which has been anticipated, has increased the interest in probiotics and therefore synbiotics. Encapsulation methods are one of the most important protection methods currently used to ensure the viability of probiotics and their effectiveness. Especially milk and dairy products are used for many purposes such as increasing the shelf life, increasing the nutritional value, providing digestibility, shortening the ripening period, improving taste and aroma substances. The use of the microencapsulation technique alone can improve probiotic vitality. Combining microencapsulation with various food processing technologies is thought to help improve the vitality of probiotics in production and storage. In this chapter, probiotic microorganisms and encapsulation applications are explored.

The Effects of Probiotic Cultures on Quality Characteristics of Ice Cream

The manufacturing design and probiotic strain that are used in ice cream production affect sensorial, nutritional, and physicochemical properties of ice cream. Therefore, it is possible to produce better quality products or to develop existing methods by considering the effects of probiotic cultures on these properties of ice cream. The International Dairy Federation has recommended that probiotic products contain at least 107 CFU/g of viable probiotic strain before consumption, so that the therapeutic value of a probiotic product can be associated with the viability of these bacteria. The nutritional value of probiotic ice cream is related not only to the dietary components it contains, but also to the maintaining of the viability and the activity of the probiotic bacteria. This chapter provides information on the viability of probiotic strains during ice cream processing and storage. Furthermore, the effects of probiotic cultures on sensory and physicochemical properties of ice cream are also discussed.

Filamentous Fungi in Cheese Production

Filamentous fungi play important roles in the production of a variety of cheeses. The most famous are the blue cheeses, such as Roquefort or Gorgonzola, in which Penicillium roqueforti is the principal mold, and the moldy soft cheeses, such as Camembert or Brie, in which production involves Penicillium camemberti. There are also other filamentous fungi associated with certain types of cheeses, such as Mucor spp., Trichothecium roseum, and Fusarium domesticum in Saint Nectaire, Sporendonema casei in Cantal, Salers and Rodez cheeses, Scopulariopsis species in various French and Austrian cheeses, and Mucor mucedo and Mucor racemosus in the traditional Norwegian cheese Gamalost. These fungi are either inoculated on the cheese as a starter culture or stand out in mixed cultures during spontaneous fermentation. This chapter reviews the filamentous fungi used to produce different kinds of cheeses in terms of taxonomy, physiology, ecology, and mycotoxins, and the microbiological or biochemical effects of these fungi on cheese production.

Microbial Non-Coagulant Enzymes Used in Cheese Making

In this chapter, the use of microbial non-coagulant proteases, microbial lipases, and microbial transglutaminase in the cheese making procedure is discussed. Microbial proteases and lipases have been used for over 30 years to accelerate cheese ripening and consequently to enhance the cheese flavor development by increasing proteolysis and lipolysis level in a shorter time. They are commercially produced by bacteria and fungi species. Transglutaminase is a relative new enzyme, which catalyzes the cross-linking of peptide bonds and helps to improve the cheese texture and to increase the cheese yield. Today, cheeses from almost all cheese categories are produced using these enzymes.