Yoghurts

The production of yoghurt is presented schematically in Fig. 10.21. Yoghurt cultures consist of thermophilic lactic acid bacteria that live together symbiotically (Streptococcus thermophilus and Lactobacillus bulgaricus). Incubation is conducted on addition of 1.5-3% of the operating culture at 42-45 °C for about 3 h. The final product has a pH value of about 4-4.2 and contains 0.7-1.1% of lactic acid. Functional foods include yoghurts which have been incubated with probiotics. Probiotics are defined, cultured strains of lactic acid bacteria, which have been isolated from human intestinal flora, e. g., certain lactobacilli and bifidobacteria. On consumption, they are supposed to reach the large intestine and contribute to the formation of an optimal intestinal flora. 

The variety of products is increased by the addition of fruits and fruit pastes to yoghurt. 

The addition of fruit or fruit pastes and sugar yields special products (fruit yoghurts). 

An essential part of the specific yoghurt aroma comes from carbonyl compounds, predominantly acetaldehyde and diacetyl. In addition to 1-octen- 

l-nonen-3-one has also been detected as an important odorant, which has an exceptionally low odor threshold (cf. 3.7.2.1.9). An autoxida-tion product of linoleic acid, (E)-2-nonenal (Formula 10.13), is thought to be the precursor. 

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DETERMINATION OF NUTRITIONAL PARAMETERS OF YOGHURT SAMPLES THROUGH PARTIAL-LEAST-SQUARES ATTENUATED TOTAL REFLECTANCE FOURIER TRANSFORM INFRARED SPECTROMETRY... 

The aim of this work is the determination of several nutritional parameters, such as Energetic Value, Protein, Fat, and Carbohydrates content, in commercially available yoghurt samples by using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FT-IR) spectrometry and a partial least square approach. 

One of the most cotrunon processing methods for plastics is injection moulding. Nowadays every home, every vehicle, every office, every factory contains a multitude of different types of articles which have been injection moulded. These include such things as electric drill casings, yoghurt cartons, television... 

Figure 3.7 shows some early examples of this type of analysis (39), illustrating the GC determination of the stereoisomeric composition of lactones in (a) a fruit drink (where the ratio is racemic, and the lactone is added artificially) and (b) a yoghurt, where the non-racemic ratio indicates no adulteration. Technically, this separation was enabled on a short 10 m slightly polar primary column coupled to a chiral selective cyclodextrin secondary column. Both columns were independently temperature controlled and the transfer cut performed by using a Deans switch, with a backflush of the primary column following the heart-cut. 

Figure 3.7 [continued) (b) Chromatograms of (iii) the dichloromethane extract of strawberry fruit yoghurt analysed with an apolar primary column, with the heart-cut regions indicated, and (iv) a non-racemic mixture of y-deca-(Cio) and 7-dodeca-Cj2 lactones isolated by heart-cut transfer, and separated by using a chiral selective modified cyclodextrin column. Reproduced from A. Mosandl, et al J. High Resol. Chromatogr. 1989, 12, 532 (39f. 

Milk is converted in the creamery and associated factories to whole or market milk, skimmed milk, creams, hutters, cheeses, dried milk, whey, yoghurts, hutter oil, condensed milk, milk powder and ice cream [46]. 

Chill temperature stores for milk, hutter, cheese, yoghurt and other liquid milk products Frozen storage for hutter (and sometimes cheese)... 

Microorganisms have been identified and exploited for more than a century. The Babylonians and Sumerians used yeast to prepare alcohol. There is a great history beyond fermentation processes, which explains the applications of microbial processes that resulted in the production of food and beverages. In the mid-nineteenth century, Louis Pasteur understood the role of microorganisms in fermented food, wine, alcohols, beverages, cheese, milk, yoghurt and other dairy products, fuels, and fine chemical industries. He identified many microbial processes and discovered the first principal role of fermentation, which was that microbes required substrate to produce primary and secondary metabolites, and end products. 

Yeast and culture starter Lactobacillus bulgaricus Lactic acid bacteria Cheese and yoghurt production... 

Food Diary products (cheese, yoghurts, etc.) Non-sterile... 

Poly(styrene) Yoghurt pots, plastic cutlery. foamed meat/fish... 

Fruit preprations for yoghurt are a typical example, how the influence of pectins in these preparations can be characterized with the help of rheological methods (Kratz and Dengler, 1995), using... 

The loss of viscosity should be large enough to render a product, that can be easily pumped with no negative effect for the pieces of fruit, and can be easily mixed with the yoghurt, but afterwards will regenerate enough to produce a pleasant creamy texture in the final product. 

The very special demands on the pectins used in yoghurt fruit preparations show the usefulness of rheological measurements. Figure 4 and 5 explain the difference in rheological behaviour of fruit preparations made from... 

Recently, organic farms have been encouraged to make added value products such as cheese and yoghurt. The farmer processes the milk and can fix a price for the farmhouse-produced cheese or yoghurt. It needs to be a unique quality product, or have a superior image, if it is going to sell well at a higher price than a similar product in the local supermarket. 

In two years, organic yoghurt sales rose from 17.2 million to 39.1... 

Siitonen S, Vapatalo H, Salminen S, Gordin A, Saxelin M, Wikbeig R, Kirkkola AL Effect of Lactobacillus GG yoghurt in prevention of antibiotic assoicated diarrhoea. Ann Med 1990 22 57-59. 

Brimar, H. 2002. In A Study of Differently Processed Fruit-Preparations Used for Manufacturing Strawberry Yoghurt . Master of Science Thesis, Lund University, Sweden and I.V.T.P.A., Milano, Italy. 

Enzymatic assay techniques have been developed for several additives by Merck. BIOQUANT kits are available for aspartame (intense sweetener) and nitrate (preservative). Gromes et al. (1995) applied the Bioquant kit to determination of aspartame in yoghurt, quark and confectionery. For low concentrations of aspartame a blank correction procedure was necessary. Recoveries of aspartame were in the range 93-102%. 

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