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Should yoghurt cultures be considered probiotic?

Digestive System Research Unit, University Hospital Vall d'Hebron, Barcelona, Spain.
British Journal Of Nutrition (Impact Factor: 3.34). 07/2005; 93(6):783-6. DOI: 10.1079/BJN20051428
Source: PubMed

ABSTRACT Probiotics are live micro-organisms that when administered in adequate amounts confer a health benefit on the host. Consumption of yoghurt has been shown to induce measurable health benefits linked to the presence of live bacteria. A number of human studies have clearly demonstrated that yoghurt containing viable bacteria (Streptococcus thermophilus and Lactobacillus delbrueckii sp. bulgaricus) improves lactose digestion and eliminates symptoms of lactose intolerance. Thus, these cultures clearly fulfil the current concept of probiotics.

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    ABSTRACT: Yoghurt is a versatile food as it is an important source of calcium, phosphorus, magnesium, potassium, riboflavin, vitamin A and protein. As a fermented milk product, it is a natural source of probiotics, which helps to maintain a healthy gut and immune system. The popularity of yoghurt has increased due to its perceived health benefits resulting in significant increase in consumption. Many types of stirred yoghurt are available in the market, varying in fat, sugar, texture, flavor and type of fruits. It has keeping quality of 1-2 days at ambient temperature, and 1 week under refrigerated condition. Microbes in yoghurt may be derived from a variety of sources. The presence of microbes in daily products including yoghurt are undesirable, at these render the milk products of inferior quality. Yeasts and moulds are mainly responsible for the spoilage of yoghurt, as they are not affected by low pH. Microbiological specifications should be applied to some additive employed in the manufacture of yoghurt. Recently, the BioLumix test method has been developed for rapid detection of coliforms, yeasts and moulds. It is emphasized that the activity of starter culture used for the production of yoghurt should be critically monitored periodically to get a product of good quality. Education of food handlers about the importance of high standards of personal hygiene is very essential for hygienic production of milk products in dairy industries. In addition, the application of GHP and HACCP during the production of yoghurt is highly imperative from food safety point of view. INTRODUCTION Milk is used globally in the manufacturing of different types of dairy products. In India, people are very fond of milk made preparations, and hence, a large variety of milk products are available in the market (Pal and Jadhav,2013a). The cheese, butter, yoghurt, and milk power have captured global market. Yoghurt is one of the oldest produced foods in human history. It is a unique food, which is consumed worldwide, without the restriction of any taboo, tradition or religion. Cow milk is most commonly used worldwide to prepare yoghurt. However, the milk from goats, camel, water buffaloes, and yaks are also employed to make yoghurt. The name yoghurt is derived from the Turkish word 'Jugurt' reserved for any fermented food with acidic taste (Younus et al., 2002). In 1907, Dr.Metchnikoff co-workers isolated and named one of the yoghurt bacteria, Lactobacillus bulgaris (Jay,2000). The popularity of yoghurt soared in the 1950 and 1960 with the boom of health food culture. Presently, fermented foods constitute about 25% of the foods consumed worldwide. Usually, these foods are considered safe against food borne infections (Adebayo et al.,2014). The changes in the physical, chemical and microbiological structures of yoghurt determine the storage and shelf life of the product (Sofu and Ekinci, 2007). Fungi, especially the yeasts are a major cause of spoilage of yoghurt as low pH provides a selective environment for their growth. The use of poor quality of milk, unsuitable starter culture, improperly cleaned utensils, and unfavourable temperature of incubation, are responsible to lower the quality of yoghurt (De,1980).Yoghurt should not be freezed, as it affects the texture and quality. Further, it should be protected from other foods with strong odour by sealing it tightly. Yoghurt should be kept in refrigerator after it is purchased. Clean spoon should be used to take yoghurt into the bowel. In order to avoid contamination, it is imperative not to return unused portion of yoghurt to the original container. Yoghurt produced under good manufacturing practice (GMP) should not contain > than 10 yeast cells, and should have a shelf life of 3-4 weeks at 5 0 c. Yoghurt having initial yeast counts of >100 CFU/g tend to spoil quickly (El-Bakri et al.,2009). Hygienic practices in the production can improve the microbial quality standards of yoghurt. Strict supervision and stringent quality control standards are imperative to improve the microbial safety of the product, and ultimately reduce the microbial hazards. This communication describes the hygienic and microbiologic quality of yoghurt. Manufacture of Yoghurt Yoghurt is a dairy product prepared by bacterial fermentation of milk. The equal amount of two pure culture of bacteria, namely Streptococcus thermophilus and Lactobacillus bulgaris is added to whole or defatted homogenized milk to make yoghurt (Mahindru,2009).The starter cultures determine the body, texture and flavor of the final yoghurt (Chandan and Kilara,2013).They preserve the food by
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    ABSTRACT: Streptococcus thermophilus can grow in the presence of oxygen and survive at low concentrations of H2O2. Glutathione (GSH) plays an important role in living cells, but its protective roles against oxidative stress in S. thermophilus remain unclear. We assessed intracellular GSH accumulation under both anaerobic and aerobic growth conditions in 40 S. thermophilus strains. The GSH level in different strains was found to be strain-specific. A gshF gene, encoding the GSH synthesis, was inactivated in the genome of strain SDMCC18. The growth and survival of the resulting mutant SDMCC18ΔgshF were significantly reduced after exposure to oxygen and H2O2. However, the oxidative tolerance of the mutant strain was restored by exogenous GSH. Our findings provide a new strategy to improve the robustness of S. thermophilus in starter manufacture and industrial applications. We, for the first time, demonstrated the GSH synthesis and its transport from the culture medium in S. thermophilus.
    International Dairy Journal 02/2015; 45. DOI:10.1016/j.idairyj.2015.01.015 · 2.30 Impact Factor
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    ABSTRACT: Cassava retting is one of the main step for cassava processing. This step involve some microorganisms which activity impact on the quality of cassava derived products. With the aims of ensuring a good quality of cassava products, tree strains of microorganism namely Lactobacillus sp., Saccharomyces sp., and Rhyzopus sp., were tested as starter culture on cassava variety TMS 3001, fermentation. The use of this starter made of 10 9 cells/ml of Lactobacillus sp., 10 6 cells/ml of yeast, and 10 4 cells/ml of mould spores, permitted to reduce the retting time from five days to two days, to reduce cassava cyanogen by 95% and to ameliorate the hygienic quality of by products by eliminating pathogens development. This new approach may encourage industrial production of stabilized quality cassava derived product. RÉSUMÉ: Le rouissage du manioc est l'une des principales étapes des procédées de transformation du manioc. Celle-ci fait intervenir une succession de divers micro-organismes dont l'activité a un impact sur la qualité des produits finis. Afin de permettre un meilleur contrôle du rouissage naturel, et d'assurer une meilleure qualité des produits de transformation du manioc, trois souches microbiennes dont Lactobacillus sp., Saccharomyces sp., et Rhyzopus sp., ont été testées comme starter sur du manioc amers de variété TMS 3001. L'utilisation de ce starter composé de 10 9 cellules/ml de Lactobacillus sp., 10 6 cellules/ml de levures, et 10 4 cellules/ml de spores fongique, a permis de réduire la durée du rouissage de cinq jours à 40 heures, de réduire le taux de glucosides cyanogénétiques de 95%, et d'améliorer la qualité microbiologique du manioc rouis en éliminant le développement des germes pathogènes. Cette nouvelle approche permet d'augurer une production à l'échelle industrielle des produits fermentés dérivés du manioc de qualité standardisé.

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