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When you are hunting for a healthy snack, yogurt may be one that comes to mind. Rich in protein and calcium, Greek yogurt in particular has many health benefits, and is packed with gut-loving microbes such as probiotic bacteria that remain in the yogurt after fermentation. Choosing a flavored yogurt instead may seem like a small upgrade, but the difference in nutrition can be quite substantial. In many cases the major negative impact is from sugar. While natural yogurt does contain lactose, the natural sugar found in milk (Greek yogurt contains about 50% less since much of it is drained off) many flavored yogurts also contain added sugar to make them taste more appealing……….Continue reading….
By Elaine Todd
Source: Sciencing
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Critics:
As it may contain live cultures, yogurt is often associated with probiotics, which have been postulated as having positive effects on immune, cardiovascular or metabolic health. A 2011 review stated that high-quality clinical evidence was insufficient to conclude that consuming yogurt lowers the risk of diseases or otherwise improves health.
Meta-analyses found that consuming 80 grams per day of low-fat yogurt was associated with a lower risk of developing type 2 diabetes and a lower incidence of hip fracture in post-menopausal women. A 2021 review found a cause-and-effect relationship between yogurt consumption and improved lactose tolerance and digestion, and that potential associations exist between yogurt consumption and improving bone health, as well as lowering the risk of some diseases, including cancers and metabolic syndrome.
Daily intake of 50 grams of yogurt has been shown to reduce risk of overweight or obesity by 13%, and reduce risk of type 2 diabetes by 7%. Yogurt consumption has been associated with reduced risk of cardiovascular disease, and insulin resistance. Some of the benefits were somewhat better for the lower fat yogurts. Many commercial yogurt products are supplemented with extra probiotic bacteria.
Yogurt made with raw milk can be contaminated with bacteria that can cause significant illness and even result in death, including Listeria, Cryptosporidium, Campylobacter, Brucella, Escherichia coli and Salmonella. Yogurts can also be contaminated with aflatoxin-producing Aspergillus flavus, Aspergillus parasiticus and Aspergillus nomius.
Contamination occurs in traditionally prepared yogurts more often than industrially processed ones, but may affect the latter as well if manufacturing and packaging practices are suboptimal. When mold forms on yogurt, scraping it off does not eliminate it, as yogurt’s consistency allows the mold to penetrate and spread deeply under the surface.
Yogurt is made by warming milk to a temperature (30–45 °C (86–113 °F)) that will not kill the live microorganisms that turn the milk into yogurt, inoculating certain bacteria (starter culture), usually Streptococcus thermophilus and Lactobacillus bulgaricus, into the milk, and then keeping it warm for several hours (4–12 hours).
Milk with added dried milk produces a firmer yogurt. Yogurt production provides two significant barriers to pathogen growth, heat and acidity (low pH). Both are necessary to ensure a safe product. Acidity alone is insufficient, as shown by recent outbreaks of food poisoning by E. coli O157:H7 that is acid-tolerant. E. coli O157:H7 is easily destroyed by pasteurization (heating); the initial heating of the milk kills pathogens as well as denaturing proteins.
The microorganisms that turn milk into yogurt can tolerate higher temperatures than most pathogens, so that a suitable temperature not only encourages the formation of yogurt, but inhibits pathogenic microorganisms. Once the yogurt has formed it can, if desired, be strained to reduce the whey content and thicken it.
Yogurt is a viscous, shear-thinning, non-Newtonian fluid that forms when milk, a Newtonian fluid, is fermented, causing protein aggregation and subsequent gelation. The result is a soft solid that can be modeled via the interactions of the casein proteins. The microstructure of yogurt is affected by its fat and protein content and its processing conditions.
In low-fat formulations, the microstructure is a network of casein protein globules joined via clusters and strands that encapsulate pores: these pores house the aqueous phase and the bacterial cultures of the yogurt. Stirred yogurt formulations have a coarser distribution of loosely associated casein particulates due to the shear forces and resulting particle-particle collisions induced during the mixing process. After stirring, yogurt is more accurately defined as a weak gel.
The mechanical properties of yogurt are typically assessed using rheometry, which quantifies the deformation and flow response of soft materials subject to shear forces. As is central in materials science, the rheological properties of yogurt are dictated by a variety of processing factors, including the ratios of dry and wet matter, thermal treatments, milk origin, starter cultures, and yogurt type.
Although cow milk is a common choice for yogurt production, other milks, such as goat, sheep, and camel, produce different rheologies. Goat milk yogurt has a low viscosity and a thinner texture when compared to cow milk yogurt. Conversely, sheep milk, having higher content of solids, has a higher viscosity and thicker texture when compared to cow milk yogurt.
Yogurt can further be characterized as “set” versus stirred, wherein set yogurts are processed and sold in the same container, and stirred yogurts are mixed prior to packaging in a secondary container.
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