Rediscovering acidophilus milk, its quality characteristics, manufacturing methods, flavor chemistry and nutritional value

Fermented dairy products represent an excellent source for a wide range of probiotics with several health benefits that add to the positive value of conventional milk. Acidophilus milk is a regular milk enriched with Lactobacillus acidophilus, one of the beneficial bacterial species found in the colon, that renders the product to exhibit an immunostimulant, anti-hypercholesterolemic, anti-inflammatory, or chemopreventive effect especially against colon cancer; in addition, for lactose intolerance treatment. However, most of bacterial species are very demanding and require specific nutritional and environmental conditions to survive. Probiotics suggested levels in fermented milk range from 10⁶-10⁹ colony-forming units per milliliter (CFU/mL). The supplementation or fortification of acidophilus milk with different additives can improve not only the probiotics viability, nutritional value, and sensory properties but also its health benefits; this presents a strategy to improve its overall quality that has yet to be fully exploited by the dairy industry. Nowadays, several acidophilus milk products are flavored or sweetened with no detailed report on accompanied physical or chemical changes, which would ultimately affect consumer's preference and consumption. The main goal of this review is to present an up to date overview of the different fortified acidophilus milk products in context of different probiotic species, additives, and flavor-promoting compounds generated during the fermentation process. Analysis of extrinsic factors (sensory profile) and intrinsic factors (physicochemical characteristics and flavors) can predict the consumers' impression for new products and contribute to establishing a reference standard for the dairy industry towards the development of novel functional foods. Moreover, introduction to advanced analytical technologies exemplified in metabolomics technology is presented to determine acidophilus milk metabolites profile and distinguish different potential markers to be applied in the future in industrial section to improve the safety, quality, and authenticity of other fermented dairy products.