Fast detection and identification of microorganisms is a challenging and significant feature from industry to medicine. Standard approaches are known to be very time-consuming and labor-intensive (e.g., culture media and biochemical tests). Conversely, screening techniques demand a quick and low-cost grouping of bacterial/fungal isolates and current analysis call for broad reports of microorganisms, involving the application of molecular techniques (e.g., 16S ribosomal RNA gene sequencing based on polymerase chain reaction). The goal of this review is to present the past and the present methods of detection and identification of microorganisms, and to discuss their advantages and their limitations.
Fruit juices represent a promising carrier for probiotic bacteria; however, there are some drawbacks and limits that could preclude their production at the industrial level, namely the survival of probiotics throughout storage, and the possible impact of bacteria on the sensory traits and overall acceptance. This review addresses the inoculation of probiotics in juices; with a special focus on the possibilities and challenges for future; i.e., why probiotics in juices and which kind of microorganisms; some drawbacks and how to improve the viability of probiotics; and some ideas on the sensory impact.
Canestrato Pugliese cheeses from ewe milk were produced according to a traditional protocol and by adding 7.0 log10 cfu of fresh cells per gram of Bifidobacterium bifidum Bb02, Bifidobacterium longum Bb46, or both species. The traditional technology was modified slightly to favor the survival of probiotic microorganisms. After 56 d of ripening, the survival of B. bifidum Bb02 and B. longum Bb46 was 6.0 and 5.0 log10 cfu/g, respectively. After 19 d cheeses contained ca. 7.0 log10 cfu/g of bifidobacteria. Compared to traditional cheese, the addition of bifidobacteria seemed to support the growth and survival of mesophilic lactobacilli and Streptococcus thermophilus, used as starter, during ripening. No significant differences were observed in the main chemical composition, and only a slightly higher concentration of acetic acid was found in cheeses with bifidobacteria added. On the contrary, alpha- and beta-galactosidase activities were markedly more pronounced in the presence of bifidobacteria, especially with B. bifidum Bb02. In contrast with traditional cheese, the lactose was completely hydrolyzed in cheeses made with bifidobacteria. Urea-PAGE electrophoresis of the pH 4.6-soluble and pH 4.6-insoluble N fractions did not show appreciable variations. Only the reversed-phase-HPLC analysis of the pH 4.6-soluble N showed a slightly more complex profile in the presence of bifidobacteria. This finding was in agreement with the higher value of the pH 4.6-soluble N/total N ratio and with the more pronounced amino-, imino-, and dipeptidase activities found in all the cheeses with the bifidobacteria added, especially B. bifidum Bb02. No differences were found in the free amino acid and free fatty acid contents. The amino acids glutamic acid, valine, proline, leucine, and lysine and the fatty acids butyric, caproic, capric, and oleic acids were found at the highest concentrations. The sensory evaluation did not show significant differences, and Canestrato Pugliese cheeses were characterized by small and uniformly distributed eyes, were pale yellow, had an elastic consistency and a Pecorino-like smell, were very salty, and tended to be moderately piquant.
In recent years, there has been a growing interest in the design of novel nonthermal processing systems that minimally modify sensory, nutritional, and functional properties of fruit and vegetable juices and beverages. The benefits of nonthermal treatments are strongly dependent on the food matrix. Thus, an understanding of the effects that these technologies exert on the properties of juices and beverages is important to design and optimize technological parameters to produce value‐added products. This review covers research on nonthermal electrical treatments, high pressure processing, ultrasound, radiation processing, inert gas treatments, cold plasma, and membrane processing. Advances towards optimization of processing conditions, and combined technologies approaches have been also extensively reviewed. This information could be useful to: (1) manage processing systems and optimize resources; (2) preserve nutritional value and organoleptic properties, and (3) provide processing conditions for validation of these technologies at the industrial scale.
Fruit and vegetable juices and beverages are generally preserved by thermal processing, currently being the most cost-effective means ensuring microbial safety and enzyme deactivation. However, thermal treatments may induce several chemical and physical changes that impair the organoleptic properties and may reduce the content or bioavailability of some nutrients; in most cases, these effects are strongly dependent on the food matrix. Moreover, the efficacy of treatments can also be affected by the complexity of the product and microorganisms. This review covers researches on this topic, with a particular emphasis on products derived from different botanical sources. Technologies presented include conventional and alternative thermal treatments. Advances toward hurdle-based technology approaches have been also reviewed.
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