Impact of High-Pressure Process on Probiotics: Viability Kinetics and Evaluation of the Quality Characteristics of Probiotic Yoghurt.

The impact of high-pressure (HP) processing on the viability of two probiotic microorganisms (Bifidobacterium bifidum and Lactobacillus casei) at varying pressure (100-400 MPa), temperature (20-40 °C) and pH (6.5 vs. 4.8) conditions was investigated. Appropriate mathematical models were developed to describe the kinetics of the probiotics viability loss under the implemented HP conditions, aiming to the development of a predictive tool used in the design of HP-processed yoghurt-like dairy products. The validation of these models was conducted in plain and sweet cherry-flavored probiotic dairy beverage products pressurized at 100-400MPa at ambient temperature for 10 min. The microbiological, rheological, physicochemical and sensory characteristics of the HP-treated probiotic dairy beverages were determined in two-week time intervals and for an overall 28 days of storage. Results showed that the application of HP in the range of 200-300 MPa had minimal impact on the probiotic strains viability throughout the entire storage period. In addition, the aforementioned HP processing conditions enhanced the rheological and sensory properties without affecting post-acidification compared to the untreated product analogues.

Multiscale design of a dairy beverage model composed of Candida utilis single cell protein supplemented with oleic acid.

One of the main challenges in the food industry is to design strategies for the successful incorporation of natural sources of bioactive compounds. Recently, yogurts and other fermented dairy beverages have been proposed as ideal carriers of such bioactive compounds such as fatty acids and antioxidants that could improve consumers' health. However, the incorporation of new ingredients causes functional and structural modifications that may affect the consumers' preferences. In this work, a dairy beverage model supplemented with oleic acid has been designed by partial substitution of milk by Candida utilis single-cell protein extract. The changes in the structural properties of this new beverage were evaluated by following the fermentation process, pH, aggregate size, microstructure, and changes in rheological properties. Furthermore, molecular dynamics simulations were carried out to analyze the interaction between its main components. Our data revealed that samples with a percentage of milk substitution of 30% showed a higher viscosity as compared with the other percentages and less viscosity than the control (no substitution). These samples were then selected for fortification by incorporating oleic acid microcapsules. A concentration of 1.5 g/100 g was shown to be the optimal quantity of microcapsules for oleic acid supplementation. Molecular dynamic simulations revealed glutathione as an important component of the micro-gel structure. The present study forms the basis for novel studies where Candida utilis single-cell protein and microencapsulated essential oils could be used to design innovative bioproducts.

Avaliação microbiológica de bebidas lácteas fermentadas adquiridas no comércio varejista do sul de Minas Gerais / Microbiological evaluation of fermented dairy beverages acquired in the retail marked of the southern region of Minas Gerais State

O objetivo deste trabalho foi avaliar as características microbiológicas das bebidas lácteas fermentadas comercializadas no sul de Minas Gerais. Realizou-se a enumeração coliformes totais e termotolerantes, fungos filamentosos e leveduras e bactérias lácticas. Foram coletadas amostras de cinco marcas de bebidas lácteas comercializadas em Lavras, com quatro repetições, de diferentes lotes de fabricação, para serem submetidas às análises microbiológicas. As bebidas lácteas fermentadas apresentaram-se dentro dos padrões estipulados pela ANVISA quanto à presença de contaminação microbiana, pois os mesmos não foram detectados nas amostras analisadas. A contagem de bactérias láticas foi menor que 10(6) UFC/mL em todas as análises, apresentando-se fora dos padrões estabelecidos pela legislação brasileira para as bebidas lácteas fermentadas.

The objective of this work was to evaluate the microbiological characteristics of fermented dairy beverages commercialized in southern Minas Gerais. The enumeration of total and heat-tolerant coliforms, filamentous fungi and lactic bacteria and yeasts was carried out. Samples were collected from different manufacturing lots of five brands of dairy beverages commercialized in Lavras-MG, with four repetitions and submitted to microbiological analyses. The fermented dairy beverages met the standards required by ANVISA for presence of microbial contamination, since no contamination was detected in the samples analyzed. Lactic bacteria count was lower than 10(6) UFC/mL in all the analyses and did not meet out legal parameters established by the Brazilian legislation for fermented dairy beverages.