Physico-chemical and microstructural properties of food dispersions

The macroscopic properties of oily food dispersions, such as rheology, mechanical strength, sensory attributes (e.g. mouth feel, texture and even flavour release) and as well as engineering properties are strongly determined by their microstructure, that is considered a key parameter in the understanding of the foods behaviour . In particular the rheological properties of these matrices are largely influenced by their processing techniques, particle size distribution and composition of ingredients. During chocolate manufacturing, mixtures of sugar, cocoa and fat are heated, cooled, pressurized and refined. These steps not only affect particle size reduction, but also break agglomerates and distribute lipid and lecithin-coated particles through the continuous phase, this considerably modify the microstructure of final chocolate. The interactions between the suspended particles and the continuous phase provide information about the existing network and consequently can be associated to the properties and characteristics of the final dispersions. Moreover since the macroscopic properties of food materials, are strongly determined by their microstructure, the evaluation and study of the microstructural characteristics, can be very important for a through understanding of the food matrices characteristics and to get detailed information on their complexity. The aim of this study was investigate the influence of formulation and each process step on the microstructural properties of: chocolate type model systems, dark milk and white chocolate types, and cocoa creams. At the same time the relationships between microstructural changes and the resulting physico-chemical properties of: chocolate type dispersions model systems dark milk and white chocolate were investigated.Le proprietà macroscopiche di dispersioni alimentari a base oleosa tra cui quelle reologiche, meccaniche e sensoriali (consistenza, texture, palatabilità, viscosità, stabilità fisica, ecc.) sono fortemente influenzate dalla loro microstruttura che è considerata un parametro chiave nella comprensione del “comportamento macroscopico” degli alimenti. In particolar modo le proprietà reologiche di tali matrici alimentari sono direttamente influenzate sia dalla formulazione che dal processo di produzione. Durante la produzione di cioccolato e/o surrogati a base di cacao, miscele di zucchero, cacao e grassi vengono riscaldate, raffreddate, pressurizzate e raffinate (Beckett 2000). Questi operazioni tecnologiche la contribuiscono a ridurre la dimensione delle particelle, a rompere gli agglomerati e a distribuire grassi e lecitina attorno alle singole particelle, modificandone la loro microstruttura . Poiché le proprietà macroscopiche di tali matrici alimentari sono fortemente determinate dalla loro microstruttura, la valutazione delle caratteristiche microstrutturali risulta essere molto importante al fine di studiare e ottenere dettagliate informazioni sulla loro complessità. Il presente studio si è proposto pertanto di valutare, mediante tecniche dirette di microscopia ed indirette di laser light diffraction, l’influenza delle diverse formulazioni e di ogni singola fase del processo produttivo sulle proprietà microstrutturali di: sistemi modello a base oleosa, cioccolato fondente, al latte e bianco e surrogati a base di cacao. Parallelamente sono state investigate le relazioni esistenti tra le caratteristiche micro strutturali delle suddette matrici e le loro proprietà reologiche e chimico-fisiche

Development and characterization of fermented soy beverages containing encapsulated or non-encapsulated vaginal probiotics

Human microbial niches such as the healthy vagina, are recently emerging as “unconventional” sources of candidate probiotics capable of preventing from different vaginal diseases. These microorganisms could be provided as oral preparations since they can reach the vaginal niche passing through the gastrointestinal tract. However, their use in food would be challenging. The aim of this work was to develop and characterize fermented soy beverages with encapsulated and non-encapsulated vaginal lactobacilli, namely Lactobacillus crispatus BC4 and Lactobacillus gasseri BC9, as future dietary strategies for vaginal dysbiosis. The viability of vaginal strains remained stable at 7 log CFU/mL of product during the entire 28 days of storage, despite the use of encapsulated or non-encapsulated bacteria. Samples containing encapsulated bacteria, especially E-BC4+BC9, showed higher Water Holding Capacity (62.29%), lactic acid content (1.43%), and a remarkable antagonistic activity against enteropathogens. Moreover, encapsulation protected the strains from simulated GIT conditions (>1 Log) but reduced the acceptability of the final products. Overall, strain BC4 and BC9, alone or in mix, demonstrated to be promising co-starter cultures providing a characteristic flavor (pleasant smell and taste) and aroma (lower hexanal, benzaldehyde and higher diacetyl, and 2,3-pentanedione, compared to control) to the fermented soy beverages

Influence of chitosan on thermal, microstructural and rheological properties of rice and wheat flours-based batters

[EN] Wheat flour replacement by rice flour is a key strategy in gluten-free batter production. Rice flour needs hydrocolloids to offset the development of the network of the mix. In this context, the aim of this work was to analyze the influence of chitosan (0-1 g/100 g of batter) addition on the microstructural, rheological and thermal properties of wheat:rice flours batters (100:0; 70:30, 30:70 and 0:100 (g/g)). Results showed that increasing replacement of wheat flour by rice one decreased the consistency (K) and the yield stress (To), and increased the flow behavior index (n) because of the absence or lower gluten content. However, the addition of only 0.25 g/100 g chitosan to rice flour formulation (0:100 (g/g)) increased its viscosity (from 371 to 1006 mPa s), exhibiting a rheological behavior similar to wheat flour formulation (100:0 (g/g) (1050 mPa s)). Chitosan enhanced consistency and structural agglomeration, and the interaction among ingredients, especially in batters with high content of rice flour (30:70 and 0:100 (g/g)). Lastly, chitosan incorporation did not significantly modify thermal properties, excepting in rice-flour batters (0:100 (g/g)), reducing T-m, Delta H-m, and thus, increasing the bound water content (from 17 to 32 g/100 g). (C) 2017 Elsevier Ltd. All rights reserved.The authors want to acknowledge the financial support of Universitat Politecnica de Valencia for the scholarship to support Mariola Sansano Tomas' PhD studies and the mobility grant to University of Bologna (Italy).Sansano, M.; Heredia Gutiérrez, AB.; Glicerina, V.; Balestra, F.; Romani, S.; Andrés Grau, AM. (2018). Influence of chitosan on thermal, microstructural and rheological properties of rice and wheat flours-based batters. LWT - Food Science and Technology. 87:529-536. doi:10.1016/j.lwt.2017.09.036S5295368