Search

Several encapsulation variants to deliver the anthocyanins from cornelian cherry fruits, using soy proteins alone or in combination with maltodextrin and freeze-drying or spray-drying, were studied. The resulting powders were characterized in terms of flow properties, encapsulation retention and efficiency, color, bioavailability of anthocyanins with simulated gastrointestinal conditions, particles microstructure, and stability during storage. The highest encapsulation efficiency was obtained when using soy proteins-maltodextrin biopolymeric systems with spray-drying. The in vitro studies showed that the best protection was delivered when using a mixture of coating materials, allowing a controlled release of the anthocyanins in the intestinal environment. The powder obtained by spray-drying had nearly perfect spherosomes, in which the anthocyanins were retained as droplets coated by fine membranes. Anthocyanins are best protected during storage at 8 °C and low aw values. This study showed that the microencapsulation of cornelian cherry anthocyanins using spray-drying is more effective than freeze-drying and can be used to develop new functional foods and supplements.

Capability of thyme natural antimicrobials (NAs) to reduce the intensity of high pressure processing (HPP) and enhance the inactivation of Listeria monocytogenes in fresh cheese was investigated. Thyme extracts were obtained by supercritical fluid extraction at 30 MPa and 40 MPa and their concentration was estimated in units of carvacrol (190.44–609.57 μg/mL). The acceptable sensorial threshold of thyme extract in cheese was 0.2% (v/w), a value lower than the MIC for L. monocytogenes. Detailed kinetic studies of L. monocytogenes inactivation in cheese were performed following HPP (200–300 MPa) treatments. A maximum 1.68-log10 CFU/g supplementary reduction was achieved for L. monocytogenes in cheese with HPP & NAs than without NAs. The kinetic parameter zp indicated an accelerated inactivation of L. monocytogenes when HPP was combined with thyme NAs, as hurdle applied to fresh cheese (55.99 MPa for HPP and 33.29 MPa for HPP with thyme NAs). Industrial relevance Applied as a post-processing treatment high pressure processing (HPP) is considered an effective listericidal tool that produces limited quality changes in foods compared to other preservative methods. In order to overcome the main drawback related to HPP effect on cheese structure, a combination of pressure with natural antimicrobials (NAs) is proposed for reducing the intensity of processing while improving microbiological safety of food. The efficacy of L. monocytogenes inactivation in cheese by HPP and HPP with NAs from thyme was kinetically evaluated and modeled in the present work. The current results provide support for the industrial development of more effective combined HPP with NAs treatment, able to minimize the risk of Listeria presence in cheese.

Bambara bean protein is a promising ingredient for further applications in food and non-food industries. In this study, structural changes in Bambara bean protein isolate (BBPI) produced during high pressure processing (HPP) in the 200–600 MPa range at different pH (4.5, 7 and 9) were investigated by fluorescence spectroscopy and molecular modelling. SDS-PAGE analysis indicated that vicilin, a 7S globulin, was the major protein in BBPI. Intrinsic fluorescence analysis at pH 4.5 showed a red-shift when BBPI was treated at high pressure. Phase diagram and quenching experiments demonstrated a third-state model for dissociation of vicilin at pH 9, and existence of four intermediate states when HPP was applied on BBPI at pH 7. Detailed information at atomic level on the structural changes of main proteins from BBPI was provided by molecular modelling. At a glance, HPP resulted in decrease of the total number of hydrogen bonds stabilizing the structure of proteins, which altered exposure of both Tyr and Trp residues. This work is important in development of new food formulations with adequate nutritional and functional properties based on Bambara bean protein.

The aim of this research was to analyze and model the combined effect of pressure and temperature upon Aspergillus ochraceus spores exposed to high pressure carbon dioxide (HPCD) treatment and to estimate the kinetic parameters. Lately, many empirical or semi-empirical mathematical models were presented and discussed for different microorganisms, mainly bacteria, demonstrating an increased need for tools able to quantify the parameters of the microbial inactivation. A. ocharaceus HPCD inactivation was adequately described by first order reaction kinetics and a synergic effect of pressure and temperature was noticed for the experimental range where pressure varied from 5.4 to 7.0 MPa and temperature varied from 30 to 50 °C. The decimal reduction time ( D ) ranged from 47.07 min at 5.4 MPa and 30 °C to 5.04 min at 7.0 MPa and 50 °C. In this study three mathematical models were evaluated in order to find the best one that describes accurately the influence of pressure and temperature on the studied microbial response. An empirical exponential equation, that described pressure and temperature influence in the form of a polynomial equation, was found to best describe the dependence of A. ochraceus HPCD inactivation in the range 5.4–7.0 MPa and 30–50 °C. This work adds insight to moulds inactivation at the already existing body of knowledge on bacteria inactivation with HPCD and provides support to potential industrial applications of the minimal–thermal methods that combine high pressure and mild temperature with carbon dioxide for different food matrixes.