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The aim of this study was to assess the inhibitory effect of three commercial bioprotectant agents on the growth of yogurt-spoiling fungi. Mucor circinelloides, Mucor racemosus, Penicillium spp., Saccharomyces exiguus, and Candida intermedia, commonly involved in the spoilage of dairy products, were isolated from spoiled yogurt and were fully characterized using molecular and phenotypic methods. HOLDBAC-YMC™, Lyofast-FPR2™ and MicroGARD 200™ were used as antifungal products. An optimized experimental mixture design was applied to determine the proportion of each bioprotectant in terms of growth-inhibition response against the fungal strains in standard laboratory media. The results of the challenge tests showed that the application of bioprotectants inhibited the growth of the moulds in the range of 85–100% and the growth of yeast between 1.23 and 5.40 log cycles. The optimal combination of the bioprotectants was determined, tested in standard laboratory media and found to inhibit fungal growth. The antifungal effect of the optimal combination of the bioprotectants was validated in yogurt against the most resistant fungal species of the study, M. circinelloides and C. intermedia. The bioprotectants elicited antifungal effect in yogurt by completely inhibiting all of the tested fungi compared to controls. To the best of our knowledge, this is the first time a mixture of commercial bioprotectants has been tested on yogurt as a potential alternative for the biopreservation of yogurt in order to reduce spoilage of fermented dairy products and economic losses.

BACKGROUND The search for natural, novel, high-quality, stable food ingredients is an ongoing practice in the food industry. Pulp of borojo (Borojoa patinoi Cuatrecasas), which is a fruit of the Colombian Pacific region, can be separated into three phases: liquid (LP), medium (MP) and solid (SP) phases. The objective of this work was to evaluate the effect of the three-phase composition and gum arabic on their glass transitions temperatures (Tg). The best mixture, LP-MP, MP-SP and LP-SP and gum arabic (GA) was identified by response surface methodology. RESULTS When adding GA to SP borojo phase in a 1:1 proportion, the resulting Tg of the mixture was 132.27 °C whereas Tg for GA and SP-phase were 154.89 °C and 79.86 °C respectively, which supported this combination as attractive from a processing perspective and supports an industrial advantage of using borojo as food ingredient. Phases were characterized by high-performance liquid chromatography, Fourier transform infrared spectroscopy, confocal laser scanning microscopy and mass spectrometry. Low molecular weight compounds such as fructose for MP lowered Tg whereas the presence of lignin increased Tg of the mixtures as with the SP. CONCLUSIONS The addition of GA significantly increased Tg of borojo phases so leading to propose them as novel food processing materials. © 2015 Society of Chemical Industry

Sorption mechanisms of borojo pulp (BPP), three borojo phases (liquid phase (LP), medium phase (MP) and solid phase (SP)), gum arabic (GA), and a mixture of these (BP) produced by freeze-drying were interpreted through adsorption isotherms. The adsorption models adequately describe the experimental data over the entire measured range of a w ; R 2 was close to 1 for the studied conditions. For the thermodynamic properties, the differential and integral enthalpy of BP showed a synergic effect of the combined components. This shows that using a combination of polymers increases the interaction energy of water molecules with the surface of the material. The monolayers from the BET and GAB models showed similar moisture content values that corresponded to the minimum integral entropy. Finally, the behavior of the enthalpy–entropy compensation of water adsorption for the SP, MP and GA powders at low moisture contents demonstrated that the content is controlled by an entropic mechanism, for BP, BPP and LP powders, the water adsorption may be considered as mainly enthalpy-driven.