Fermentation process for production of apple-based kefir vinegar: microbiological, chemical and sensory analysis

Abstract The aim of this study was to develop a kefir apple-based vinegar and evaluate this fermentation process using new methodology with Biospeckle Laser. Brazilian kefir grains were inoculated in apple must for vinegar production. In this study, the microbial community present in kefir, and correspondent vinegar, was investigated using Matrix Assisted Laser Desorption/Ionization - Time of Flight Mass Spectrometry (MALDI-TOF MS) technique. Saccharomyces cerevisiae, Lactobacillus paracasei, Lactobacillus plantarum, Acetobacter pasteurianus and Acetobacter syzygii were the microbial species identified. S. cerevisiae, L. plantarum, A. pasteurianus and A. syzygii were found in smaller quantities at the beginning of the alcoholic fermentation, but were found throughout the alcoholic and acetic fermentation. Kefir grains were able to utilize apple must as substrate to produce ethanol, and acetic acid. Acetate, volatile alcohols and aldehydes in the vinegar-based kefir were also produced. The yield of acetic acid in the kefir vinegars was ∼79%. The acetic acid concentration was ∼41 g L-1, reaching the required standard for the Brazilian legislation accepts it as vinegar (4.0% acetic acid). Kefir vinegar showed good acceptance in the sensory analysis. The technology proposed here is novel by the application of immobilized-cell biomass (kefir grains) providing a mixed inocula and eliminating the use of centrifuge at the end of the fermentative process. This step will save energy demand and investment. This is the first study to produce apple vinegar using kefir grains.

The use of halloysite clay and carboxyl-functionalised multi-walled carbon nanotubes for recombinant LipL32 antigen delivery enhanced the IgG response

We studied the feasibility of using halloysite clay nanotubes (HNTs) and carboxyl-functionalised multi-walled carbon nanotubes (COOH-MWCNTs) as antigen carriers to improve immune responses against a recombinant LipL32 protein (rLipL32). Immunisation using the HNTs or COOH-MWCNTs significantly increased the rLipL32-specific IgG antibody titres (p < 0.05) of Golden Syrian hamsters. None of the vaccines tested conferred protection against a challenge using a virulent Leptospira interrogans strain. These results demonstrated that nanotubes can be used as antigen carriers for delivery in hosts and the induction of a humoral immune response against purified leptospiral antigens used in subunit vaccine preparations.

A study of chlorophyll-like and phycobilin pigments in the C endosymbiont of the apple- snail Pomacea canaliculata

Pigments present in the brown-greenish C morph of an intracellular endosymbiont of Pomacea canaliculata were investigated. Acetone extracts of the endosymbiotic corpuscles showed an absorption spectrum similar to that of chlorophylls. Three fractions obtained from silica gel column chromatography of the acetone extracts (C I, C II and C III), were studied by positive ion fast atom bombardment-mass spectrometry (FAB-MS) and hydrogen-nuclear magnetic resonance (H-NMR). Results indicated the presence of (1) a sterol in the yellow colored C I fraction; (2) a mixture of pheophorbides a and b in the major green fraction, C II; and (3) a modified pheophorbide a in the smaller green fraction, C III. Aqueous extracts of the C endosymbiont did not show evidence of the occurrence of C-phycocyanin, allophycocyanin or phycoerithrin (light absorption, fluorescence emission, and electrophoresis of the protein moieties) while cyanobacterial cells (Nostoc sp.) showed evidence of C-phycocyanin and allophycocyanin. The possible phylogenetic and functional significance of the pigments present in the C endosymbiont is discussed.