Microwave-assisted methanolysis of green coffee oil

AbstractOptimisation of a microwave-assisted methanolysis was performed to obtain cafestol and kahweol directly from green coffee oil (Coffea arabica). A two-factor (the methanolysis period and temperature), three-level, factorial experimental design (32) was adopted. The methanolysis procedure was performed under microwave irradiation, using closed vessel and accurate fast responding internal fibre-optic temperature probe. The effects on the responses were measured by HPLC. After 3min of microwave irradiation (hold time) at 100°C, with 500mg of green coffee oil, a yield higher than 99% was obtained. The yield of this reaction is 26% after 2h when working under conventional heating. The methods described in the literature lead to long reaction times, poor yields and formation of side products. The microwave-assisted technique proved to be faster, avoided undesired side products and gave better conversion, when compared to conventional heating process

Water-in-oil-in-water double emulsions as protective carriers for Sambucus nigra l. coloring systems

The use of natural colorants is needed to overcome consumer concerns regarding synthetic food colorants0 safety. However, natural pigments have, in general, poor stability against environmental stresses such as temperature, ionic strength, moisture, light, and pH, among others. In this work, water-in-oil-in-water (W1/O/W2) emulsions were used as protective carriers to improve color stability of a hydrophilic Sambucus nigra L. extract against pH changes. The chemical system comprised water and corn oil as the aqueous and oil phases, respectively, and polyglycerol polyricinoleate (PGPR), Tween 80, and gum Arabic as stabilizers. The primary emulsion was prepared using aW1/O ratio of 40/60 (v/v). For the secondary emulsion,W1/O/W2, different (W1/O)/W2 ratios were tested with the 50/50 (v/v) formulation presenting the best stability, being selected as the coloring system to test in food matrices of different pH: natural yogurt (pH 4.65), rice drink (pH 6.01), cow milk (pH 6.47), and soy drink (pH 7.92). Compared to the direct use of the extract, the double emulsion solution gave rise to higher color stability with pH change and storage time, as corroborated by visual and statistical analysis.FCT/MCTES for financial support to CIMO (UIDB/00690/2020). National funding by FCTFoundation for Science and Technology, through the institutional scientific employment programcontract of A. Fernandes, I. Fernandes, and L. Barros. Valor Natural project (Project Norte-01-0247- FEDER-024479).info:eu-repo/semantics/publishedVersio