Single crystals of cuprorivaite (CaCuSi 4 O 10 ), one of the oldest synthetic color pigments of Egyptian history, have been synthesized by slow-cooling flux method. Several runs were carried out at temperatures between 800 and 960°C and with reaction times ranging from 10 to 72 h. The starting materials and run products were characterized by binocular microscope, X-ray powder diffraction, scanning electron microscopy with annexed energy-dispersive spectrometry, and l-Raman spectroscopy. The effects of growth parameters (temperature, flux, silica source) on yield and size of crystals were studied. The growth of cuprorivaite depends greatly on the starting materials: they are observed as run products only using natron as flux. Furthermore, colorimetric analysis performed on the synthesizing pigment was compared with the archeological samples present in the literature in order to value similarities and differences.

Camel milk isolates of lactic acid bacteria were characterized to develop defined starter cultures that could be used for the production of standardized Egyptian Rayeb fermented milk. The isolates have shown a wide diversity of Technological characteristics and antimicrobial activity. Interesting isolates were genetically identified at the species level. Two mixed culture starters composed of Lactiplantibacillus plantarum (FFNL146 and FFNL159) and Lactococcus lactis (FFNL1926 and FFNL2005) along with Leuconostoc pseudomesenteroides FFNL2374 were used in the production of Rayeb from camel milk, cow milk, and their mixture and stored for 14 days under refrigeration. Equally mixed camel and cow milk fermented with both starters had the best results of organoleptic attributes and physicochemical properties compared to samples made of camel milk. This is the first study to present two mixed starter cultures for Rayeb manufacturing. The success of these defined starter cultures will potentially enhance the safety and quality of the Rayeb industry in Egypt.