Sugar molecules stability

A polymer is a molecule that consists of a long chain of small molecules (monomers) that are linked together. The stabilizers used in cream are mostly polysaccharides, i.e. polymers of sugar molecules. Stabilizers have a number of functions, one of which is to increase the viscosity of ice cream mixes. Figure 2.15 shows the viscosity of a typical polymer solution as a function of concentration. The polymer increases the solution viscosity at low concentrations, and, above a certain concentration, the viscosity increases even more rapidly. 

A typical characteristic of many food products is that these are multi-phase products. The arrangement of the different phases leads to a microstructure that determines the properties of the product. Mayonnaise, for example, is an emulsion of about 80% oil in water, stabilized by egg yolk protein. The size of the oil droplets determines the rheology of the mayonnaise, and hence, the mouthfeel and the consumer liking. Ice cream is a product that consists of four phases. Figure 1 shows this structure schematically. Air bubbles are dispersed in a water matrix containing sugar molecules and ice crystals. The air bubbles are stabilized by partial coalesced fat droplets. The mouthfeel of ice cream is determined by a combination of the air bubble size, the fat droplet size and the ice crystal size. 

This enzyme exhibits no hydroxylase activity and is involved in the final synthesis of many naturally occurring /t-quinoncs. e.g. the naphthaquinone juglone in walnut (1.58) and the benzoquinone arbutin (hydroquinone-(3-D-glucopyranoside 2.46). Arbutin is a plant cryo-protectant that stabilizes membranes (Hincha et al., 1999). This compound has medicinal properties and has, for example, been used to treat urinary tract infections in humans. It is also used to lighten skin color, because it inhibits tyrosinase and hence the formation of melanin. The derivative deoxyarbutin (2.47 note the difference in the sugar molecule) was recently reported to be considerably more effective as a skin-lightening compound (Boissy et al., 2005). 

It is well known that glycosylated proteins are very stable, therefore grafting polysaccharides or short chains of sugar molecules onto proteins has been used to improve enzyme stability. (6,7,8)... 

The subtle differences between sugar molecules which cause such dramatic effects (Le. Dulcitol verses sorbitol) are possibly caused by adverse interactions either with water or the amino acids of the protein. It is possible that under certain conditions the position of hydroxyl groups causes strong binding of water and leads to confirma-tional distortion of the protein rather than stabilization. Monsan and Combes (13) have suggested that this is due to excessive binding to the stabilizer thus disrupting the protein surface/water interactions. As yet we have no evidence to further elucidate this theory. 

Currently, the mechanism of biological nanoparticle synthesis is not fully understood. For gold nanoparticles synthesized extracellularly by the fungus F. oxyspo-rum, it was reported that the reduction occurs due to NADH-dependent reductase released into the solution [16]. With neem leaf broth, it was reported that terpenoids are believed to be the surface-active molecules stabilizing the nanoparticles, and reaction of the metal ions is possibly facilitated by reducing sugars or terpenoids... 

A similar rationale can be made for the 5-membered intermediate. The glucose derivative dehydrates to a 4-fiiranone. 4-Furanone is a relatively labile substance llich can be found only in monosaccharide reaction mixtures. In the fiiranoid structure which is derived from disaccharides, the bound sugar prevents this reaction and the molecule stabilizes itself by forming a 3-friranone (Figure 4). Recently we were able to isolate 3-fiiranone (7) and establish its structure by spectroscopic data (P). 

---