GLOSSARY

Hemicellulose names a diverse family of plant-cell-wall polysaccharides, not an incomplete or half-sized cellulose. Types such as cereal arabinoxylans differ in structure, solubility and fermentation.

Plant cell walls form networks of cellulose, hemicelluloses, pectin and other components whose proportions vary across tissues. These networks can affect release of food components during chewing and digestion. Lignin can accompany them but is not chemically a polysaccharide; not every component in a matrix is the same carbohydrate type.

Carbohydrate structure involves more than the number of sugar units: bond type and molecular arrangement also matter. Starch and cellulose both contain glucose, yet human enzymes do not break them down in the same way. Polymer status or chain length alone therefore does not determine digestion rate or nutritional value.

Solubility, viscosity and fermentability are separate properties. Inulin can be soluble, low-viscosity and readily fermented; psyllium forms gels but is generally less fermented. Two ingredients described as soluble fibre therefore need not produce the same intestinal consistency, gas production or post-meal response.