Abstract:

The nutritional components of Abelia engleriana tender leaves as a potential source of functional foods
were analyzed, and gel extracts from these leaves were identified and measured for galacturonic acid content, degree of
esterification, aqueous solubility, gel characteristics and antioxidant activity. The results showed that the tender leaves
were rich in protein, crude polysaccharide, pectin, Ca, Fe, Zn, Se, β-carotene, pantothenic acid and seven kinds of essential
amino acids, thus having good nutritional value. The contents of crude polysaccharides, pectin and gel extracts were
5.68%, 15.9% and 21.69%, respectively. The gel extract from the tender leaves consisted mainly of crude polysaccharides
such as water-soluble high methoxyl pectin and exhibited good hydrophilicity and water holding capacity. It contained
68.72% galacturonic acid, and had a degree of esterification of 61.62% and an aqueous solubility of 98.63%. The firmness,
cohesiveness, consistency and viscosity index of the formed gel were negatively proportional to the amount of water used for
the extraction. Gels with good viscoelasticity and chewiness were obtained from the extraction at a water-to-solid ratio less
than 10:1. As the concentration of the extracted gel was increased up to 0.5 g/100 mL, its antioxidant capacity was enhanced,
while the upward trend slowed down and finally reached a plateau when the concentration exceeded 0.5 g/100 mL. Its
maximum 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability was 79.68%, and ferric reducing antioxidant
power (FRAP) 8.86 mmol/L. These results demonstrate that the tender leaves of Abelia engleriana have good nutritional
value and a strong antioxidant capacity, providing a source of useful ingredients in functional foods.

Key words: Abelia engleriana, nutritional component, gel, high methoxyl pectin, gel characteristics, antioxidant activity