An extract from the leaves of the mulberry bush may act as a hydrocolloid, with potentially unique properties for food formulators, says new research from Taiwan.
A water extract of the mulberry leaf provided a hydrocolloid composed of mainly carbohydrate with high levels of uronic acid, indicating the ionic nature of the hydrocolloid, report the researchers in the journal Food Hydrocolloids.
"We found that mulberry leaf hydrocolloid possess unique rheology, particularly for the stiffer backbone as compared to other polysaccharide gums," wrote Hsiang-Yun Lin and Lih-Shiuh Lai from National Chung Hsing University.
"Furthermore, since the rheological properties of mulberry leaf hydrocolloid was strongly affected by the ionic strength and ion types, it is expected that rheological behavior of functional foods containing mulberry leaf hydrocolloids can be modulated by adjusting the ionic strength and ion types in food systems, and deserve further investigation to merit new application in the future."
The findings may be welcomed since the cost of nearly all hydrocolloids have increased in the last year due to rocketing energy, raw material and transportation costs, according to hydrocolloid information service IMR's Quarterly Review.
Emulsion stabilizers, suspending agents, gelling agents, thickeners, fiber sources, mouthfeel improvers, fat replacers and processing aids all come under the umbrella of hydrocolloids. This market has grown significantly in the past 20 years in parallel to an increasingly complex food processing industry.
The food industry's most frequently used hydrocolloids include: agar, alginates, arabic, carrageenan, Carboxy Methyl Cellulose (CMC), gelatin, konjac flour, locust bean gum (LBG), Methyl Cellulose and hydroxypropyl Methyl Cellulose (MC/HPMC), microcrystalline cellulose (MCC), pectin, starch and Xanthan.
A potential new member of this team, if further research backs up the promising early studies, could be hydrocolloid from mulberry leaves.
Characterization of mulberry hydrocolloid
Using deionized water, Lin and Lai prepared extracts of mulberry leaves. The average molecular weight of the carbohydrate part of thaws found to be 600,000, which was reportedly similar to values for low methoxy-pectin (540,000).
The relative chain stiffness parameters for the hydrocolloid were in the range of 0.004-0.013, which is indicative of a stiff backbone.
According to the researchers, studies on the rheological aspects of mulberry leaf hydrocolloid or relatively limited and this is one of the most extensive.
"During the development of functional foods containing mulberry leaf hydrocolloid or mulberry leaf extracts, viscometric properties should play an important role," they stated.
Source: Food Hydrocolloids
Published online ahead of print, doi: 10.1016/j.foodhyd.2008.03.018
"Isolation and viscometric characterization of hydrocoloids from mulberry (Morus alba L.) leaves"
Authors: H.-Y. Lin, L.-S. Lai