Understanding the key interactions of additives in a food matrix is vital for manufacturers seeking to develop new formulations or improve established ones, and the new research published in the Journal of Texture Studies goes some way to filling in the gaps.
Researchers from North Carolina State University studied the effects of dextran and glycerol on the rheological characteristics of alginate gels and found that the molecular size of an additive should be considered by formulators.
“The inclusion of additives may affect physical and chemical properties of the gels, and subsequently, the rheological properties,” wrote the authors
“Rational optimization of product formulations and processing conditions of food gels depends on a better understanding of the impact of additives on processing and rheological properties,” they added.
Gelling agents fall under the hydrocolloids umbrella - ingredients used extensively by the food industry to texturise and stabilise food products from dressings to ice cream. Though these products are sensitive to spiralling raw material costs, the demand for hydrocolloids remains impressive.
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.
On addition of glycerol, a plasticiser commonly used to enhance the mechanical performance of food gels, the researchers report no effects on the gel-forming process, or the gel mechanical performance.
“These observations indicated that the gel network remained unchanged with the addition of glycerol,” wrote the researchers.
“In this alginate study, glycerol did not appear to have a plasticising effect because mechanical properties did not change with glycerol addition,” they added.
For dextran, the North Carolina-based researchers tested both low and high molecular weight (MW) types. While the low MW dextran was reported to have similar effects to glycerol, the high molecular weight dextran was found to change certain parameters associated with gel strength, including the a reduction in the so-called gel fracture stress and deformation properties.
“This response was hypothesised as a result from the large dextran molecules affecting network structure, and not due to the influence of high MW dextran on liquid phase viscosity,” they stated.
Growth in the seaweed market
According to Leatherhead Food International (LFI), alginates are predominantly used in the food industry in ice cream and desserts, bakery creams, sauces and dressings, glazes and fillings, and some beverages.
The global market for seaweed-derived hydrocolloids is estimated to be around $700m, with carrageenans representing 60 per cent of this, and alginates representing about 20 per cent.
Source: Journal of Texture StudiesVolume 39 Issue 5, Pages 582 – 603"Additive effects on the rheological behavior of alginate gels"Authors:J. Zhang, C.R. Hang, C.R. Daubert, J.H. Mulligan, E.A. Foegeding