“The results may have a definable impact on the design of ‘functional custards' with enhanced bioavailability,” wrote lead researcher Dr Teresa Sanz.
Custard, or crème-anglaise for the francophones, is a popular and well-accepted dessert in many countries. It is formulated by simply mixing milk, sugar and a thickening agent, with the different ingredients determining the structure and breakdown during digestion.
Making custard functional has already begun after Neptune Technologies & Bioressources announced in March that it has overcome barriers to incorporate Krill Oil (NKO) in custards, in alliance with Terepia.
And now researchers based at the Wageningen University and Research Center in the Netherlands, have reported that custard could be easily enriched with other bioactive ingredients, which turn the custard into a ‘functional food'.
"The innovation of this research was to evaluate if the type of thickening agent affect the 'bioaccessibility' or 'the release from the food matrix' of bioactive compounds. The results demonstrate that the type of thickening agent definitely affects the bioaccessibility," Dr Sanz told NutraIngredients.com.
Dr Sanz, under the supervision of Dr Hannemieke Luyten, investigated the effect of thickening agents on the release of two ingredients with known nutritional benefits: soy isoflavones and tyrosine (an antioxidant present in olive oil). The results are present in the journal Food Hydrocolloids (Vol. 20, pp. 703-711, 892-900).
The researchers formulated the tyrosol custards using four different thickening agents: modified waxy maize and tapioca (both starch thickeners) and CMC and HPMC (cellulose derived thickeners). Soy isoflavones (from the soy germ extract SoyLife Extra, Acatris) custards were formulated using modified waxy maize or CMC thickeners.
In vitro digestion conditions were simulated by creating conditions similar to the mouth (human saliva), the stomach (pepsin solution and hydrochloric acid, pH 2), and the small intestine (pancreatic extract and bile, trypsine, pH 6.5).
The recovery of the isoflavones from the custard after exposure to intestinal conditions, and therefore the ‘bioavailability' in the body, was found to be highest in the starch-based custards, compared to the CMC thickened custard (17.5 mg versus 11.0 mg). The presence of fat in the custard also reduced the availability of the isoflavones, reducing the release from 17.5 to 15.4mg for the starch custard, and 11.0 to 8.6 mg for the CMC custard.
“This implies that the CMC custard structure is still present after the complete digestion process and still acts as a hurdle for the release of isoflavones,” wrote Dr Sanz.
Dr Sanz said that the results confirm that starch custard could be a suitable vehicle to release isoflavones in the human body. She also stressed that when slow or restricted release of the active ingredient is required, then custards based on CMC may be preferred.
Similar results were obtained for the tyrosol with the starch-based custards showing significantly higher values of released tyrosol in the intestine model than the cellulose-based custards; for example, modified waxy maize starch releasing 100 per cent of the tyrosol (low consistency custard) compared to 67 per cent from the CMC custard and (low consistency).
“The cellulose custards, in particular the CMC ones, will be the correct choice in situations where due to unpleasant flavour and/or aroma a low release in the mouth is a primary concern,” explained Dr Sanz.
Sanz, now based at the Instituto de Agroquimica y Technologia de Alimentos, CSIC, in Spain, said that there has no been no contact from potential industrial partners, saying that the research has, to date, been purely academic.
