Functional dissection of sweet and bitter taste pathways

Encapsulation of caffeine into starch matrices: Bitterness evaluation and suppression mechanism

In this study, caffeine (CA) was encapsulated into food-grade starch matrices, including swelled starch (SS), porous starch (PS), and V-type starch (VS). The bitterness of the microcapsules and suppression mechanisms were investigated using an electronic tongue, molecular dynamics (MD) simulation and the in vitro release kinetics of CA. All the CA-loaded microcapsules showed a lower bitterness intensity than the control. The MD results proved that the weak interactions between starch and CA resulted in a moderate CA release rate for SS-CA microcapsules. The PS-CA microcapsule presented the longest CA release, up to 40 min, whereas the VS-CA microcapsule completely released CA in 9 min. The CA release rate was found to be related to the microcapsule structure and rehydration properties. A low CA bitterness intensity could be attributed to a delay in the CA release rate and resistance to erosion of the microcapsules. The results of this work are valuable for improving starch-based microcapsules (oral-targeted drug-delivery systems) by suppressing the bitterness of alkaloid compounds.

Influences of non‐nutritive sweeteners on ovarian and uterine expression of T1R2 and T1R3 in peripubertal female guinea pigs

The underlying mechanism of taste receptor type 1 subunit 2 (T1R2) and taste receptor type 1 subunit 3 (T1R3) in the hormonal and reproductive system is still elusive. A low or a high dose of sweetness equivalent to that sodium saccharin (SS, 1.5 or 7.5 mM) and rebaudioside A (RA, 0.5 or 2.5 mM) was administered to young female guinea pigs for 28 consecutive days from the age of 28 days. Our results indicated that the sweet taste receptor subunit T1R2 was markedly expressed in the ovary and uterus of guinea pigs, whereas the T1R3 protein was expressed at a lower level. We elucidated that low-dose (1.5 mM) SS increased body and ovary weight associated with elevated ovarian expression of T1R2 in guinea pigs, unlike the high-dose (7.5 mM) SS, which suppressed the ovarian expression of T1R2 and resulted in certain adverse effects on ovarian and uterine morphology. Furthermore, high-dose (2.5 mM) RA increased the number of corpus luteum and elevated uterine expression of T1R2, whereas low-dose (0.5 mM) RA induced increased secretion of serum progesterone. Therefore, our findings suggest that we should pay more attention to the potential adverse effects, including increases in ovary weight, morphology changes, and increased progesterone that result from the dose-dependent regulation of T1R2 by non-nutritive sweeteners (NNS) in the ovaries and uteri of peripubertal females.

Effect of deamidation-induced modification on umami and bitter taste of wheat gluten hydrolysates

BACKGROUND

Bitter taste is the main limiting factor for various applications of protein hydrolysates. Frequently used physicochemical methods for debittering protein hydrolysates come with some undesired side effects. Deamidation-induced modification would be a very promising technique to improve the flavor of wheat gluten hydrolysates (WGHs). This study was designed to determine the effect of deamidation with certain enzymes or acid treatment on the chemical composition, bitterness and umami properties of WGHs. The difference between umami peptide and free glutamic acid on the suppression of bitterness is emphatically discussed. The optimal scheme is proposed based on the flavor of WGHs and the yield of peptides.

RESULTS

The generation of umami substances suppressed bitter signal transduction. When the content of umami substances was relatively high, the umami-enhancing properties of umami peptides were obviously effective. The intensity of umami taste was high enough to further suppress bitter taste in the course of neurocognitive functioning.

CONCLUSION

When WGHs were treated with Glutaminase for 180 min, the umami taste score increased from 1.62 to 4.27 and the bitter taste score decreased from 1.33 to 0.65. © 2016 Society of Chemical Industry.