Polyphenol-fortified extruded sweet potato starch vermicelli: Slow-releasing polyphenols is the main factor that reduces the starch digestibility.

To investigate the digestive behavior of extruded starch-polyphenols system, extruded sweet potato starch vermicelli (ESPSV) was used as a model. The multi-scale structure, starch digestibility, polyphenol release, digestive enzyme activity during digestion and their correlation of ESPSV supplemented with matcha (MT), green tea extract (GTE), tea polyphenols (TP) and epigallocatechin gallate (EGCG) (at 1% polyphenol level) were discussed. Results showed that tea products in whatever form could retard starch digestion, with EGCG working best. The predicted glycemic index (pGI) of ESPSV was decreased from 82.50 to 65.46 after adding EGCG. Starch formed larger molecular aggregates with tea products under extrusion, showing a "B + V" type pattern. The order of V-type crystals content was EGCG + ESPSV (1.41) > TP + ESPSV (1.50) > GTE + ESPSV (1.88) > MT + ESPSV (2.62) > ESPSV (3.20). Under external pressure, EGCG, as tea monomer, was more likely to enter the spiral cavity of amylose and form V-type inclusion complex. Notably, polyphenols released during digestion could still reduce digestive enzyme activity, with a 15.53% decrease in EGCG + ESPSV compared to ESPSV. This was verified by correlation analysis, where RDS content (0.961, p < 0.01) and pGI (0.966, p < 0.01) were highly significantly correlated with the enzyme activity. Furthermore, tea products did not break or even enhance the quality of ESPSV as the final product.

Peptide photowrapping of gold-silica nanocomposites for constructing MMP-responsive drug capsules for chemo-photothermal therapy.

A multifunctional undecapeptide, YYDPLGLADYY, was designed and synthesized for the photowrapping of silica-coated gold nanorods. The obtained nanocapsules, bearing a well-defined core-shell structure, were able to encapsulate a therapeutic drug, respond to an MMP-upregulated tumor microenvironment, and achieve NIR-triggered anticancer chemo-photothermal therapy with favorable efficacy.

Collagen hydrolysates improve the efficiency of sodium alginate-encapsulated tea polyphenols in beads and the storage stability after commercial sterilization.

This study showed that sodium alginates (SA)-based beads reinforced with collagen hydrolysates (CHs) significantly increased an encapsulation rate of tea polyphenols (TP) from 34.54 % to 85.06 % when the mass ratio of SA: CHs increased from1.5:0 to 1.5:0.5. And after the 30-day storage at 37 °C, the retention rate of TP in beads with CHs at the solutions with pH = 4.0 or pH = 7.0 increased from 61.10 % to 80.21 %, or from 67.72 % to 80.47 % after sterilization at 98 °C or 121 °C for 30 min, respectively. Also, the addition of CHs at 0.5 % resulted in a greater retention of the polyphenolic compositions values of TP determined by UPLC-Orbitrap-MS system. Additionally, the DPPH and ABTS+ free-radical scavenging capacities and ferric-reducing antioxidant power of beads with CHs after sterilization at 98 °C or 121 °C for 30 min were significantly higher than which without CHs. Physical phenomena based on ζ-potential, particle size, fluorescence, UV spectroscopy and confocal laser scanning microscope showed that tightly non-covalent complexes of CHs in combination to TP could be uniformly and stably distributed in the network of SA solution for encapsulating TP in SA-based beads. These findings provided suggestions for the co-encapsulation design and development of hydrophilic nutritive compounds based on CHs in SA-based beads.

The effect of different tea products on flavor, texture, antioxidant and in vitro digestion properties of fresh instant rice after commercial sterilization at 121 °C.

The conventional process of commercial sterilization at 121 °C resulted in undesirable flavor, injured texture and fast starch digestion of fresh instant rice (FIR) with non-dehydration. In this study, tea products, such as instant green tea (IGT), instant black tea (IBT) and matcha (Mat) were chosen as ingredients to improve the quality of FIR. The results showed thatadding tea products endowed FIR with subtle flavors and higher antioxidant capacity. And the data of XRD, FTIR and SEM indicated that the improved texture of FIR with suitable chewiness was attributed to the stability of non-crystal structure. Furthermore, compared with IBT and Mat, IGT increased the ability against digestion from 10.18% to 30.44% and delayed the retrogradation rate from 18.89% to 4.38% evidenced by T2 values after stored for 14 d. Therefore, adding tea products will be a new way to improve the quality of FIR.

Effects of tea products on in vitro starch digestibility and eating quality of cooked rice using domestic cooking method.

Cooked rice (CR) is a staple diet for many people, but exhibits the high glycemic index that makes it difficult to control the blood glucose. Herein, instant green tea (IGT), instant black tea (IBT) and matcha (Mat) (1, 2 and 3% w/w, rice basis) were added to lower the in vitro starch digestibility and improve the eating quality of CR prepared with an electric rice cooker. The results showed that adding tea products at each level could remarkably reduce the in vitro starch digestibility of CR. Compared with IGT and IBT, 3% of Mat significantly decreased the contents of rapidly digestible starch (RDS) from 72.96% to 60.99%, the digestion rate constant (K) from 11.4 × 10-2 to 8.68 × 10-2 min-1 and the expected glycemic index (eGI) from 77.55 to 66.86. Furthermore, the gas chromatography-ion migration spectrum was analysed to confirm that the tea products endowed the cooked rice with a refreshing flavor by inducing the redistribution of the main aroma components. Moreover, it was found that increasing the ordered crystal structure of rice grains played a major role on lowering the starch digestion, which was demonstrated by the results of the Rapid Visco Analyser, scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. These findings suggested that cooking rice with tea products, especially Mat, can be useful in enhancing the palatability and slowing the in vitro digestion properties of CR.

Inhibition of gelatinized rice starch retrogradation by rice bran protein hydrolysates.

The retrogradation of gelatinized rice starch (GRS) during the shelf life of a product is the biggest barrier related to starch-containing foods. The objective of this study was to produce rice bran protein hydrolysate (RBPH) using proteolytic enzymes (alcalase, flavourzyme, protamex, neutrase, bromelain, papain and trypsin) to suppress the retrogradation of GRS and understand the physical phenomena underlying the reduced retrogradation of GRS by RBPH during short- and long-term storage. Mixtures of GRS incorporated with Protamex-hydrolyzed rice bran protein at 1h (PRBPH-1) at a degree of hydrolysis of 15.1% were still fresh after storage at 4°C for 14 d. The dynamic time sweep results obtained at 4°C for 180min showed that PRBPH-1 reduced the storage modulus to a greater extent, indicating that PRBPH-1 suppressed the short-term retrogradation of GRS. Differential scanning calorimetry (DSC) clearly showed that PRBPH-1 significantly decreased the retrogradation enthalpy during the 28-d storage at 4°C, and the retrogradation kinetics were analyzed by the Avrami model. In addition, the recrystallization of GRS based on X-ray diffraction spectroscopy was reduced from 15.41% to 4.86% when the GRS: PRBPH-1mass ratio increased from 100:0 to 100:12. Confocal laser scanning microscopy, atomic force microscopy and scanning electron microscopy demonstrated that PRBPH-1 dispersed between GRS molecules to block the formation of hydrogen bonds to inhibit the recrystallization of GRS. These findings suggested that PRBPH-1 inhibited the short- and long-term retrogradation of GRS, and can be potently employed as a natural alternatives for improving the quality and nutrition of starch-containing foods.