Fayin Ye

Phenolic profile and in vitro antioxidant capacity of insoluble dietary fiber powders from citrus (Citrus junos Sieb. ex Tanaka) pomace as affected by ultrafine grinding.

The effects of mechanical and jet grindings on the proximate composition, phenolics, and antioxidant capacity of insoluble antioxidant dietary fiber powder from citrus pomace (IADFP-CP) were investigated in comparison with ordinary grinding. IADFP-CP from jet grinding showed higher levels of crude fat, total sugar, and free phenolics and lower levels of crude protein and bound phenolics than that from ordinary grinding. Totally, 14 phenolics (9 free, 1 bound, and 4 free/bound) in IADFP-CP were identified by RP-HPLC-DAD/ESI-Q-TOF-MS/MS. Hesperidin accounted for >57% of total phenolics in IADFP-CP. Among IADFP-CPs, the jet-ground presented the highest free phenolics but the lowest bound phenolics. The IADFP-CP from jet grinding presented the highest antioxidant capacity of free phenolics (by DPPH and FRAP assays), followed by the ones from mechanical and then ordinary grinding. The present study suggests that jet grinding could improve the extraction of phenolic compounds from IADFP-CP and increase the antioxidant capacities of free phenolics and the resultant powder.

Adsorption characteristics of rebaudioside A and stevioside on cross-linked poly(styrene-co-divinylbenzene) macroporous resins functionalized with chloromethyl, amino and phenylboronic acid groups.

The adsorptive separation of each steviol glycoside from aqueous solutions by polymeric adsorbents has attracted a lot of interest in recent years. The adsorption properties of chloromethylated cross-linked poly(styrene-co-divinylbenzene) macroporous resins, functionalised with chloromethyl, amino and phenylboronic acid groups, towards rebaudioside A and stevioside were studied. The results revealed that the resins with amino and phenylboronic acid groups preferred to adsorb stevioside rather than rebaudioside A, and their adsorption kinetics fitted a pseudo-second-order model. Isothermal equilibrium curves of rebaudioside A and stevioside showed a good fitness with the Langmuir and Freundlich models. The adsorption of rebaudioside A and stevioside onto resins was a spontaneous and exothermic process as indicated by the negative values in free energy and enthalpy. Results from the resin-packed column demonstrated that an effluent rich in rebaudioside A (purity 98%) was obtained prior to the breakthrough point of stevioside.

Lignin from bamboo shoot shells as an activator and novel immobilizing support for α-amylase

This study examined the feasibility of α-amylase activation and immobilization, using lignin from bamboo shoot shells (BSS). Our results demonstrated that BSS lignin is an excellent α-amylase activator and it elevated α-amylase activity more than two-fold at a concentration of 5mg/ml. For immobilization of α-amylase via adsorption, BSS lignin was incubated in an α-amylase solution (5mg/ml) for 20min, and the maximum specific activity, amount of loaded protein and activity recovery were 92.4U/mg, 19.0mg/g and 111%, respectively. In contrast to its free counterpart, immobilized α-amylase improved the catalytic efficiency and storage stability, under comparable working conditions (temperature and pH). Regarding its convenient usage, immobilized enzyme can be suspended in advance, but a suspension incubated at 60°C should be used within 30min. The residual activity after 14 re-uses remained at a reasonable level (53.2%). In conclusion, this study reveals a novel support for enzyme immobilization.

Effect of micronization on the physicochemical properties of insoluble dietary fiber from citrus (Citrus junos Sieb. ex Tanaka) pomace

The aim of this work was to study the effect of micronization (mechanical and jet grindings) on the physicochemical properties of the insoluble dietary fiber from citrus pomace in comparison with ordinary grinding. The results showed that micronization treatment effectively pulverized the IDF-CP powders to micron scale and significantly increased the soluble dietary fiber content (p < 0.05). Compared with mechanical grinding, jet grinding was more effective in size reduction and resulted in IDF-CP powders with narrower particle size distributions. Micronized IDF-CP powders had smaller particle size, smoother surface, higher fluidity, cation-exchange capacity, and metal cation binding capacity values, but lower water holding capacity, oil holding capacity, and swelling capacity values. These functional properties were significantly dependent on surface area and particle size (D0.5). The present study suggested that micronization treatments could modify functional properties of IDF-CP powders, which promotes their use in food applications.

Synthesis and characterization of a novel antioxidant RS4 by esterifying carboxymethyl sweetpotato starch with quercetin

Quercetin is grafted to carboxymethyl sweetpotato starch (CMSS) by esterification. Upon esterification, the water solubility of CMSS decreases and the CMSS-quercetin conjugates (CMSS-Q) are yellowish. FT-IR and 1H NMR indicated the covalent attachment of quercetin to CMSS. Thermogravimetry revealed the superior thermal stability of CMSS-Q over CMSS and native sweetpotato starch (NSS). The in vitro digestibility assays showed that CMSS is highly resistant to digestion while the quercetin graft with degree of substitution (DS) above 0.074 slightly increased its digestibility. The quercetin graft imparted CMSS with strong antioxidant activity and enhanced its thermal stability, which increased with quercetin DS. In vitro cyotoxicity assessment revealed that CMSS-Q is as safe as CMSS and NSS. This study showed that CMSS-Q is a novel antioxidant-resistant starch in RS4 form.

Synthesis and Characterization of Fatty Acid Oat β-Glucan Ester and Its Structure–Curcumin Loading Capacity Relationship

An amphiphilic fatty acid oat β-glucan ester (FAOGE) was first synthesized, and its structure-curcumin loading capacity (CLC) relationship was investigated. The DS of product increased with the addition of acyl imidazole, decreased with Mw of β-glucan, and did not relate to the acyl chain length. Characterizations by FT-IR and (1)H NMR evidenced the presence of ester groups in FAOGE and confirmed its successful synthesis. The aqueous self-aggregation behavior of FAOGE was revealed by transmission electron microcopy and dynamic light scattering. With the aid of response surface methodology, a quadratic polynomial equation was obtained to quantitatively describe the structure-CLC relationship of FAOGE by using Mw of β-glucan, acyl chain length, and DS as variables. The CLC increased with Mw of β-glucan and acyl chain length but maximized at a medium DS. The maximum CLC value was obtained as 4.05 μg/mg. Hence, FAOGE is a potential candidate in solubilizing and delivering hydrophobic food ingredients.

Interactions of ε-polylysine with carboxymethyl sweet potato starch with an emphasis on amino/carboxyl molar ratio.

The interaction between ε-polylysine (ε-PL) and anionic polysaccharides has gained considerable attention recently because of its scientific impact on the stability and appearance of liquid food systems. The purpose of this study was to characterize the interactions between ε-PL and carboxymethyl sweet potato starch (CSS) using isothermal titration calorimetry (ITC), electrical charge, and turbidity measurements. The results showed that the interaction between ε-PL and CSS was electrostatic and mainly dependent on the molar ratio of amino groups in ε-PL to carboxyl groups in CSS. Additionally, the interaction between ε-PL and CSS was also associated with pH, degree of substitution (DS) of CSS, and ionic strength of the system. For the interaction of ε-PL with high DS (>0.235) CSS, three states of the ε-PL/CSS mixture were observed as transparent, turbid, and precipitated with a successive increase in amino/carboxyl molar ratio. Distinguishingly, a transparent mixture could be obtained for CSS with low DS (0.114) at a sufficiently high amino/carboxyl molar ratio. The present study provided basic guidance in designing liquid food systems containing both ε-PL and CSS.

The effects of oat β-glucan incorporation on the quality, structure, consumer acceptance and glycaemic response of steamed bread

The objective of this study was to evaluate the effects of the incorporation of oat β-glucan (OβG) on the sensory and nutritional quality of steamed bread. Wheat flour was substituted with OβG at levels varying from 0 g/100 g to 5 g/100 g. The results showed that the products containing 1 g/100 g and 3 g/100 g OβG produced a comparable overall consumer acceptance while a significantly lower score was given to the product with 5 g/100 g. Nutritionally, the presence of OβG impeded in vitro starch hydrolysis by amylolytic enzymes. More importantly, the addition of OβG up to 5 g/100 g did bring about a lower in vitro predicted glycaemic index to steamed bread, but it generated insignificant effects on the in vivo glycaemic response. The current work first demonstrated the feasibility of fabricating OβG-enriched steamed bread and its nutritional superiority compared to the corresponding normal product. PRACTICAL APPLICATIONS Modern methods of food elaboration and processing frequently reduce the content of dietary fiber (DF). Despite the well-known health benefits of DF consumption, average intake levels still fall far below recommended ones. Oat β-glucan (OβG) is a kind of indigestible polysaccharide with diverse bioactivity. This article evaluated the effects of OβG incorporation on quality, structure, consumer acceptance, and glycaemic response of steamed bread. The addition of less than 3 g/100 g of OβG had negligible effects on the consumer acceptance of steamed bread. The enrichment at 5 g/100 g indeed deteriorated the consumer acceptance. Moreover, OβG highly lowered the glycaemic response of steamed bread. The current work first demonstrated the feasibility of fabricating OβG-enriched steamed bread and its nutritional superiority compared to the corresponding normal product. OβG enriched steamed bread may offer an alternative to improve DF intake of residents.

Dietary Flavonoids and the Risk of Colorectal Cancer: An Updated Meta-Analysis of Epidemiological Studies

Aim: The aim of this study was to perform an up-to-date meta-analysis of the association between the intake of dietary flavonoids and the risk of colorectal cancer. Methods: The PubMed and EMBASE databases were searched to identify eligible studies. The risk of colorectal cancer for the highest versus the lowest categories of flavonoids intake were assessed. Results: A total of 12 studies (5 cohort and 7 case-control studies) involving 17,481 cases and 740,859 controls were eligible for meta-analysis. High intake of dietary flavonols, flavones and anthocyanidins may decrease the risk of colorectal cancer; the pooled odds ratio (OR) for the highest intake compared with the lowest was 0.70 (0.54–0.90), 0.79 (0.83–0.99) and 0.78 (0.64–0.95), respectively. No association between the intake of total flavonoids, flavanones or flavan-3-ols and the risk of colorectal cancer was observed. Furthermore, the data showed that high intake of flavonols may decrease the risk of colon cancer [0.80 (0.68–0.94)] but not rectal cancer [0.93 (0.74–1.18)], while on the contrary, the intake of flavones may decrease rectal cancer risk [0.82 (0.70–0.97)] but not colon cancer risk [0.88 (0.69–1.13)]. Conclusions: The present study suggested that high intake of flavonols (such as quercetin) may reduce the risk of colon cancer, and high intake of flavones (such as apigenin) may reduce the risk of rectal cancer.

Joint Effects of Granule Size and Degree of Substitution on Octenylsuccinated Sweet Potato Starch Granules As Pickering Emulsion Stabilizers

The granules of sweet potato starch were size fractionated into three portions with significantly different median diameters ( D50) of 6.67 (small-sized), 11.54 (medium-sized), and 16.96 μm (large-sized), respectively. Each portion was hydrophobized at the mass-based degrees of substitution (DSm) of approximately 0.0095 (low), 0.0160 (medium), and 0.0230 (high). The Pickering emulsion-stabilizing capacities of modified granules were tested, and the resultant emulsions were characterized. The joint effects of granule size and DSm on emulsifying capacity (EC) were investigated by response surface methodology. For small-, medium-, and large-sized fractions, their highest emulsifying capacities are comparable but, respectively, encountered at high (0.0225), medium (0.0158), and low (0.0095) DSm levels. The emulsion droplet size increased with granule size, and the number of freely scattered granules in emulsions decreased with DSm. In addition, the term of surface density of the octenyl succinic group (SD-OSG) was first proposed for modified starch granules, and it was proved better than DSm in interpreting the emulsifying capacities of starch granules with varying sizes. The present results implied that, as the particulate stabilizers, the optimal DSm of modified starch granules is size specific.