Browsing by Author "Guo, Jiayue"

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    Inhibition of starch digestion by gallic acid and alkyl gallates
    (Elsevier, 2020-05) Gutierrez, Alyssa San Andres; Guo, Jiayue; Feng, Jiannan; Tan, Libo; Kong, Lingyan; University of Alabama Tuscaloosa
    As phenolic compounds, alkyl gallates may inhibit the activity of digestive enzymes for starch. Furthermore, their alkyl chains may facilitate starch inclusion complexation and results in an increased resistant starch (RS) content or slowly digestible starch (SDS) content, which may further retard starch digestion. The significance of such inhibition is that the rate of starch hydrolysis into glucose is reduced, thereby preventing hyperglycemia and related metabolic diseases. This study examined the inhibitory effects on in vitro enzymatic digestion of starch by gallic acid and five alkyl gallates of varying alkyl chain lengths, i.e., butyl gallate, octyl gallate, dodecyl gallate, hexadecyl gallate, and octadecyl gallate. Raw and cooked potato starch (PS) and high-amylose maize starch (HAMS) were tested. For both types of raw starch, gallic acid and all the alkyl gallates significantly (p < 0.05) increased RS content except for octadecyl gallate. In the case of cooked starch, the RS contents were markedly decreased (p < 0.05) as compared to those in raw starch, because gelatinization caused an overall greater susceptibility to enzymatic digestion. The reduction in RS content was less in cooked HAMS than that in cooked PS, due to a higher gelatinization temperature range of HAMS. The aforementioned effect of gallates on RS content was also found for cooked PS, while cooked HAMS experienced increased RS only with gallic acid and butyl gallate. Overall, for the digestion of both starches, regardless of raw or cooked, gallic acid and alkyl gallates with shorter chains demonstrated the strongest inhibitory effects. Our findings indicate that shorter alkyl gallates are effective in inhibiting enzymatic digestion of starch and therefore may have potential in modulating glycemic response.
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    Inhibitory Effect of Ascorbic Acid on in vitro Enzymatic Digestion of Raw and Cooked Starches
    (Frontiers, 2021) Guo, Jiayue; Gutierrez, Alyssa; Tan, Libo; Kong, Lingyan; University of Alabama Tuscaloosa
    Ascorbic acid, also known as vitamin C, was previously reported to inhibit the activity of pancreatic alpha-amylase, the primary digestive enzyme for starch. A major implication of such inhibition is a slowed rate of starch digestion into glucose, which thereby reduces postprandial hyperglycemia. The aim of this study was to explore the inhibitory effects of ascorbic acid at various concentrations on the in vitro digestion of high amylose maize starch (HAMS) and potato starch (PS) in both raw and cooked conditions. Resistant starch (RS) content, defined as the starch that remained after 4 h of simulated in vitro enzymatic digestion, was measured for the starch samples. Upon the addition of ascorbic acid, the RS contents increased in both raw and cooked starches. Cooking significantly reduced the RS contents as compared to raw starches, and less increase in RS was observed with the addition of ascorbic acid. The inhibitory effect of ascorbic acid on the digestion of raw starches showed a dose-dependent trend until it reached the maximum extent of inhibition. At the concentrations of 12.5 and 18.75 mg/mL, ascorbic acid exhibited the most potent inhibitory effect on the in vitro starch digestion in raw and cooked conditions, respectively. Overall, our results strongly indicate that ascorbic acid may function as a glycemic modulatory agent beyond other important functions, and its effects persist upon cooking with certain concentrations applied.
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    Microencapsulation of curcumin by spray drying and freeze drying
    (Elsevier, 2020-10) Guo, Jiayue; Li, Peilong; Kong, Lingyan; Xu, Baojun; University of Alabama Tuscaloosa; Cornell University; Beijing Normal University; Beijing Normal University - Hong Kong Baptist University United International College; Hong Kong Baptist University
    Curcumin is a natural pigment with health benefits and potential uses in food and pharmaceutical products, but its application is limited by its insolubility and instability. This study was to examine the effect of spray drying and freeze drying methods, as well as 12 combinations of ternary-composite wall materials, on microencapsulation efficiency (MEE), physicochemical properties (including particle size distribution, morphology, moisture content, and color values), and stability of curcumin against environmental stresses and in a model beverage. Curcumin encapsulated by freeze drying presented higher MEE, whereas spray drying produced microparticles of smaller particle size, smoother granule surface, and more regular shapes. Though to different extent, curcumin encapsulated by both methods exhibited improved stability against heat and acidity, and improved stability in a carbonated beverage. This study provides practical information on the selection of wall materials and encapsulation methods for microencapsulating curcumin for various applications.
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    Morphological and physicochemical characterization of starches isolated from chestnuts cultivated in different regions of China
    (Elsevier, 2019-06-01) Guo, Jiayue; Kong, Lingyan; Du, Bin; Xu, Baojun; Beijing Normal University - Hong Kong Baptist University United International College; Hong Kong Baptist University; University of Alabama Tuscaloosa; Hebei Normal University of Science & Technology
    This study was to compare the characteristics of 21 starches isolated from chestnuts produced in different regions in China, also to investigate their potential food applications. Starches were isolated from chestnuts under the Castanea mollisima Blume variety with sub-varieties of Banli, Youli, and Maoli. Several properties of the starch samples were examined, including the moisture content, amylose content, morphological characteristics, color values, light transmittance, syneresis, swelling power, water solubility index, pasting properties, FTIR characteristics, X-ray diffraction (XRD) patterns, and thermal properties. The results showed that starches isolated from Youli presented higher resistance to shear and swelling during heating, indicating more suitability for high heat cooking. The FTIR spectra confirmed the polysaccharide nature of all the chestnut starches. The XRD patterns showed most chestnut starches were in C-b-type, while only five were in C-a-type. Overall, this comparative study would be relevant for the further exploration of the potential utilization of chestnut starch in both food and nonfood industries. (C) 2019 Elsevier B.V. All rights reserved.
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    Structure-Digestibility Relationship in V-Type Inclusion Complex and its Potential As a Novel Type of Resistant Starch
    (University of Alabama Libraries, 2022) Guo, Jiayue; Kong, Lingyan; University of Alabama Tuscaloosa
    As the non-digestible portion of starch, resistant starch (RS) has been associated with many health beneficial effects such as modulating glycemic response and improving gut health. Among several types of RS, a novel type, i.e., RS5, has attracted more attention in recent years due to its high thermal stability and added functionality. The main objective of this study is to develop a V-type starch inclusion complex with retarded digestibility and low glycemic index (GI) as a novel RS5 and elucidate the structure-digestibility relationship in starch inclusion complex formed using different preparation methods and hydrothermal treatments. The starch inclusion complex of interest in this study is that formed with a bioactive guest compound, ascorbyl palmitate (AP). First, AP was shown to significantly reduce the in vitro digestibility of raw, cooked, and retrograded high amylose maize and potato starch. Then, its inclusion complexes with starch were prepared using two methods, i.e., the dimethyl sulfoxide (DMSO) method and the novel “empty” V-type method, and several hydrothermal treatments were applied. Although minimal RS content was present in the raw inclusion complex samples prepared by both methods, hydrothermal treatments significantly increased the RS content. Among all, annealing followed by strong acid hydrolysis (ANN-ACH) was the most effective treatment in enhancing RS content. Lastly, the ANN-ACH starch-AP inclusion complex was further examined for its hydrolysis pattern and GI in both in vitro and in vivo experiments. Consistent results were obtained that this inclusion complex showed the least glucose release and the lowest GI value, falling within the range of low GI foods. The in vivo GI was even lower than that of the raw high amylose maize starch (RS2), indicating its more pronounced effect in modulating the postprandial glycemic response in mice. In combination of the high RS content, moderate hydrolysis pattern, low GI value, and the distinctive V-type crystalline structure, the ANN-ACH treated starch-AP inclusion complex could provide potential beneficial effects on health. Future research is warranted to explore the potential ways of incorporating such ingredient in food products and the long-term effect of such novel RS5 for the prevention and treatment of chronic diseases.