Effects of maltogenic α-amylase on physicochemical properties and edible quality of rice cake.

Maltogenic α-amylase (MA) are commercially used in the baking industry to retard starch retrogradation. However, whether MA can be used to modify rice flour during the fermentation process to improve the quality of rice flour remains unclear. In this study, MA was introduced during rice cake (RC) processing, and the modification effect and underlying mechanism were explored. Mn showed a decreasing trend except for 4.0 × 10-3 U/g sample. Chain length distribution data showed that MA effectively hydrolyzed long chains in amylopectin and increased the concentration of amylopectin chain length with a degree of polymerization of ≤ 9. High-performance liquid chromatography results suggested that the maltose content increased to 3.14% at an MA concentration of 9.5 × 10-3 U/g, which affected the fermentation effect of MA-treated RC. MA effectively reduced the viscosity of RC, and the gelatinization enthalpy of RC changed to 0.835 mJ/mg. MA also reduced the hardness and chewiness of RC after storage for 7 d. Moreover, rapidly digestible starch and slowly digestible starch contents of MA-treated RC decreased and increased, respectively, and resistant starch contents were remained unchanged. These results indicate that MA exerts a significant and effective antiretrogradation effect on RC. Combining the above results with sensory evaluation findings, an MA concentration of 4.0 × 10-3 U/g was the best supplemental concentration for obtaining RC with better edible quality. These findings suggest that MA treatment to rice flour during the fermentation process not only preserved the edible quality of RC but also retarded its retrogradation, thus, providing a novel processing method for the industrial production of RC.

Risk factors of early childhood caries (ECC) among children in Beijing - a prospective cohort study.

BACKGROUND: Early childhood caries (ECC) was a serious oral health concern with high prevalence and a low treatment rate in China, and few researches have focused on preschool children. This study aimed to explore the risk factors of ECC in Beijing, China. METHODS: Totle of 712 children (mean age: 46.37 ± 5.44 months) participated in this prospective cohort study. Questionnaires and the levels of mutans streptococci in dental plaques and non-stimulated saliva, assessed using Dentocult SM strips, were collected at baseline, respectively. Two calibrated examiners checked for dental caries according to the WHO 1997 criteria at baseline and 1-year follow-up. Negative binomial regression was used for multivariate analysis of factors related to caries development. RESULTS: For caries-free children at baseline, only plaque mutans streptococci (PMS) levels were associated with caries development (odds ratio [OR] = 1.68, 95% confidence interval [CI]: 1.08-2.61, P = 0.02). Children with high PMS levels (scored 2 and 3) had higher caries incidence (46.2% vs. 33.8%) and more caries increment (1.87 ± 3.17 vs. 0.90 ± 1.89) than those with low levels (scored 0 and 1). Among all participants, PMS (OR = 1.69, 95% CI: 1.32-2.23, P < 0.001) and previous caries experience (OR = 2.80, 95% CI: 2.20-3.56, P < 0.001) were related to caries increment. CONCLUSIONS: For caries-free children, the only significant risk factor for ECC was high PMS levels. For all participants, besides high PMS levels, previous caries experience was another significant risk factor for caries development. TRIAL REGISTRATION: The study design, protocol, and informed consent forms were undertaken with the understanding of Declaration of Helsinki and were approved by the Human Research Ethics Committee of the School of Stomatology, Peking University, China (PKUSSIRB-2012042).