Effects of Incorporated Emulsifiers Into Noodles on V-amylose Formation, Digestibility, and Structural Characteristics.

There is growing interest in developing low glycemic alternatives to starchy foods. In this study, two emulsifiers, namely sodium stearoyl lactylate and egg yolk, were incorporated into the formulation of noodles (EYN and SSLN), and their effects on V-amylose formation, digestibility and structural characteristics of the noodles were investigated. The emulsifiers facilitated V-amylose formation in the noodles, indicated by the complexing indices. The EYN and SSLN exhibited markedly high resistant starch contents compared to the control noodle. The logarithm of slope plot analysis showed that the EYN and SSLN had low first-phase rate constants compared to the control noodles, suggesting a barrier effect to digestive enzymes exerted by V-amylose. The SSLN and EYN displayed a mixture of B- and V-type patterns with higher crystallinities and two distinct spectral features of the bands at 2854 cm- 1 and 1746 cm- 1 compared to the control noodles. Polarized light micrographs of the SSLN and EYN exhibited vague contours of numerous irregularly shaped starch fragments with strong birefringence. These results suggest that forming V-amylose crystals in the SSLN and EYN was responsible for their increased resistance to digestion through reformulating emulsifiers in modifying their nutritional functionalities.

Effects of Debranching Conditions and Annealing Treatment on the Formation of Starch Nanoparticles and Their Physicochemical Characteristics.

Starch nanoparticles (SNPs) have unique attributes that make them suitable for specific applications. In this study, we assessed the optimum conditions for the fabrication of SNPs from the rice starches of low- (TCSG2) and medium-amylose rice lines (TK11) using pullulanase debranching combined with annealing treatment and evaluated their physicochemical and digestion properties. The highest crystalline SNP percent recoveries of 15.1 and 11.7% were obtained from TK11 and TCSG2, respectively, under the following debranching conditions: 540-630 NPUN/g, pH 5.0, 60 °C, and 12 h. The percent recovery of the crystalline SNPs by the combined modification of the debranching and the annealing treatment with an extended annealing incubation prepared from TK11 and TCSG2 was significantly increased to 25.7 and 23.8%, respectively. The modified starches from TK11 had better percent recovery of the crystalline SNPs than those from TCSG2. They exhibited a higher weight-average molecular weight (Mw) and a broader/bimodal molecular weight distribution with a higher polydispersity (PDI) (Mw = 92.76-92.69 kDa; PDI = 4.4) than those from TCSG2 (Mw = 7.13-7.15 kDa; PDI = 1.7). Compared to the native counterparts, the color analyses showed that the modified starches from TK11 and TCSG2 exhibited decreased brightness (L*)/whiteness index (WI) values with marked color difference values (∆E) ranging between 6.32 and 9.39 and 10.67 and 11.32, respectively, presumably due to the protein corona formed on the surface of SNPs which induced the browning reaction during the treatments. The pasting properties revealed that the modified starches displayed restricted swelling power with extremely low pasting viscosities, reflecting that they were highly thermally stable. The modified starches, especially those treated with an extended annealing incubation, exhibited marked decreases in the rate and extent of digestion and estimated glycemic index due to the honeycomb-like agglomerates comprising an assembly of densely packed SNPs. The results could provide helpful information for the preparation and characterization of the crystalline SNPs for potential applications such as emulsion stabilizers for Pickering emulsion and health-promoting ingredients.

Digestion kinetics and molecular structural evolution during in vitro digestion of green banana (cv. Giant Cavendish) starch nanoparticles.

Knowledge of digestion mechanism of starch nanoparticles are crucial for their utilization and potential applications. In this study, molecular structural evolution and digestion kinetics of starch nanoparticles from green banana (GBSNPs) during digestion (0-180 min) was investigated. Distinctive topographic changes of the GBSNPs during digestion with decreased particle size and increased surface roughness were detected. The GBSNPs showed markedly decreased average molecular weight and polydispersity in the initial digestion phase (0-20 min), and these two structural characteristics remained nearly unchanged thereafter. The GBSNPs exhibited a B-type polymorph throughout digestion, while their crystallinity decreased with increasing digestion duration. The infrared spectra revealed that the initial digestion phase led to the increased absorbance ratios 1047/1022 and 1047/1035 cm-1, reflecting the markedly increased short-range molecular order that was substantiated by the blue-shifting of COH-bending band. Logarithm of slope analysis of digestogram revealed that the GBSNPs were digested by a two-phase process that reflected the surface barrier effect exerted by the increased short-range order. The short-range molecular order strengthening induced from the initial digestion phase was responsible for the increased enzymatic resistance. The results can help to elucidate the gastrointestinal fate of starch nanoparticles for their potential applications as health-promoting ingredients.

Functional, Thermal and Structural Properties of Green Banana Flour (cv. Giant Cavendish) by De-astringency, Enzymatic and Hydrothermal Treatments.

Green banana fruit with high resistant starch (RS) content has a potential to be a nutraceutical ingredient despite having an unpleasant astringency taste and is yet to be fully explored. In this study, the green banana after de-astringency treatment was employed for flour production, and the resulting flour was subjected to modification by the combined treatments of pullulanase debranching and annealing. The banana flour (BF) and the modified flour (MF) were compared with each other by evaluating their functional, thermal and structural properties. The BF showed a restricted-swelling pasting profile, behaving like a slightly chemically cross-linked starch; the MF exhibited less pronounced changes in pasting behavior with increased solubility and decreased swelling power and dispersed volume fraction at elevated temperatures. As compared with the BF, an enhanced thermal stability of the MF was observed, reflected in the endotherm shifting to higher temperatures with increased enthalpy. The BF displayed a CA-type polymorph, while the MF comprised a mixture of B- and V-type polymorphs with increased crystallinity. The MF showed an increased molecular order, reflected in an increase in short-range double helical order detected in the starch fingerprint regions of FT-IR spectra, and along with increased crystallinity, underlying its enhanced thermal stability. The modification treatment resulted in irregularly shaped flour particles with a more compact structure as revealed by morphological characters. The results of this study can provide useful information for the development of food products using the modified green banana flour with improved thermal stability and functional properties as a health-promoting ingredient.

Toxoplasma IgG expressed in a patient with Rosai-Dorfman disease.

Rosai-Dorfman Disease (RDD) is a rare benign disease characterized by sinus histiocytosis with massive lymphadenopathy. RDD can be differentiated from other types of histiocytosis by immunochemical analysis, as RDD is positive for S100. Conversely, toxoplasmosis lymphadenitis is characterized by clusters of epithelioid histiocytes in lymphoid tissue, with mixed lymphocytic and immunoblastic cell populations. The serology data could help in diagnosing toxoplasmosis lymphadenitis, as the toxoplasma IgG should be positive. Here we present the rare case of a 73-year-old woman who presented with a left parotid mass and multiple neck lymphadenopathy that initially had been diagnosed as toxoplasmosis lymphadenitis from a positive result on serology examination, but was finally proven to be RDD based on immunochemical results. We also discuss the relationship between RDD and toxoplasmosis in this case.

Biodegradation of crystal violet by Pseudomonas putida.

Crystal violet (CV), which has been extensively used as a biological stain and a commercial textile dye, is a recalcitrant molecule. A strain of Pseudomonas putida was isolated that effectively degraded CV: up to 80% of 60 microM CV as the sole carbon source, was degraded in liquid media within 1 week. Nine degradation products were isolated and identified. We propose that CV degradation occurs via a stepwise demethylation process to yield mono-, di-, tri-, tetra-, penta- and hexa-demethylated CV species.