Assessment of Functional Properties of Wheat-Cassava Composite Flour.

Cassava flour (CF) was used as a raw material to replace wheat flour (WF) at levels of 0% (control), 10%, 20%, 30%, 40%, and 50% to prepare wheat-cassava composite flour (W-CF) and dough. The effects of different CF substituting levels on the functional properties of the W-CF and dough were investigated. The results show that an increase in CF led to a decrease in the moisture, protein, fat, and b* values of W-CF. The crude fiber, ash, starch, L*, a* values, iodine blue value (IBV), and swelling power (SP) of the composite flour increased gradually. It was found that the water absorption, hardness, and chewiness of the W-CF dough increased with an increase in the CF substitution level. A different trend could be observed with the springiness and cohesiveness of the W-CF dough. The resistance to extension, extensibility, and the extended area of the W-CF dough at all substitution levels was significantly lower than that of the WF dough. The elasticity and cohesiveness of the dough tended to increase for CF content from 10% to 30%, followed by a decrease at a higher replacement. Pearson correlation analysis indicated that the substitution levels of CF had a significant influence on the proximate analysis and functional properties of the W-CF and dough. This study will provide important information on choosing CF substitution levels for different products.

Effects of composition, thermal, and theological properties of rice raw material on rice noodle quality.

The study aims to evaluate the relationships between characteristics of regional rice raw material and resulting quality of rice noodles. Four of most commonly used rice cultivars in Guangxi for noodles production were investigated. The results showed that compositions of rice flour primarily affected gelatinization and retrogradation, which then influenced the textural and sensory properties of rice noodles. Amylose content had strong positive correlation with peak viscosity (PV) and trough viscosity (TV) of rice flour (P < 0.01). PV and TV had strong negative correlations with adhesive strength (P < 0.01) and positive correlations with chewiness (P < 0.05), hardness, peak load and deformation at peak of rice noodles (P < 0.01). Protein content had positive correlation with the Setback of rice flour (P < 0.05), which is known to have influences on retrogradation. In addition, solubility had positive correlations with cooking loss (P < 0.01) and broken rate (P < 0.05) of rice noodles and strong negative correlation with its springiness (P < 0.01). Swelling power had negative correlation with broken rate (P < 0.05). As sensory score of rice noodles was negatively correlated with broken rate (P < 0.05) and cooking loss (P < 0.01) and positively correlated with springiness (P < 0.01), solubility and swelling power of rice flours were presumed to be useful for predicting consumer acceptability of rice noodles.

Impacts of Environmental Factors on Pasting Properties of Cassava Flour Mediated by Its Macronutrients.

The impacts of environmental conditions on pasting and physicochemical properties were investigated using flour samples of the same cassava cultivar grown in seven different locations. Significant location differences in essential component (except for fiber) content of cassava flour were observed. Cassava flour showed obviously separated traits in the principal component analysis (PCA) of near-infrared spectra (NIR) according to geographical origins. The environmental effects were significant in the pasting properties of cassava flours. Sufficient precipitation and suitable low temperature promoted accumulation of starch in cassava, resulting in the high peak viscosity values of cassava flour. Pasting temperatures of cassava flour had a significant direct correlation with growth temperature and were negatively correlated with altitude. Precipitation from August to October showed a stronger direct correlation with trough and final viscosity. The results of this study indicated the possibility of predicting and controlling cassava flour quality and pasting properties according to the environmental conditions.

Relationships Between Cell Structure Alterations and Berry Abscission in Table Grapes.

The aim of this study was to explore the relationships between structure alterations and postharvest berry abscission in "Muscat Kyoho" "Kyoho" and "Nanyu" table grapes stored for 0, 3, or 6 days at room temperature. Microstructure analysis showed that a large number of the stalk-berry junction cells of "Muscat Kyoho" and "Kyoho" were lignified and suberized at 0 day, whereas these events seldom occurred in "Nanyu."Furthermore, the berry brush cells of the three varieties, especially those of "Nanyu," were small and dense. At 3 days, the numbers of lignified and suberized cells of "Muscat Kyoho" and "Kyoho" were reduced, and the cells had degraded, ruptured, and disappeared by 6 days. The berry brush cells of "Muscat Kyoho" and "Kyoho" were larger and more loosely arranged than were those of "Nanyu." Ultrastructure analysis showed that the cells increased in size from small to large and became loosely arranged; the smallest changes were observed in "Nanyu." The cells of "Muscat Kyoho" and "Kyoho" were hydrolyzed, liquated, and covered by granular substances at 6 days, and these features were especially prominent in "Muscat Kyoho." The detachment force of grapes declined steadily (p < 0.05) and was accompanied by an increase in berry abscission. "Nanyu" maintained the highest detachment force and the lowest berry abscission during storage (p < 0.05), followed by "Kyoho" and "Muscat Kyoho." Structural alterations were directly related to berry abscission and correlated inversely with detachment force, with the greatest alterations occurring in "Muscat Kyoho," followed by "Kyoho" and then "Nanyu."

Impacts of guar and xanthan gums on pasting and gel properties of high-amylose corn starches.

The effects of adding guar and xanthan gums on the pasting and gel properties of high-amylose corn starches, Hylon V (~50% amylose content) and NF-CG170 (~71% amylose content), were studied with waxy corn starch as a control, using an ultra-high temperature heating process (up to 130 °C) to gelatinize starches. Interaction between dispersed amylose and hydrocolloids contributed to the earlier onset of viscosity increase during pasting process (lower pasting temperatures) and strong synergistic effects in the peak, setback, and final viscosities with high-amylose starches, phenomena that were more pronounced when amylose content was higher. Conversely, addition of guar and xanthan gums to waxy corn starch resulted in higher pasting temperatures. After held at 5 °C for 2 h, the gelatinized high-amylose starch/hydrocolloid formed stronger and more elastic gels (higher G' and tanδ) with denser microstructure and thicker gel skeleton, compared to starch alone. Compared to xanthan gum, guar gum displayed a much stronger synergistic effect with Hylon V in gel strength, while their difference in synergistic effect was less pronounced with NF-CG170, indicating that amylose dominated gel properties when at a high content (i.e., ~ 71% in starch).

Cloning and molecular characterization of phospholipase D (PLD) delta gene from longan (Dimocarpus longan Lour.).

Longan (Dimocarpus longan Lour.) is a non-climacteric fruit with a short postharvest life. The regulation of phospholipase D (PLD) activity closely relates to postharvest browning and senescence of longan fruit. In this study, a novel cDNA clone of longan PLDδ (LgPLDδ) was obtained and registered in GenBank (accession No. JF791814). The deduced amino acid sequence possessed all of the three typical domains of plant PLDs, a C2 domain and two catalytic HxKxxxxD motifs. The tertiary structure of LgPLDδ was further predicted. The western blot result showed that the LgPLDδ protein was specifically recognized by PLDδ antibody. The Q-RT-PCR (real-time quantitative PCR) result showed that the level of LgPLDδ mRNA expression was higher in senescent tissues than in developing tissues, which was also high in postharvest fruit. The western-blotting result further certified the different expression of LgPLDδ. These results provided a scientific basis for further investigating the mechanism of postharvest longan fruit adapting to environmental stress.

Ultrastructural, physiological and proteomic analysis of Nostoc flagelliforme in response to dehydration and rehydration.

Nostoc flagelliforme must undergo a dehydration/rehydration cycle during its growth stages; the mechanisms underlying this constraint are examined. The novel insights into N. flagelliforme's response to desiccation and rehydration at ultrastructural, physiological and proteomic levels were offered. The structure of colonies and cells remained unchanged in response to dehydration and rehydration treatments except that the sheath appeared shrunken, and both the quantity and volume of vacuoles were decreased when dehydrated compared with rehydration. A significant increase in photosynthesis, respiration, total Rubisco activity, superoxide anion level, SOD, CAT, POD, nitrogenase and glutamine synthetase (GS) activities in response to rehydration was noted, whereas H(2)O(2), ammonium, proline and glutamate contents all registered a decrease. 32 differentially expressed proteins between dehydrated and rehydrated colonies were categorized according to their predicted functions into secretion, signaling, transcription and translation, antioxidative processes, nitrogen metabolism, energy metabolism, lipid metabolism and chaperonin. The dehydration is a quiescent state in which metabolism is down-regulated, upon rehydration, a metabolic shift occurs from quiescent to active. The specific metabolic and regulated mechanisms to accommodate the dehydration/rehydration cycle in N. flagelliforme is reported here.

Floral reversion mechanism in longan (Dimocarpus longan Lour.) revealed by proteomic and anatomic analyses.

Two-dimensional gel electrophoresis (2-DE) was used to analyze the proteins related to floral reversion in Dimocarpus longan Lour. Proteins were extracted from buds undergoing the normal process of flowering and from those undergoing floral reversion in three developing stages in D. longan. Differentially expressed proteins were identified from the gels after 2-DE analysis, which were confirmed using matrix-assisted laser desorption/ionization-time of flying-mass spectroscopy and protein database search. A total of 39 proteins, including 18 up-regulated and 21 down-regulated proteins, were classified into different categories, such as energy and substance metabolism, protein translation, secondary metabolism, phytohormone, cytoskeleton structure, regulation, and stress tolerance. Among these, the largest functional class was associated with primary metabolism. Down-regulated proteins were involved in photosynthesis, transcription, and translation, whereas up-regulated proteins were involved in respiration. Decreased flavonoid synthesis and up-regulated GA20ox might be involved in the floral reversion process. Up-regulated 14-3-3 proteins played a role in the regulation of floral reversion in D. longan by responding to abiotic stress. Observations via transmission electron microscopy revealed the ultrastructure changes in shedding buds undergoing floral reversion. Overall, the results provided insights into the molecular basis for the floral reversion mechanism in D. longan.