Hui-Huang Chen

In situ modification of bacterial cellulose network structure by adding interfering substances during fermentation

In an attempt to obtain bacterial cellulose (BC) with improved rehydration ability, Tween 80, urea, fluorescent brightener, hydroxypropylmethyl cellulose (HPMC) and carboxymethyl cellulose (CMC) were introduced into BC fermentation medium. Measurements of the mechanical strength of the resulting BCs (TBC, UBC, FBC, HBC and CBC) showed a decline except for UBC. SEM images showed that, although the cellulose bundle widths of FBC, HBC and CBC increase, the cellulose network void in FBC grew, while those in HBC and CBC shrank. X-ray diffraction and FT-IR analysis demonstrated that the addition of HPMC and CMC reduced the degree of crystallinity in their corresponding MBCs from 70.54% to 52.23% and 45.38%, respectively. HBC and CBC also exhibited the highest rehydration ability among all MBCs as well as the lowest crystallinity. The in situ modification with HPMC and CMC during fermentation can effectively improve rehydration ability of BC by altering its network structure.

Thermal gelation behaviors of surimi protein mixed with Hydroxypropylmethylcellulose

This study examined the thermal galation characteristics of myofibrillar protein (MP) and salt-ground horse mackerel surimi that had been mixed with hydroxypropylmethylcellulose (HPMC). Analysis, using thermal scanning rigidity monitor and differential scanning calorimetry, demonstrated that thermal gelation begins in the thermo-reversible HPMC gel used in this study at approximately 60°C. In the rescanning test, first scanning diagrams showed similar pattern, but second scanning diagrams were rather diverse between MP and MP/HPMC mixture. The addition of HPMC increased rigidity of salt-ground surimi and modified the thermal gelation during the heating process, suggesting that certain enhancing effect of gelation occurred when the mixture of MP and HPMC was heated. In the annealing test, the addition of HPMC lowered the breaking force, but increased the gel strength of surimi due to a substantial increase in deformation. Although the strong cross-linking between the two components might not occur during the gelling process, HPMC gel formed at high temperature occupies some space in thermal gel by interacting with proteins and resulted in a combinative gel with a higher rigidity and gel strength at higher temperature.

Changes in purine content of tilapia surimi products during processing

Changes in purine-related compounds of tilapia surimi product during processing were investigated. The washing step could, result in about 60% decrease of total purine content in tilapia mince during processing. The main released purine substance was inosine monophosphate. The major reducing effect was conducted in the first 10 min during washing. No significant changes were observed after washing for 20 and 30 min. The lowest total purine content of tilapia surimi product was obtained with repeating the washing step twice. Thus, this procedure could reduce the purine content of tilapia mince from a high purine content level to a middle level. The gel strength of tilapia surimi product increased with increasing washing duration within 30 min. However, tilapia surimi product with a middle purine content and acceptable gel strength might be produced by washing twice in 10 min during processing.

The bioactive composite film prepared from bacterial cellulose and modified by hydrolyzed gelatin peptide

The hydrolyzed gelatin peptides, obtained from the hydrolysis of Tilapia nilotica skin gelatin with alcalase and pronase E, were fractionated using an ultrafiltration system into hydrolyzed gelatin peptides-a (10 kDa membrane), hydrolyzed gelatin peptides-b1, and hydrolyzed gelatin peptides-b2 (5 kDa membrane) fractions. The highest oxygen radical absorbance capacity was observed in hydrolyzed gelatin peptides-b2, which contained more nonpolar amino acids than the other hydrolyzed gelatin peptides. Hydrolyzed gelatin peptides-b2 at a concentration of 12.5 mg/ml exhibited the highest proliferation ability and increased the expression of Type I procollagen mRNA, which indicated an enhanced collagen synthesis. Hydrolyzed gelatin peptides protected Detroit 551 cells from 2,2′-azobis(2-amidinopropane) dihydrochloride-induced oxidative damage and increased cell viability. Hydroxylpropylmethyl cellulose-modified bacterial cellulose and dried fabricated biofilm were less eligible for Detroit 551 cell proliferation than bacterial cellulose. The release of hydrolyzed gelatin peptides in bacterial cellulose film was slower than that in hydroxylpropylmethyl cellulose-modified bacterial cellulose and dried fabricated biofilm; thus, bacterial cellulose film and hydroxylpropylmethyl cellulose-modified bacterial cellulose and dried fabricated biofilm are suitable candidates for applications in delayed release type and rapid release type biofilms, respectively.

Preparation of Thermally Stable Microcapsules with a Chitosan–Silica Hybrid

Addition of microcapsules with a high dielectric constant and low specific heat capacity to a battered layer was designed to create a higher temperature in the crust than in the prefried fish nuggets to prevent the water vapor in the fish nuggets from migrating to the crust during microwave heating. Therefore, chitosan-silica hybrids and soybean oil were utilized to prepare the shell and core of the thermally stable microcapsules (MC(CS)), respectively. The MC(CS) were prepared by sol-gel coacervation from an oil-in-water emulsion. The sodium silicate was hydrolyzed and coacervated through polymerization for 24 h at pH 5. The zeta potential analysis indicated that chitosan with a positive charge and silica with a negative charge interacted through electrostatic attraction to form a hybrid shell. The volume mean particle size and encapsulation efficiency of the MC(CS) were 9.6 ± 0.2 μm and 75.6% ± 1.3%, respectively, when oil/chitosan = 0.2 and chitosan/silica = 0.5 (w/w). In addition to H-bonding and electrostatic attraction, Si-O-N bonds were formed between chitosan and silica. Dehydration of the bound water in the MC(CS) was observed in the range of 25 to 250 °C in the differential scanning calorimetry thermal analysis, with the lack of apparent thermal peaks indicating its high thermal stability. The decrease of force to cut the crust observed by texture analysis as well as the increase of hedonic score by consumer acceptance test revealed the addition of 1% MC(CS) significantly improved the crispness of the crust in the microwave-reheated nuggets.

Hurdle Effect of Antimicrobial Activity Achieved by Time Differential Releasing of Nisin and Chitosan Hydrolysates from Bacterial Cellulose.

We investigated the combined antimicrobial effect of nisin and chitosan hydrolysates (CHs) by regulating the antimicrobial reaction order of substances due to differential releasing rate from hydroxypropylmethylcellulose-modified bacterial cellulose (HBC). The minimum inhibitory concentration of nisin against Staphylococcus aureus and that of CHs against Escherichia coli were 6 IU and 200 μg/mL, respectively. Hurdle and additive effects in antimicrobial tests were observed when nisin was used 6 h before CH treatment against S. aureus; similar effects were observed when CH was used before nisin treatment against E. coli. Simultaneously combined treatment of nisin and CHs exhibited the low antimicrobial effect. HBC was then selected as the carrier for the controlled release of nisin and CHs. A 90% inhibition in the growth of S. aureus and E. coli was achieved when 30 IU-nisin-containing HBC and 62.5 μg/mL-CH-containing HBC were used simultaneously. The controlled release of nisin and CHs by using HBC minimized the interaction between nisin and CHs as well as increased the number of microbial targets.

The Effectiveness of a Popular Science Promotion Program on Nanotechnology for Elementary School Students in I-Lan City.

Background: Nanotechnology education has become an urgent priority to nurture skilled human resources for the rapidly developing nanotechnology-related industries. The promotion of popular science education focusing on nanotechnology is an ideal approach to bridge the gaps in formal curricula, and to stimulate curiosity about and interest in nanotechnology among schoolchildren. Purpose: The objective of this study was to evaluate the effectiveness of the Nanotechnology-based Popular Science Education Promotion and Teaching (NPSEPT) program through camp activity that was implemented in elementary schools in I-Lan City, Taiwan. Program description: To create a competitive advantage, a human resources development program was implemented as one of the nanotechnology incubation projects in Taiwan and focused on developing an appropriately-skilled professional workforce as well as promoting popular science education. Sample: The volunteer research participants were 323 sixth grade students in four elementary schools in I-Lan City, Taiwan, who were evaluated at the beginning and the end of the nanotechnology-based popular science promotion camp activity. Design and methods: A research tool called the ‘NPSEPT test’ was designed specifically for this study and was approved by experts who evaluated its content and face validity. The questionnaire was divided into three aspects: ‘Nanophenomena in the natural world’; ‘Nanomaterials and their scaling effects’; and ‘Definition, characteristics, and applications of nanotechnology.’ The effectiveness of learning among the students was analyzed using descriptive statistics, a paired sample t-test, analysis of variance (ANOVA) and a post hoc comparison. Results: The results of the three-part ‘NPSEPT test’ revealed that NPSEPT significantly advanced nanotechnology learning performance and outcomes among students in the four participating elementary schools. Of the 15 questions included in the NPSEPT test, positive change for more than 30% of students was achieved for eight questions related to nanotechnology concepts. Conclusions: Significant effectiveness of the NPSEPT program and nanotechnology learning outcomes of the elementary school students were observed. The NPSEPT program should therefore be considered an appropriate program to promote popular science with a focus on nanotechnology in elementary schools.

Changes in Purine Related Compounds of Milkfish Surimi Based Product during Processing

Changes in purine related compounds of milkfish surimi based product during processing were investigated. The objective samples were collected at the processing steps as mince (after chopping), after washing, surimi and surimi based product, separately, and subjected to purine content determination. The results indicated that washing step could result in about 60% decrease of purine substances of milkfish during processing. The main released purine substances were inosine monophosphate (IMP) and inosine. The major reducing effect was observed in the first 10min during 30min washing. No further change was found after washing for 20 or 30min. However, the gel strength of milkfish surimi based product increased with increasing washing time. The total purine content in milkfish surimi based product decreased as the washing times increased. The best gel strength was obtained for washing twice. These data suggested that the total purine content of milkfish could be reduced from high purine content level (＞100 mg/100g) to middle purine content level (25-100 mg/100g) during processing of milkfish surimi based product by washing twice for 10min in each time. The gel strength of this milkfish surimi based product was still good acceptable.