Utilization of small broken riceberry flour in gluten-free bread.

The aim of this study was to develop gluten-free bread formulations based on small broken riceberry flour, by using different ratios of rice flour and xanthan gum. Small broken riceberry and rice flour could be classified as low in amylose content (15.70 g and 20.50 g/100 g dry matter for small broken riceberry and rice flour, respectively). Additionally, small broken riceberry flour contained a total phenolic and total anthocyanin content approximately 500 times higher than that of rice flour. The addition of increased amounts of small broken riceberry flour and xanthan gum resulted in darker coloured gluten-free bread. However, there was no significant difference regarding moisture and specific volume. The increase of small broken riceberry flour and xanthan gum also led to a significant increase in the firmness of bread crumbs. The sensory evaluation showed differences in flavour, texture and overall liking, since adding small broken riceberry flour tended to make gluten-free bread more favourable. Bread containing rice flour and small broken riceberry flour in the ratio of 30:70 and 1.0% xanthan gum was selected on the basis of the sensory quality. Moreover, such bread also contained high levels of total phenolic and anthocyanin content.

Chitosan and chitooligosaccharides from shrimp shell waste: characterization, antimicrobial and shelf life extension in bread.

Chitosan and chitooligosaccharides were extracted from white-leg shrimp shells by chemical treatment. Low molecular weight (13 kDa) and a high degree of deacetylation (54.83%) in chitooligosaccharides led to high water solubility compared to chitosan. Antimicrobial assays indicated that chitosan and chitooligosaccharides exhibited marked inhibitory activity against food-borne pathogenics, spoilage bacterial, and fungal strains tested. However, chitooligosaccharides revealed greater inhibitory effects than chitosan on tested microorganisms. The substitution of flour by chitosan or chitooligosaccharides in bread formulation (1 g/100 g total weight basis) showed antimicrobial effects against Bacillus cereus and Rhizopus sp. growth. Also, the fruity odor in bread containing chitosan or chitooligosaccharides was delayed. Interestingly, the bread containing chitooligosaccharides showed a stronger inhibitory effect against B. cereus and Rhizopus sp. compared to bread containing chitosan and control, where B. cereus and Rhizopus sp. were observed growing on the surface of bread after 4 days of incubation at 30 °C.

Chitin synthesis by Chlorella cells infected by chloroviruses: Enhancement by adopting a slow-growing virus and treatment with aphidicolin.

Chlorella viruses or chloroviruses contain a gene that encodes an enzyme that catalyzes chitin synthesis. This gene is expressed early in viral infections to produce chitin on the outside of the Chlorella cell wall. Interestingly, chitin synthesis by microalgal Chlorella cells in combination with chloroviruses represents a unique eco-friendly process for converting solar energy and CO2 into useful materials. However, during the final viral infection stage, the host cells are completely lysed, so chitin should be harvested before cells lyse. To increase chitin yields, slow-growing chlorovirus isolates were adopted and the viral replication process was modified with an inhibitor of DNA synthesis. The accumulation of chitin on the surface of Chlorella cells infected with one of nine chlorovirus isolates carrying the chitin synthase gene was compared with that of CVK2 (a standard virus)-infected cells. Chlorella cells infected with CVNF-1 (a slow-growing virus) accumulated chitin over the entire cell surface within 15 min post-infection (p.i.), and chitin continued to accumulate for up to 8 h p.i. before cells lysed. This was 2-fold longer than the chitin-accumulation period for cells infected with CVK2. The addition of aphidicolin delayed the progression of the virus replication cycle and extended the chitin-accumulation period of CVNF-1-infected cells to 12 h p.i. before cells lysed. Additionally, chitin production in the aphidicolin-treated CVNF-1-infected cells was approximately 6-fold higher than in CVK2-infected cells not treated with aphidicolin. Thus, chitin synthesis in a Chlorella-virus system may be prolonged by using slow-growing viral isolates treated with aphidicolin.

Hyaluronan synthesis in cultured tobacco cells (BY-2) expressing a chlorovirus enzyme: cytological studies.

Extraction of hyaluronan from animals or microbial fermentation has risks including contamination with pathogens and microbial toxins. In this work, tobacco cultured-cells (BY-2) were successfully transformed with a chloroviral hyaluronan synthase (cvHAS) gene to produce hyaluronan. Cytological studies revealed accumulation of HA on the cells, and also in subcellular fractions (protoplasts, miniplasts, vacuoplasts, and vacuoles). Transgenic BY-2 cells harboring a vSPO-cvHAS construct containing the vacuolar targeting signal of sporamin connected to the N-terminus of cvHAS accumulated significant amounts of HA in vacuoles. These results suggested that cvHAS successfully functions on the vacuolar membrane and synthesizes/transports HA into vacuoles. Efficient synthesis of HA using this system provides a new method for practical production of HA.

Prolonged synthesis of hyaluronan by Chlorella cells infected with chloroviruses.

Hyaluronan (HA) synthesis by microalgal Chlorella cells in combination with chloroviruses represents a unique eco-friendly process for converting solar energy and CO2 into useful materials. However, at the final stage of viral infection, infected host cells are completely lysed, and thus HA should be harvested before cell lysis. In the current study, two methods were investigated to improve the yield of HA: (i) adopting slow-growing chlorovirus isolates and (ii) modification of the virus replication process using an inhibitor of DNA synthesis, aphidicolin. Compared with Paramecium bursaria Chlorella virus type 1 (PBCV-1), the prototype chlorovirus, slow-growing virus isolates (CVO1 and CVTS1) produced a 1.5 times higher concentration of HA in infected Chlorella cultures. Furthermore, addition of aphidicolin, an inhibitor of DNA synthesis, delayed virus replication and increased the final concentration of HA 1.5-fold that of cultures without the addition of aphidicolin. Therefore, a 2- to 3-fold increase in the yield of HA by the Chlorella-virus system was attained by using slow-growing viral isolates and the addition of aphidicolin.