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Effects of Fermentation Temperature and Time on the Physicochemical and Sensory Characteristics of Douchi

Chuanlai Xu*, Kai Hao, Chifang Peng, Weihui Cai and Zhengyu Jin


School of Food Science and Technology, Southern Yangtze University, Wuxi City, Jiangsu, P.R. China, 214036

Article history:

Received August 18, 2004
Accepted February 28, 2005

Key words:

fermentation of douchi, sensory characteristics

Summary:

In this paper studies were made to generate data on the physicochemical and sensory characteristics of douchi prepared by fermentation at different temperatures for variable time prior to mechanical drying. Fermentation was carried out at 20, 30 and 40 °C for 12, 24, 48 and 72 h prior to drying at 50 °C. Physiochemical and sensory characteristics were monitored. The results show that fermentation conditions of 30 °C for 24 h and 30 °C for 48 h bring about more acidic douchi with superior sensory characteristics.

 


*Corresponding author:     xcl@sytu.edu.cn
                                                      ++86 510 58 81 769

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Does Probiotic Yeast Act as Antigenotoxin?

Malda Maija Toma*, Jekabs Raipulis, Inta Kalnina and Reinis Rutkis


Institute of Microbiology and Biotechnology, University of Latvia, Kronvalda boulv. 4, LV-1586, Riga, Latvia

Article history:

Received August 31, 2004
Accepted June 28, 2005

Key words:

Saccharomyces boulardii, genotoxins, SOS chromotest, antigenotoxicity

Summary:

The effect of probiotic yeast Saccharomyces boulardii on genotoxicity induced by the well-known mutagen 4-nitroquinoline-N-oxide (4-NQO), as well as antibacterial (furazolidone) and antibiotic (nalidixic acid) drugs, has been studied using the short-term bacterial assay, SOS chromotest, with Escherichia coli PQ 37 as the test organism. It has been shown that S. boulardii possesses antigenotoxic activity, revealed by SOS chromotest, when coincubated with these genotoxins. A weaker antigenotoxic activity against the same compounds was observed with S. carlsbergensis, too.




*Corresponding author:     toma@lanet.lv
                                         ++371 703 48 87
                                         ++371 703 48 85

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Microbial Characterization of Table Olives Processed According to Spanish and Natural Styles

Daniela Campaniello, Antonio Bevilacqua, Daniela D’Amato, Maria Rosaria Corbo, Clelia Altieri and Milena Sinigaglia*


Department of Food Science, University of Foggia, Via Napoli 25, I-71100 Foggia, Italy

Article history:

Received August 30, 2004
Accepted July 28, 2005

Key words:

Bella di Cerignola, table olives, Spanish style and natural processing, microorganisms

Summary:

A study on the microflora of table olives »Bella di Cerignola«, produced according to Spanish style and natural processing, is presented. The samples (olives and brines) were taken at different fermentation phases; olives, before treatments, were analyzed too. pH was monitored and microbial populations were assessed by standard plate count. Determination of the following microbial groups was carried out: mesophilic bacteria, lactic acid bacteria, Enterobacteriaceae, Pseudomonadaceae, staphylococci, Micrococcaceae and yeasts. In the second phase, the identification of mesophilic bacteria, lactic acid bacteria and yeasts was performed. The amount of lactic acid bacteria and yeasts increased during the storage in all the samples, but no significant differences were observed between the two styles. At the end of fermentation an increase of Pseudomonadaceae cell load was observed, which was absent in the first phase of fermentation. The samples analyzed were extremely unsteady, therefore the addition of starter lactic acid bacteria could standardize olive processing. Lactobacillus plantarum, Bacillus spp. (mainly B. subtilis) and Candida spp. were the predominant species at the end of the processing.



*Corresponding author:          m.sinigaglia@unifg.it
                                               ++39 0881 589 233
                                               ++39 0881 740 211

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Molecular Methods Used for the Identification of Potentially Probiotic Lactobacillus reuteri Strains

Agnes Weiss1,2, Hans Peter Lettner3, Walter Kramer3, Helmut Karl Mayer2* and Wolfgang Kneifel1


1
Division of Food Microbiology and Hygiene, Department of Food Science and Technology, BOKU - University of Natural Resources and Applied Life Sciences Vienna, Gregor-Mendel-Strasse 33, A-1180 Vienna, Austria

2Division of Food Chemistry, Department of Food Science and Technology, BOKU - University of Natural Resources and Applied Life Sciences Vienna, Gregor-Mendel-Strasse 33, A-1180 Vienna, Austria
3Lactosan Starterkulturen GmbH & Co KG, Industriestrasse West 5, A-8605 Kapfenberg, Austria

Article history:

Received August 23, 2004
Accepted June 28, 2005

Key words:

Lactobacillus reuteri, probiotics, identification, molecular methods, PCR, RAPD-PCR, PFGE

Summary:

Forty potentially probiotic Lactobacillus strains as well as reference strains of different genera were grown under standardised conditions. Cell masses were harvested and DNA was isolated. For identification, all strains were subjected to genus-specific polymerase chain reaction (PCR), and the affiliation with the genus Lactobacillus was confirmed for all isolates. Using two species-specific primer-pairs for Lactobacillus reuteri, specific amplicons were observed for eight of the forty investigated strains. For differentiation, these eight strains as well as the reference strains of the species L. reuteri and closely related species were subjected to randomly amplified polymorphic DNA (RAPD)-PCR using fourteen arbitrary primers. Two selected strains as well as probiotic and common reference strains were further investigated applying pulsed field gel electrophoresis (PFGE). With the latter two methods, individual profiles were found for most strains, but no difference between probiotic and common strains could be made out.



*Corresponding author:           helmut.mayer@boku.ac.at
                                               ++43 (0)1 476 546 106
                                               ++43 (0)1 4789 114

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Factors Affecting the Growth and Production of Milk-Clotting Enzyme by Amylomyces rouxii in Rice Liquid Medium

Pei-Jing Yu and Cheng-Chun Chou*


Graduate Institute of Food Science and Technology, National Taiwan University, 59, Lane 144, Keelung Rd., Sec. 4, Taipei, Taiwan

Article history:

Received August 28, 2004
Accepted June 28, 2005

Key words:

Amylomyces rouxii, milk-clotting enzyme, rice liquid culture

Summary:

Amylomyces rouxii is one of the main fungi usually coexisting with yeasts in Chinese yeast ball, the starter of chiu-niang, a traditional Chinese fermented product from rice. In the present study, growth and production of milk-clotting enzyme (MCE) in gelatinous rice liquid culture of A. rouxii as influenced by waxy (gelatinous) rice content in the medium (5–20 %), temperature (25–40 °C), cultivation time (1–6 days), shaking speeds (0–150 rpm) and metal ions (Na+, K+, Zn2+, Mg2+, Mn2+, Cu2+, Ca2+, Fe3+ and Al3+) were investigated. Results revealed that rice content in the medium, shaking speed, temperature and cultivation time all affected the mycelial propagation and the production of milk-clotting enzyme by A. rouxii in the rice liquid culture. The maximum milk-clotting enzyme activity of ca. 1.22 unit/mL of medium was observed in the 3-day static culture of test organism grown at 30 °C in the medium containing 20 % of gelatinous rice, while mycelial propagation increased with the increase of cultivation time and shaking speed. Furthermore, a significant increase (p<0.05) in the milk-clotting enzyme activity of ca. 1.90 unit/mL of medium, which was about 1.55-fold of the control, was observed when Al3+ was added to the rice liquid medium.



*Corresponding author:           fstcchou@ccms.ntu.edu.tw
                                               ++886 2 33 664 111
                                               ++886 2 23 620 849

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