Tony J. Fang

Antioxidant properties of a new antioxidative peptide from algae protein waste hydrolysate in different oxidation systems

Microalgae have been a popular edible food, but there are no known reports on the antioxidative peptides derived from microalgae. The algae protein waste, which is normally discarded as animal feed, is a by-product during production of algae essence from microalgae, Chlorella vulgaris. Algae protein waste was hydrolyzed using pepsin, and a potent antioxidative peptide of VECYGPNRPQF was separated and isolated. The peptide could efficiently quench a variety of free radicals, including hydroxyl radical, superoxide radical, peroxyl radical, DPPH radical and ABTS radicals, and performed more efficiently than that observed for BHT, Trolox and peptides from marine protein sources in most cases. The purified peptide also has significant protective effects on DNA and prevents cellular damage caused by hydroxyl radicals. In addition, the peptide has gastrointestinal enzyme-resistance and no cytotoxicity observed in human lung fibroblasts cell lines (WI-38) in vitro. These results demonstrate that inexpensive algae protein waste could be a new alternative to produce antioxidative peptides.

Anticancer and Antioxidant Activities of the Peptide Fraction from Algae Protein Waste

Algae protein waste is a byproduct during production of algae essence from Chlorella vulgaris. There is no known report on the anticancer peptides derived from the microalgae protein waste. In this paper, the peptide fraction isolated from pepsin hydrolysate of algae protein waste had strong dose-dependent antiproliferation and induced a post-G1 cell cycle arrest in AGS cells; however, no cytotoxicity was observed in WI-38 lung fibroblasts cells in vitro. The peptide fraction also revealed much better antioxidant activity toward peroxyl radicals and LDL than those of Trolox. Among these peptides, a potent antiproliferative, antioxidant, and NO-production-inhibiting hendecapeptide was isolated, and its amino acid sequence was VECYGPNRPQF. These results demonstrate that inexpensive algae protein waste could be a new alternative to produce anticancer peptides.

Microbiological quality of 18 °C ready-to-eat food products sold in Taiwan

A total of 164 samples of 18 degrees C ready-to-eat (RTE) food products, purchased in 1999-2000 from convenience stores and supermarkets in central Taiwan, were examined to determine the microbiological quality of these products. The 18 degrees C RTE food products, manufactured by 16 factories, were divided into groups based on the type of food and their major ingredients. Aerobic plate count, coliforms, Escherichia coli, Bacillus cereus, Staphylococcus aureus and psychrotrophic Pseudomonas spp. were evaluated. The incidence of E. coli and coliforms in these 18 degrees C RTE food products was 7.9% and 75.0%, respectively, while 49.8% and 17.9% of the samples were found to contain B. cereus and S. aureus, respectively. Among the samples tested, 1.3% of the food products contained more than 10(5) CFU g(-1) of B. cereus and 0.7% contained more than 10(5) CFU g(-1) of S. aureus. The pH values of the samples were all below 7.0, except for cold noodles, which had pH values ranging from 5.18 to 8.20. Among the five types of 18 degrees C food products tested, the highest incidence of E. coli (16%) and Pseudomonas spp. (64.0%) were detected in hand-rolled sushi in a cone shape. On the other hand, the highest incidence rate of coliforms, B. cereus, and S. aureus were found in sandwiches (88%), cold noodles (66.7%) and rice balls rolled in seaweed (25.0%), respectively. Food products made of ham contained the highest incidence of coliforms (88.0%) and E. coli (16.0%), while food products containing meat and ham as the major ingredients had the highest incidence rates of B. cereus (62.5%) and S. aureus (26.1%), respectively. For coliforms, E. coli, B. cereus and S. aureus, the percentage of 18 degrees C RTE food products exceeding the microbiological standards for RTE food accepted by Republic of China was 75.0%, 7.9%, 49.8% and 17.9%, respectively.

Growth of Listeria monocytogenes and Pseudomonas fragi on cooked park in a modified atmosphere packaging/nisin combination system

The influence of carbon dioxide (CO2) atmospheres combined with various nisin concentrations on the growth of Listeria monocytogenes Scott A and Pseudomonas fragi CCRC 10939 on cooked tenderloin pork stored at 4 and 20°C was investigated. Atmospheres employed were 100 and 80% CO2; and an air control. Pork tenderloins were steamed, cooled, and coinoculated with L. monocytogenes and P. fragi . Headspace composition of sample bags determined throughout storage at 4°C indicated that greater growth occurred on air-stored tenderloins than on modified atmosphere-stored (MA-stored) samples. Colony counts of P. fragi were appreciably reduced by the MA storage; however, the same pattern was not found in L. monocytogenes . Although P. fragi on cooked tenderloin was unaffected by nisin, the growth of L. monocytogenes was prevented when samples were treated with 1 × 104 nisin IU/ml. In addition, the modified atmosphere packaging (MAP) (100% CO2, 80% CO2 + 20% air)/nisin (103, 104 IU/ml) combination system used in this study decreased growth of both organisms, and this inhibitory effect for MAP/nisin combination system was more pronounced at 4°C than at 20°C. The concept of a Safety Index, which compares numbers of spoilage and pathogenic organisms, was also used as a measure of the relative safety of this MAP/nisin combination system.

Improvement of astaxanthin production by Phaffia rhodozyma through mutation and optimization of culture conditions

Abstract Phaffia rhodozyma strains were treated with the mutagenic agent NTG several times and plated onto yeast-malt agar containing β-ionone as a selective medium. One of the NTG-treated strains (NCHU-FS301) produced considerably more astaxanthin than the parent CBS-6938 (strain NCHU-FS301 produced 1515.63 μg/g and CBS-6938 565.08 μg/ l ). When the kinetic parameters of the specific growth rate (μ) and specific astaxanthin productivity ( q p ) were used to judge the association between growth behavior and product formation, NCHU-FS301 was shown to be a more positive growth-associated fermentation type than the parent strain. A study of the effects of the carbon source on red pigment formation revealed that glucose could support the highest total astaxanthin production (7809.3 μ g/ l ). Yeast extract was the best nitrogen source in supporting the highest total astaxanthin formation (8637.5 μg/ l ). When mixed nitrogen sources were used, a mixture of yeast extract, beef extract, and potassium nitrate (1:1:1) supported more pigmentation (8052.6 μg/ l ) than the other mixtures tested. Astaxanthin-overproducing mutants could be useful in providing a natural source of astaxanthin for the aquacultural industry.

Growth patterns of Escherichia coli O157 : H7 in ground beef treated with nisin, chelators, organic acids and their combinations immobilized in calcium alginate gels

The effects of antimicrobial substances including nisin, acetic acid, lactic acid, potassium sorbate and chelators (disodium ethylenediamine tetraacetic acid [EDTA] and sodium hexametaphosphate [HMP]), alone or in combination and, with or without immobilization in calcium alginate gels, on the growth of Escherichia coli O157:H7 in ground beef were investigated. Results showed that acetic acid and potassium sorbate could inhibit the growth of E. coli O157:H7 effectively at 10°C and at 30°C. Both EDTA and HMP did not halt the growth of E. coli O157:H7. In an antimicrobial system immobilized with calcium alginate, most of the antimicrobials could not inhibit the growth of E. coli O157:H7 in ground beef at 10°C and at 30°C, with the exception of acetic acid and lactic acid. Immobilization did not enhance the effectiveness of acetic acid against E. coli O157:H7 in ground beef at 10°C and at 30°C (P>0.05) but it did enhance the effectiveness of lactic acid at 10°C. In a system combining different antimicrobials, treatment with nisin /EDTA or nisin/potassium sorbate at 10°C revealed a significantly lower population change of E. coli O157:H7 compared to samples treated with nisin, EDTA or potassium sorbate alone. The use of calcium alginate immobilization further enhanced the effectiveness of the combination system of nisin/EDTA, nisin/acetic acid and nisin/potassium sorbate on the growth of E. coli O157:H7 in ground beef at 10°C but it was not effective at 30°C.

Enhanced production of xylanase by Aspergillus carneus M34 in solid-state fermentation with agricultural waste using statistical approach

The production of a low molecular weight xylanase by Aspergillus carneus M34 was investigated in solid-state fermentation using agricultural waste as the substrate. Experimental designs were practiced for optimisation of the medium composition. When agricultural wastes of coba husk and corn steep liquor were used in the ratio of 4.5:0.5, a 22.5% increase of xylanase activity was observed compared with the medium containing only coba husk. The incubation time for xylanase production can be reduced from 12 days to six days by increasing the inoculum size to 2 x 10(7) sporesmL(-1). The optimal media compositions were as follows by using statistical approach: coba husk/corn steep liquor (4.5/0.5); NH(4)NO(3), 32.4 gL(-1); CaCl(2), 1.34 gL(-1); MnSO(4).7H(2)O, 0.0124 gL(-1). Xylanase activity of 1721 Ug(-1) substrate was obtained by A. carneus M34 in a six-day period at 30 degrees C, which was a 227% increase compared with that obtained before applying the Plackett-Burman and response surface methodology experimental design.

Extractability of astaxanthin in a mixed culture of a carotenoid over-producing mutant of Xanthophyllomyces dendrorhous and Bacillus circulans in two-stage batch fermentation

The productivity and extractability of astaxanthin in a mixed culture of Xanthophyllomyces dendrorhous (formerly Phaffia rhodozyma) NCHU-FS501, an astaxanthin over-producing mutant, and Bacillus circulans CCRC 11590 was evaluated in a 1.5 l fermentor using a two-stage batch fermentation technique. The first stage was for X. dendrorhous cultivation. The second stage was the mixed fermentation of the red yeast and B. circulans. The highest lytic enzyme activity of B. circulans was found at 24 h with yeast nitrogen base (YNB) as the nitrogen source and incubation at 30 °C in a pure culture. The induction of B. circulans lytic enzyme activity was influenced by the cell wall concentration of X. dendrorhous. The fastest induction was observed with addition of 2.5 g/l cell wall. The cultivation time in the first stage of fermentation significantly affected the extractability of carotenoid in the second stage of fermentation. Minimum extractability was found when X. dendrorhous was cultivated for 96 h in the first stage. Glucose concentration of 45 g/l in YNB supported high X. dendrorhous growth and astaxanthin production, with astaxanthin production of 9010 g/l was observed during the first stage. Although the red yeast produced more astaxanthin with peptone as nitrogen source during the first stage, YNB supported the highest extractability of carotenoid and lytic activity of B. circulans in the second stage of fermentation. The optimal pH and temperature for pigment extraction in the mixed culture were pH 6.5 and 30–34 °C, respectively. Under these conditions, about 97% of the total pigment could be extracted after a 48 h incubation time. When the crude enzyme was recycled in the mixed culture, lytic enzyme activity of 20 units/ml was obtained after one incubation cycle (48 h), with 69% of total carotenoids extracted.

Development and validation of growth model for Yersinia enterocolitica in cooked chicken meats packaged under various atmosphere packaging and stored at different temperatures.

Mathematical models that can predict the growth of Yersinia enterocolitica in chicken meats were evaluated in this study. The growth curves for Y. enterocolitica in chicken meats variously packaged (air, vacuum, and modified atmosphere packaging [MAP]) and stored at various temperatures (4, 10, 16, 22, 28, and 34 degrees C) were constructed. The Gompertz model was applied to fit each of the experimental curves for the conditions mentioned above. The variations in the parameters, including lag time (lambda) and specific growth rate (mu), at various temperatures were then described by the following models: the variations in lag time were described by the Adair and Smith models and the variations in the specific growth rate were described by the Ratkowsky and Zwietering models. The various models were then compared using graphical and mathematical analyses such as mean square error (MSE), regression coefficient (r2), bias factor, and accuracy factor. The results indicate that the mean r values in the Gompertz model for chicken meats packaged in air, vacuum, and MAP were 0.99, 0.99, and 0.95, respectively. The lag time modeled with the Adair and Smith functions exhibited a greater variance and demonstrated larger errors. The MSEs were 0.0015 and 0.0017 for Ratkowsky and Zwietering models, respectively. The r2 values in the Ratkowsky and Zwietering models were both 0.99. The bias factor was 1.017 for the Ratkowsky model and 1.096 for the Zwietering model. The accuracy factor of the Zwietering model was 1.174, which was lower than that in the Ratkowsky model (1.275), indicating that the former model was more accurate than the latter in predicting the specific growth rate of Y. enterocolitica in chicken meats.

Food safety control system in Taiwan: the example of food service sector

Abstract The World Trade Organization’s Sanitary Phytosanitary Agreement facilitates the scrutiny of the benefits and costs of country-level regulatory programs and encourages regulatory rapprochement on food safety issues. In Taiwan, food safety control system (FSCS), which includes good hygienic practice (GHP) and hazard analysis critical control point (HACCP), has been developed to embody principles of safe food processing. From 1998 to 2001, the total number of factories that supply box meals and food service sectors that implemented HACCP was 139 and 46, respectively. Taiwan’s FSCS is fully compatible with international codes adopted by CODEX alimentarius and will play an important role in maintaining the safety of foods not only in domestic market but also in international trade. This paper illustrates the development and implementation of FSCS system for the food service sector in Taiwan, which sets a good example for the country-level regulation on food-safety system, especially for those factories that export their agricultural products.