April - June 2007 - Kasetsart University

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368 hansenii were similar to that of naturally fermented Nham (Figure 1). This microbial group rapidly increased after casing and reached the values of about 10 9 CFU/g in all the sausages, even in the samples to which starter cultures were not added. These high values remained relatively constant during ripening. Due to relatively high microbial load in Nham raw mix(10 7 CFU/g), inoculation of starter cultures at levels of 10 4 and 10 6 CFU/g had no significant effects on the LAB counts during fermentation. Similar to the results of Khieokhachee et al. (1997), initial flora of the Nham derived mainly from the raw materials. The number of LAB increased drastically to a maximum of 10 9 CFU/g within 18 h and remained the same until the fermentation was completed at 24 h for all batches . Thus, fermentation of Nham involving successive growth of different groups of microorganisms was dominated by LAB. Various metabolic products of LAB, such as shortchain organic acids, carbon dioxide, hydrogen peroxide, diacetyl, and bacteriocin, are known as antimicrobial agents (Rowan et al., 1998). Accumulation of organic acids also resulted in a decrease of pH. Thus, the dominance of LAB is <strong>Kasetsart</strong> J. (Nat. Sci.) 41(2) likely to contribute to the inhibition of other microorganisms. The addition of L. sakei and D. hansenii as starters might prevent the development of flora LAB that were present naturally in the initial mixture, and L. sakei might be able to dominate the whole ripening period in the batches while the control predominated with LAB flora. Biogenic amines determination Tyramine and cadaverine were present exclusively in 24 h fermented samples in typical quantitative sequence: cadaverine content was more than tyramine content (Table 1), other amines were not detectable. Both biogenic amines increased after 24 h of ripening until the final ripening of 120 h. The differences between Nham elaborated with and without starter culture were observed, and the control Nham had significantly higher values of cadaverine and tyramine than the Nham inoculated with starter cultures. The L. sakei had significantly lower concentrations of biogenic amines than L. sakei and D. hansenii. Cadaverine and tyramine in fermented sausages were produced Table 1 Biogenic amine contents (mg/kg) in Nham. Time (h) Control L. sakei L. sakei and D. hansenii CAD TYR CAD TYR CAD TYR 0 ND ND ND ND ND ND 24 135.47 74.28 174.54 57.28 197.41 67.91 ± 14.85 aA ± 5.71 aB ± 18.22 aC ± 7.96 aD ± 16.34 aF ± 7.14 aG 48 197.32 95.72 204.69 68.46 201.36 94.85 ± 18.92 bA ± 8.42 bB ± 23.85 bA ± 4.85 bC ± 14.89 aA ± 5.54 bB 72 216.41 97.61 225.87 75.37 223.52 96.47 ± 21.56 cA ± 7.48 bB ± 19.51 cC ± 6.29 bcD ± 26.25 bAC ± 8.20 bB 96 218.82 102.32 218.34 77.16 227.28 104.62 ± 24.63 cA ±12.85 bB ± 25.18 cA ± 7.28 cC ± 21.94 bA ± 7.87 bcB 120 235.95 138.59 224.74 82.23 232.86 107.58 ± 17.44 dA ± 14.74 cB ± 21.82 cC ± 5.45 dD ± 25.17 cA ± 6.41 cE Mean values and standard deviations with different letters (a, b, c) in the same column indicate significant differences (P
y lysine- and tyrosine-decarboxylase activities, of Enterobacteriaceae, respectively. So, L. sakei and D. hansenii in Nham might inhibit the growth of Enterobacteriaceae resulting in decrease the lysine- and tyrosine-decarboxylase activity and biogenic formation (Bover-Cid et al., 2001b). The main factors seemed to be a suitable starter culture and good quality raw materials (Bover-Cid et al., 2001a). However, in the present study, the high quality raw materials used were not effective in preventing the production of cadaverine and tyramine in control Nham (Table 1), and low contents of these amines were obtained only when a starter culture was included in sausage formulation. In conclusion, to avoid the presence of high concentrations of biogenic amines in Nham, it was advisable to use a competitive starter culture such as L. sakei, a negative-decarboxylase strain, which might be predominant throughout the process, thus it would prevent the growth of bacteria which could produce biogenic amines. Low occurrence of biogenic amines in raw pork meat: usually tyramine did not exceed a few mg kg -1 (tyramine less than 3.5 mg kg -1 as observed by Hernandez-Jover et al., 1997) while ripened and cured meat showed a general increase of amines (Bover-Cid et al., 1999). The choice of starters could be useful tool to control and reduce the development of some Enterobacteriaceae strains. However, the presence of biogenic amines in ripened dry uncooked fermented meat was fundamentally a consequence of the activity of decarboxylase-positive strains of Lactobacillaceae and Enterococcaceae. Biogenic amines content depended also on an equilibrium between the decarboxylating and amine oxidizing activity of microflora (Gardini et al., 2002). Therefore, to obtain Nham with low amine concentrations besides the high quality raw materials and good manufacturing practices, it is necessary to employ highly competitive amino <strong>Kasetsart</strong> J. (Nat. Sci.) 41(2) 369 acids decarboxylase negative starters cultures and the starter culture should be able to compete and grow well at the temperature intended for processing of the product (Maijala et al., 1995). Analysis of FAA The main differences in the content of total FAA among batches were detected at the end of the processing (5 days), where lower quantities were detected in all batches. From Table 2, after 5 days of incubation at 30°C, NC caused decrease of 36.8 % in total FAA while Nham with L. sakei and the Nham with mixed cultures of L. sakei and D. hananii caused decrease of 13.3% and 19.73%, respectively, in the concentration of FAA. The total FAA of Nham with starter culture was higher than that of the control (Table 2). This suggested that the starter cultures batches might have higher proteolytic activity than the non-inoculated control batch and /or catabolized free amino acids to be the other products such as biogenic amines less than the control due to the batches added with starters lagged of amino acid decarboxylase. Free amino acids precursors of biogenic amines were detected by HPLC. During fermentation step, the increases of tyrosine and lysine which were the precursors of tyramine and cadaverine, respectively were obsereved in all batches. However, after 5 days of ripening, the concentrations of tyrosine and lysine in Nham with starter cultures were more than that of the control, while the biogenic amines, tyramine and cadaverine in the control were more than that of the batches with starter cultures. Evaluation of FAA during the ripening of fermented Nham sausages indicated an increase in most FAA over the 0-5 day fermentation period. The main changes observed in the decrease of free amino acids at the end of processing showed a higher decrease proportion of glutamic acid and arginine in the control than that of the batch with L. sakei and the batch with
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April - June 2007 Volume 41 Number
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KASETSART JOURNAL NATURAL SCIENCE T
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Kasetsart J. (Nat. Sci.) 41 : 205 -
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harvesting time which started from
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y Chen and Paull (2000). Figure 1 a
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pineapple fruit allowed the accumul
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Kasetsart J. (Nat. Sci.) 41(2) 215
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Cluster analysis Cluster analysis u
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Table 3 (Continued) 1 2 3 4 5 6 7 8
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CONCLUSION AFLP markers classified
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difference of soil texture used in
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under wet soil condition planting.
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tropics. Following the expansion, w
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sealed in a plastic box with 1 cm w
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moisture content increment after so
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Frequency Frequency 30 20 10 0 20.0
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School, Kasetsart University. The a
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for combining ability of lines (Lam
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selective mass sibbing within indiv
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Although most of S 2-interfamily hy
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composite sets as used in this stud
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days. The numbers of calli producin
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the report of Ching (1982) showing
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clearly amplified bands generated b
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caused by either the recombination
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Kuhlmann, V. and B. Foroughi-Wehr.
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Xanthomonas fuscans subsp. aurantif
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was collected and washed with 70% e
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expected size was amplified with 35
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eaction technique has been used for
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Schaad, N.W., D. Opgenorth and P. G
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MATERIALS AND METHODS Model descrip
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calculated TF value calculated TF v
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sincere gratitude and deep apprecia
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1989). In monogastrics, the inclusi
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of all LLS samples in this study we
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Melbourne, Parkville, Victoria. Goe
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considered responsible for low prod
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mineral supplementation suggested b
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Body weight chane (kg/head) 32 30 2
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CONCLUSION AND RECOMMENDATION With
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SAS. (Statistical Analysis System).
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genes covering a variety of desirab
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mg/l NAA and 0.5 mg/l zeatin) incub
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5. Purification by various sucrose
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as the culture period increased. So
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culture, pp. 1-20. In L.C. Fowke an
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GC. Analytical methods Total carboh
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ash. The crude hot water polysaccha
Page 117 and 118: spirulan (H-SP), and a desulfated c
Page 119 and 120: Kasetsart J. (Nat. Sci.) 41 : 319 -
Page 121 and 122: cells often displayed an increased
Page 123 and 124: LITERATURE CITED Bell, T.A. and D.V
Page 125 and 126: for alternative sources of supply.
Page 127 and 128: BR2.1.2 formed the same clade with
Page 129 and 130: supplement with glutamate (Iida et
Page 131 and 132: optimal for S. limacinum BR2.1.2 fo
Page 133 and 134: fluorescent lamp at 1.5 kLux develo
Page 137 and 138: Wisconsin, USA). Total extracted RN
Page 139 and 140: RESULTS Cloning and sequencing of m
Page 141 and 142: Expression of rmIL-2 and purificati
Page 143 and 144: other strains of mice have differen
Page 145 and 146: dose interleukin-2 therapy promotes
Page 147 and 148: The chitosano-oligosaccharides are
Page 149 and 150: enzyme and cells were maximized by
Page 151 and 152: of crude chitosanases. Fortunately,
Page 153 and 154: Relative activity (%) 100 80 60 40
Page 155 and 156: Uchida, K. Tateishi, O. Shida and K
Page 157 and 158: MATERIALS AND METHODS 1. Materials
Page 159 and 160: without coating and coated with pec
Page 161 and 162: in Table 5-7. It was found that the
Page 165 and 166: the cultures at 10,200 × g for 15
Page 167: incubation and reached the final pH
Page 171 and 172: during the stages of ripening as su
Page 175 and 176: As the 25 companies were divided in
Page 177 and 178: All the data comes up with informat
Page 179 and 180: as piece “A” or straight as pie
Page 181 and 182: et al. (1998); Zeng (2000); and Tal
Page 183 and 184: p 1, i * Kasetsart J. (Nat. Sci.) 4
Page 185 and 186: c ≤ c2 jq2 j n q p k p * 2, j , ,
Page 187 and 188: algorithm would consider RM 5, prio
Page 189 and 190: Kasetsart J. (Nat. Sci.) 41(2) 389
Page 191 and 192: the maximum deviation of about 10%.
Page 193 and 194: Stock Quantities Using Heuristic Op
Page 195 and 196: which dynamically and automatically
Page 197 and 198: 2. Framework architecture and compo
Page 199 and 200: Risk (VaR) calculation which was im
Page 201 and 202: Throughput (job/sec) 7 6 5 4 3 2 1
Page 203 and 204: Speed up 40 35 30 25 20 15 10 5 0 F
Page 205 and 206: and discovery, resource selection a
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April - June 2007 - Kasetsart University

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