THE VENEZUELAN SALT-FISH INDUSTRIES 



In the cases of seven media, those containing dextrose, fructose, sucrose, maltose, 

 dextrin, mannitol, or d-sorbitol, the pH values of the inoculated tubes fell significantly 

 (0.9 to 1.3 units) below the values of the sterile tubes, during the first 3 days of incuba- 

 tion. During the next 5 days, the pH values of the seeded dextrose, sucrose, dextrin, and 

 mannitol cultures continued to fall slightly faster than the values of the corresponding 

 controls, the differences between the two sets reaching 1.0 to 1.5 pH units. In the cases 

 of fructose and maltose the additional incubation produced almost equal lowering of the pH 

 values in both the seeded and unseeded tubes. However, with the d-sorbitol medium the trend 

 was reversed. D'oring the 5 additional days the pH increased in the inoculated tube and fell 

 in the control. Where at the end of 3 days of incubatiop the pH of the seeded medium had 

 been 1.08 units below that of the control, at the end of 8 days the difference was only 0.30 

 units. 



The six inoculated tubes that contained l-arabinose, d-xylose, d-galactose, lactose, 

 dulcitol, or salicin showed, after 8 days of incubation, pH values that were 0.5 to 1.3 

 units higher than in similarly treated controls. However , in the cases of d-xylose, lactose, 

 dulcitol, and salicin no significant differences were apparent from the measurements that 

 had been made after the first 3 days of incubation. 



No significant differences between the pH values of the sterile and inoculated tubes 

 were observed in the case of the raffinose medium. 



Table 3 - pH Changes Caused by the Reddening Organism 1 n Various Organic Media i^ 



Carbon 



Compounds 



Tested 



1-Arabinose, C.P. 

 d-Xylose, C.P. 

 Dextrose, U.S.P, 

 Fructose, C.P, 

 d-Galactose, C.P. 

 Sucrose, C.P. 

 Maltose, C.P. 

 Lactose, Bacto 

 Raffinose, C.P. 

 Dextrin 

 Mannitol, pure 

 Dulcitol, C.P. 

 d-Sorbitol, C.P. 

 Salicin. H. P. 



3 Days Incubation 



pH Determinations After 



Inoculated 



Control 



8 Days Incubation 



Inoculated 



Control 



7.50 

 7.22 

 6.12 

 6.22 

 7.06 

 6.22 

 6.15 

 7.37 

 7.12 

 6.04 

 6.25 

 7.44 

 6.20 

 7.12 



7.03 

 7.01 

 7.03 

 7.17 

 7.12 

 7.18 

 7.27 

 7.27 

 7.25 

 7.32 

 7.25 

 7.25 

 7.28 

 7.36 



1 /Media consisted of nutrient broth, 5? sajt, and from 0.5 

 compound. A loopful from 24-hour agar slant culture was 

 out at 42°C. 



8.20 

 7.60 

 5.73 

 5.76 

 7.55 

 5.83 

 5.65 

 7.46 

 7.16 

 5.53 

 5.85 

 7.75 

 6.53 

 7.33 



6.86 

 6.85 

 6.96 

 6.76 

 7.05 

 7.03 

 6.73 

 6.90 

 7.20 

 7.06 

 7.20 

 6.96 

 6.83 

 6.86 



to 0.6^ of the indicated test 

 added, and incubation carried 



CHEMICAL CONTROL OF REDDENING ORGANISM 



Most investigators have found that sufficient heat will kill the reddening bacteria. 

 For example, Harrison and Kennedy (1922) recommended that solar sea-salt be sterilized by 

 dry heat at 100° C for 30 minutes in a kiln. Petrova (1935) suggested 120° C for the same 

 time. This method, however, has the great disadvantage that the sterile product may very 

 easily be recontaminated from infected floors, equipment, or storage rooms. 



For this reason tests were made of various chemical agents to determine whether one 

 could be found that would inhibit the growth from the time the fish was preserved to the 

 time it was desalted by the consamer. Some salteries have found that the addition of sodium 

 benzoate or boric acid to the salt is of limited value in retarding the growth of the red- 

 dening organisms, but in spite of the wide-soread use of these agents, many thousnads of 

 dollars worth of salted fish have been lost each year (Stuart, 1940b). 



Harvey (1943) found that 0.3 to .0.7 percent of a mixture of benzoic acid with an e4ual 

 weight of sodium or magnesium benzoate would inhibit mold growth in kippered fish without 



72 



