Conventional and Non-conventional Smoking on Microbial Quality and Histamine of Ikan Fufu (Smoked Fish)

Fish is a commodity with high nutritional value. The content of this nutritional value causes fish to be easy to decompose. Therefore, it is necessary to develop and process skipjack fufu (smoked skipjack) fish that improve the quality of smoked skipjack tuna (smoked skipjack) chemically, microbiologically, and with low histamine content. The purpose of this study was to determine the chemical, microbiological, and histamine quality of smoked fish with conventional and non-conventional smoking. This type of research was a quantitative study with a randomized block design. This research is a laboratory experiment with two treatments, namely conventional and non-conventional methods equipped with three replications and three blocks. The results of the test on the third day (H3) and the ninth day (H9) of storage showed that there was no growth of Salmonella sp. and Vibrio cholera in smoked fish samples with conventional (P2) and non-conventional (P1) smoking techniques. There were differences in non-conventional and conventional smoking on the histamine content in smoked fish. Conclusion. There was no growth of Salmonella sp and Vibrio cholera in smoked fish. There is a difference in the histamine content of conventional (P2) and non-conventional (P1) smoking techniques in smoked fish.

The effect of pH on bacterial growth and histamine formation by Klebsiella pneumoniae CK02 and Raoultella ornithinolytica TN01

The present work describes the effect of pH on the growth rate and histamine formation by Klebsiella pneumoniae CK02 and Raoultella ornithinolytica TN01. Bacteria were inoculated on Tuna Fish Infusion Broth media with pH 5, 6, 7, 8 at 30°C for 6 hours. Sampling was conducted at 0, 3, and 6 hours to observe the bacteria number and calculate the histamine content formed in the medium. The number of bacteria was calculated using the Total Plate Count method, and the histamine content was analyzed using Thin Layer Chromatography with a combination of ImageJ software. Growth data and incubation time were plotted in the DMFit program to obtain growth rates. The effect of pH on growth rate and histamine formation was analyzed by ANOVA test and Duncan Multiple Range Test. The results revealed that pH affects the growth rate and histamine formation of K. pneumoniae CK02 and R. ornithinolytica TN01. The optimal growth rate of K. pneumoniae CK02 was in the range of 6-8 (0.304-0.380 log CFU/h), with the highest histamine formation ability at pH 7 (824 ppm). R. ornithinolytica TN01 had an optimal growth rate at pH 6-7 (0.480-0.508 log CFU/ml), with optimal ability to produce histamine at pH 6-8 (620-1,077.5 ppm). At pH 5, the growth rate and the ability of histamine formation by K. pneumoniae CK02 and R. ornithinolytica TN01 were inhibited.

Low-Histamine Diets: Is the Exclusion of Foods Justified by Their Histamine Content?

A low-histamine diet is currently the most advised strategy to prevent the symptomatology of histamine intolerance. Conceptually, these diets should be founded on the exclusion of histamine-containing foods, although a certain disparity is found within the list of excluded foods in accordance with the different low-histamine diets available in the literature. This study aimed to critically review low-histamine diets reported in the scientific literature, according to the histamine and other biogenic amine contents of the excluded foods. A total of ten scientific studies that provided specific recommendations on the foods that must be avoided within the framework of a low-histamine diet were found. Overall, the comparative review brought out the great heterogenicity in the type of foods that are advised against for histamine intolerant individuals. Excluded foods were, in most cases, different depending on the considered diet. Only fermented foods were unanimously excluded. The exclusion of 32% of foods could be explained by the occurrence of high contents of histamine. The presence of putrescine, which may interfere with histamine degradation by the DAO enzyme at the intestinal level, could partly explain the reason why certain foods (i.e., citrus fruits and bananas) were also frequently reported in low-histamine diets. Finally, there was a range of excluded foods with an absence or very low levels of biogenic amines. In this case, certain foods have been tagged as histamine-liberators, although the mechanism responsible has not yet been elucidated.

Effect of Brine Concentrations on the Bacteriological and Chemical Quality and Histamine Content of Brined and Dried Milkfish

In this research, the occurrence of hygienic quality and histamine in commercial brined and dried milkfish products, and the effects of brine concentrations on the quality of brined and dried milkfish, were studied. Brined and dried milkfish products (n = 20) collected from four retail stores in Taiwan were tested to investigate their histamine-related quality. Among them, five tested samples (25%, 5/20) had histamine contents of more than 5 mg/100 g, the United States Food and Drug Administration guidelines for scombroid fish, while two (10%, 2/20) contained 69 and 301 mg/100 g of histamine, exceeding the 50 mg/100 g potential hazard level. In addition, the effects of brine concentrations (0%, 3%, 6%, 9%, and 15%) on the chemical and bacteriological quality of brined and dried milkfish during sun-drying were evaluated. The results showed that the aerobic plate count (APC), coliform, water activity, total volatile basic nitrogen (TVBN), and histamine content values of the brined and dried milkfish samples decreased with increased brine concentrations, whereas those of salt content and thiobarbituric acid (TBA) increased with increasing brine concentrations. The milkfish samples prepared with 6% NaCl brine had better quality with respect to lower APC, TVBN, TBA, and histamine levels.

Isolation and Screening of Histamine-Producing Bacteria from the First Six Months of the Cat Hai Fish Sauce Fermentation Process

Histamine is considered to be a hazard in fish sauce, and histamine poisoning usually causes symptoms such as a runny nose, asthma (bronchospasm), urticaria, rash, itching, swelling (eyelids, puffy lips), inflammation, and redness of the conjunctiva. In this study, Cat Hai fish sauce, one of the major traditional fish sauce manufacturers in Vietnam, was used to investigate the variation in histamine content during the fermentation process and to isolate histamine-producing bacteria. Six Dich Chuop samples corresponding to the first sixth months from the beginning of fermentation were collected for these purposes. The results showed that the content of histamine in the six samples corresponding to the first six months from the beginning of fermentation tended to increase during fermentation, reaching the highest rate of 604.85 ppm in the fifth month. A total of 50 isolates were collected from TSA medium and used for screening histamine-producing bacteria on HBI medium. Among these bacteria, four isolates (CH2.4, CH3.3, CH4.4, and CH5.1) were capable of producing histamine, and the highest producing isolate, CH5.1 (from 5th month), was identified as Tetragenococus halophilus. Furthermore, this Tetragenococus halophilus was determined to have the highest histamine production in HBE supplemented with 1% histidine at 50°C, pH 6.0, and 25% NaCl.