Abstract
This study was carried out for monitoring the bacteriological and mycological quality of Kishk. Thirty six random samples of Kishk were collected from different farmer producer and shops in Assiut city and some villages around it. All samples were subjected to microbiological examinations and mycotoxine investigation. Enterococci spp., Aerobic bacteria, Anaerobic bacteria and “Yeastsand molds” were isolated in 61.6, 100, 86.1 and 77.8 % of the examined Kishk samples, respectively, and with average total counts of 6.95 x104, 2.26 x 105, -- , and 3.9 x104, respectively. The presence of high contamination in Kishk samples reflects the poor sanitary conditions during the manufacturing stages or post production. Aspergillus flavus, Aspergillus niger and Mucor spp. were detected in 22.2, 16.7 and 8.3 % of the examined Kishk samples, respectively. Aflatoxin M1 was found in 23.53 % of the samples. The concentration of aflatoxin M1 in positive samples was 139 - 221 ng/Kg (average 149.8 ± 56.5 ng/Kg) by ELISA and 56 – 218 ng/Kg (average 135.3 ± 61.5 ng/Kg) by TLC. Kishk samples from Assiut city presented a high incidence of AFM1 at levels below the limits established by Egyptian regulations. The general human exposure to AFM1 by the consumption of contaminated kishk is probably non-significant in Egypt. However, the fact that AFM1 is a potent hepatocarcinogen warrants concern about its occurrence in kishk. A high percentage of positive samples would be considered inappropriate for human consumption, when considering the tolerance limit adopted by the European Community. It could be concluded that, the product quality is variable, with some samples showing noticeably more contamination than others. This is probably a reflection of the standards of hygienic measures applied during production and the quality of raw materials used (fermented milk and crushed dried boiled wheat grains).
Highlights
Kishk is one of the natural healthy food products, which have great taste and cultural values that are increasingly attractive to the Egyptian consumers
Isolated microorganisms (% of positive samples and total count / g) and percentage of isolated fungi in the examined Kishk samples are shown in Tables 1 and 2 respectively
The concentration of aflatoxin M1 in positive samples was 139 - 221 ng/Kg by ELISA and 56 – 218 ng/Kg by TLC. These findings revealed that the concentration of Aflatoxin M1 (AFM1) was relatively higher when estimated by ELISA than when estimated by TLC
Summary
Kishk is one of the natural healthy food products, which have great taste and cultural values that are increasingly attractive to the Egyptian consumers. The traditional method for the manufacture of Kishk is very basic (composed mainly of crushed dried boiled wheat grains and acidified milk). The microbiological quality of the product is mainly governed by factors such as: 1- the method used to ferment the milk; 2- the hygienic conditions practiced during the manufacturing stages including whether the milk was heat treated (boiled) or not before the fermentation stage; and 3- the drying stage in the open air in sunny areas (Tamime and O'Conner, 1995). The low moisture content (10 %), acidic nature of the product (pH 3.8) and the addition of salt during manufacture (2.8 g NaCI / 100 g dried product) may be the cause of microbiological safety of Kishk (Tamime et al, 1999)
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