Bacterial and Fungal Counts of Dried and Semi-Dried Foods Collected from Dhaka, Bangladesh, and Their Reduction Methods

Abstract

Food is a basic necessity for human survival, but it is still the vehicle for the transmission of food borne disease. Various studies have examined the roles of spices, herbs, nuts, and semidried fruits, making the need for safe and convenient methods of decontamination a necessity. The current study determined the bacterial and fungal loads of 26 spices and herbs, 5 nuts, 10 semi-dried fruits and 5 other foods. Spices, herbs and semi-dried foods demonstrated the highest bacterial and fungal loads with the majority showing over 10 4 CFU/mL. Nuts and other foods showed growths ranging from 10 2 to 10 6 CFU/mL. The current study also attempted to determine the effects of heat and plasma treatment. The log reduction of bacterial growth after heat treatment maximum: 120 min for 60 was between 0.08 to 4.47, and the log reduction after plasma treatment maximum: 40 min ranged from 2.37 to 5.75. Spices showed the lowest rates of reduction, whereas the semi-dried and other foods showed moderate to high levels of decrease after heat treatment. The log reduction of fungal growth after heat treatment ranged from 0.27 to 4.40, and log reduction after plasma treatment ranged from 2.15 to 5.91 Furthermore, we validated the sterilization effect of plasma treatment against Bacillus spp. and Staphylococcus spp. by using scanning electron microscopy. Both treatment methods could prove to be advantageous in the agriculture related fields, enhancing the quality of the foods.Key words Bacterial counts of food / Fungal counts of food / Heat treatment on food / Low-pressure plasma treatment / Scanning electron microscopic study.

Microbial Assessment of Selected, Locally- Fermented and Ready-to-eat Cassava Products Sold in Lokoja, Nigeria

“…However, it is important that food security should not be seen only in the perspective of availability either quantitatively or qualitatively. Therefore, microbiological safety of foods should also be given important consideration in order to protect the health of the people as the microbial-contaminated foods could serve as vehicle for the transmission of food borne diseases [1,2]. Food may be available but the source from which it is produced and / or processed may be unhygienic and even the chemicals that may be used to preserve it may cause serious health hazard [1].…”

Emerging Technologies for Food Safety: High Pressure Processing (HPP) and Cold Plasma Technology (CPT) for Decontamination of Foods

“…Plasma is defined as ionized gas consisting of photons, ions, radicals and free electrons in combination with excited s at a neutral charge 22 . Cold Plasma Treatment (CPT) is a method which relies on the discharge of plasma coupled with a combination of gas, ions, electrons and radicals; all working together to inactivate the organisms 9,51 .There are two types of plasma; non-thermal plasma (NTP), which functions at lower pressure and thermal plasma, which functions at higher pressure 6 . These methods were mostly limited to medical equipment sterilization, only recently gaining interest in food decontamination 9 .…”

“…Cold Plasma Treatment (CPT) is a method which relies on the discharge of plasma coupled with a combination of gas, ions, electrons and radicals; all working together to inactivate the organisms 9,51 .There are two types of plasma; non-thermal plasma (NTP), which functions at lower pressure and thermal plasma, which functions at higher pressure 6 . These methods were mostly limited to medical equipment sterilization, only recently gaining interest in food decontamination 9 . In addition to that, there is no need for use of chemicals or high temperature, minimising or removing any associated adverse effects on the food treated 22 .CPT relies on cold plasma, making it effective on bacteria, bacterial endospores, molds and yeasts 19 .Plasma can interact with the biological material allowing it to work against a variety of organisms including spores and viruses, without damaging the host, in this case the food itself 6 .…”

“…Sources of contamination of food include soil, feces, water, fungicides and insecticides, dust, insects, wild and domestic animals and handling during processing 3,5 . The continuous constant changes in the characteristics and behaviour of microorganisms, the food production processes, polluted environment, ecology and trade have resulted in new challenges to maintain food safety, coupled with consumer demands for safer foods 6 .Since there are every possibilities of bacterial and fungal contamination of foods, research necessary to find out appropriate methods of removing or reducing the microbiological loads 2,7,8,9 .…”

“…Several studies have assessed conventional, newer techniques and combinations of several methods (hurdle techniques) to control the growth of microbes in foods. Heat control measures are frequently practised, to maintain food safety; theseinclude boiling, cooking, pasteurization, autoclave and heat sterilization 9,10 . Due to the adverse effects heat treatments may incur undesirable changes in foods, such as changes in nutritionalvalues, developing burning flavour, and unpleasant taste, studies have attempted to identify non-thermal alternatives 11,12 .…”