Fruit juices contain a complex mixture of nutrients which are beneficial to the maintenance of good health and have intrinsic disease risk reduction properties. In addition to the major nutrients (e.g. vitamins, minerals) inherent in the fruit itself, juices also contain phytochemicals (often referred to as phytonutrients) derived from the plant. Phytochemicals are thought to act as antioxidants and antibacterial/antiviral agents. They also have the properties to stimulate the immune system and positively effect on hormones. Considering the importance of fruit juice governments throughout the world advocate the inclusion of fruit juices in a healthy diet. A juice, that is 100% derived from its parent fruit or fruits, is almost universally regarded as a healthy and nutritious part of a human diet [1] . Besides, fruit juices are delicious and have a universal appeal especially to children and young people. Although in developed countries fruit juices commonly form part of the breakfast and are produced in very large quantities, they do not form the normal diet in our country and the fruit industry is in its infancy in Bangladesh.

These useful food items can turn into a disease-causing source if contaminated with pathogens. Juices can be contaminated in any step of their production from fruit processing to juice packing. Pathogenic organisms can enter fruits and vegetables through damaged surfaces, such as punctures, wounds, cuts, and splits. This damage can occur during maturation or during harvesting and processing [2] . A pathogen that has become internalised within a fruit or vegetable must be able to survive in the product until it reaches the consumer in order to become a public health hazard. Most fruit juice is sufficiently acidic to inhibit the growth of pathogenic organisms. However, studies conducted on the internalisation, survival, or growth of microorganisms in fruits and juices have shown that a number of pathogenic organisms can be present and survive in a wide range of fruit and vegetables. Several studies have demonstrated the survival of microorganisms, including human pathogens, in various juices. E. coli O157:H7 has been found to survive in apple juice for up to 24 days at 4˚C and orange juice for 24 days at refrigeration temperatures with very little decrease in numbers [3] . Although it has been shown that pathogens can survive in orange juice, Salmonella and Listeria do not grow when the pH is below 4.4 [4] [5] .

There have been documented outbreaks of illness in humans associated with the consumption of unpasteurised fruit and vegetable juices. Pathogens responsible for these outbreaks include Salmonella and verotoxin producing E. coli [6] [7] . Unpasteurised fresh orange juice contaminated with Salmonella was linked to an outbreak in a Florida Theme Park, USA. More than 60 visitors were affected [8] . In Australia, 427 confirmed cases of salmonellosis were reported in 1999 after the consumption of unpasteurised orange juice [9] . A total of 48 cases of E. coli O157 were reported after drinking unpasteurised apple juice in Washington DC in 1996 [10] . L. monocytogenes has also been identified as a pathogen that is of concern in relation to these products as the bacteria are present on the surfaces of raw fruits and vegetables [11] .

Although a lot of criteria are involved to standardize the quality of fruit juices, and even sometimes question arises about the ingredients of juices—whether they are really fruit juices or only mixture of chemicals, our aim was to analyse the microbial quality of collected processed fruit juices from different retailers.

Figures 1(a)-(d) show the microbiological status of the studied fruit juice samples. The TVBC, TSC, TCC and TFC ranged from 3.5 × 10⁴ cfu/ml to 1.8 × 10³ cfu/ml, 2.1 × 10³ cfu/ml to 1.3 × 10² cfu/ml, 1.7 × 10² cfu/ml to 1.0 × 10² cfu/ml and 2.0 × 10² cfu/ml to 1.2 × 10² cfu/ml, respectively, in JP juices ( Figure 1(a) ); 4.9 × 10³ cfu/ml to 2.5 × 10³ cfu/ml, 1.9 × 10³ cfu/ml to 2.0 × 10² cfu/ml, 1.9 × 10² cfu/ml to 1.0 × 10² cfu/ml and 1.3 × 10² cfu/ml to 1.0 × 10² cfu/ml, respectively, in JM juices ( Figure 1(b) ); 3.2 × 10⁴ cfu/ml to 3.1 × 10³ cfu/ml, 2.5 × 10³ cfu/ml to 1.8 × 10² cfu/ml, 1.8 × 10² cfu/ml to 1.2 × 10² cfu/ml and 1.8 × 10² cfu/ml to 1.0 × 10² cfu/ml, respectively, in JA juices ( Figure 1(c) ); and finally, 3.3 × 10³ cfu/ml to 2.0 × 10³ cfu/ml, 1.3 × 10³ cfu/ml to 3.8 × 10² cfu/ml, 1.7 × 10² cfu/ml to 1.0 × 10² cfu/ml and 1.2 × 10² cfu/ml to 0.5 × 10² cfu/ml, respectively, in JS juices ( Figure 1(d) ). Variability in microbial counts among different juice samples can be attributed to differences in processing hygiene, storage conditions, raw material quality, and potential post-processing contamination [24] - [26] . TFCC and TAC were found nil in all fruit juice samples.

A total of 46 bacteria were isolated from sixteen fruit juice samples among which 10 (21.74%) were Staphylococcus aureus, 8 (17.39%) were Escherichia coli, 4 (8.70%) were Bacillus cereus, 6 (13.04%) were Micrococcus luteus, 4 (8.70%) were Streptococcus lactis, 4 (8.70%) were Alcaligenes faecalis, 4 (8.70%) were Enterobacter aerogenes, 3 (6.52%) isolates were Acinetobacter colcoaceticos, and 3 (6.52%) were Lactobacillus fermentum ( Figure 2 ). The presence of B. cereus, S. aureus and E. coli in juice samples were considered alarming since some strains of these bacterial species can cause bacterial food poisoning [27] .

On the other hand, a total of 10 fungal species were isolated from different juice samples among which 4 (40%) isolates were Aspergillus niger, 4 (40%) isolates were Penicillium spp., 2 (20%) isolates were Fusarium spp. ( Figure 3 ). Presence of these fungal isolates were also considered hazardous since some species of fungus are involved in the spoilage of food which may be injurious for health [28] .

Table 1 shows the microbiological status of the studied fruit juices on the basis of ICMSF (1978) [19] and the ready-to-eat microbiological guidelines set by Food Standards Australia New Zealand (FSANZ, 1996) [20] . The classification of samples as “unsatisfactory” or “moderately satisfactory” was based on numerical cutoffs defined by ICMSF and FSANZ, which set limits on microbial counts in ready-to-eat foods [19] [20] .

Note: S = Satisfactory, M = Moderately satisfactory and US = Unsatisfactory.

Among the juices one JP and one JS was unsatisfactory and the rest of the samples were moderately satisfactory. Although none of the juices were found to be potentially hazardous, the local fruit juice industries should take more care for maintaining the microbiological quality since not even a single sample could achieve the overall satisfaction level. The presence of coliform and staphylococcus mainly affected the overall assessment which indicates the probable contamination from water and air respectively. Although coliform count and fecal coliform count were satisfactory or moderately satisfactory for all samples, presence of E. coli in the samples was of great concern. In this study, only 8 (17.39%) isolates were E. coli. Since their pathogenicity was not studied, it implies a certain risk, as some serotypes of E. coli may cause diarrhea in infants, and their presence in large number may lead to diarrhea in adults [29] [30] . Further testing for the pathogenicity of the isolated E. coli strains is recommended. The same recommendation also implies to the isolated fungal strains.

Considering the presence of contaminants in the studied juice samples, it could be clearly interpreted that any preservation method should be implemented by the juice manufacturing companies before marketing their products. Since they are demanding that they are not using any preservative at least proper pasteurization can be an option for their choice. Radiation could be an alternative preservation method. Ionizing radiation has recently been widely applied in low dose (<10 kGy) level for both short term and long-term preservation of food. According to FAO, IAEA, and WHO expert committee, dose up to 10 kGy level of radiation can be safely applied for preservation of food without any nutritional or toxicological problems [31] [32] . From Figure 4 and Figure 5 it was evident that irradiation has effect on microorganisms associated with fruit juices. The effect of radiation on the isolated microorganisms indicated that a dose of 7 kGy was effective in eliminating S. aureus and M. luteus. E. coli, E. aerogenes and L. fermentum were completely eliminated at 3 kGy, 2 kGy, and 1 kGy, respectively. A radiation dose of 9 kGy was effective in eliminating S. lactis, A. faecalis, and A. colcoaceticos. The spore-forming B. cereus survived even at 10 kGy of gamma radiation. At a gamma radiation dose of 3 kGy, A. niger, Penicillium spp., and Fusarium spp. were completely eliminated.

Among the identified bacteria, Bacillus cereus exhibited high resistance to gamma radiation due to its spore-forming nature, unlike Staphylococcus aureus, which lacks such protective structures [33] . B. cereus spores can survive even at 10 kGy, whereas non-spore-forming bacteria are eradicated at lower doses. In this study, at 10 kGy radiation dose, B. cereus count reduced from 2.3 × 10⁸ cfu/ml to1.5 × 10¹ cfu/ml (i.e. 7 log reductions). Dymsga et al. [34] reported that a low dose of irradiation immediately reduces total bacteria from 10⁵ to 10³ cfu/ml in food sample, which is supported by the present findings. Stavin et al. [35] also reported that an irradiation dose of 1.0 to 3.0 kGy effectively reduces of bacterial load in food. Rashid et al. reported that bacterial counts of frozen fish samples were reduced from 10⁶ to 10⁴ cfu/ml at a 4.0 kGy irradiation dose [36] .

From the radiation sensitivity study of isolated bacteria and fungi in the present investigation, it was observed that, except for the spore-forming bacterium B. cereus, all microorganisms were eradicated at a 10 kGy radiation dose. Therefore, a 10 kGy gamma radiation dose can be used to preserve juices if they are free from spore forming bacteria. This approach can save the consumers from ingesting harmful chemical preservatives or juices with reduced nutritional value due to extensive heat treatment. The effect of irradiation on the nutritional content,

sensory properties (such as taste, texture, etc.), and shelf life of the juices were not analysed in this study. However, previous studies have indicated that gamma irradiation at doses up to 10 kGy does not significantly alter the nutritional quality of foods [37] [38] . Future studies should focus on evaluating these aspects to ensure consumer acceptability.