Journal of Food Safety and Hygiene
Volume:7 Issue: 4, Autumn 2021

Ultrasonic methods are increasingly being used in the food industry for both food analysis and food modification. Ultrasound technology is relatively inexpensive, simple and cost-effective in terms of energy and time and is a non-destructive technique compared to other conventional technologies. The ultrasonic spectrum based on frequency and intensity is divided into two types, including low frequency (less than 100 kHz)-high-power (more than 1 W/cm2) ultrasound and high frequency (more than100 kHz) low-power (less than 1 W/cm2) ultrasound. The effect of ultrasound on various materials is caused by the formation, growth, and collapse of bubbles, which is referred to as cavitation. The ultrasonic spectrum based on frequency and intensity is divided into two types, including low frequency (less than 100 kHz)-high-power (more than 1 W/cm2) ultrasound and high frequency (more than 100 kHz) low-power (less than 1 W/cm2) ultrasound. Ultrasound applications in the food industry are very diverse. This review summarizes the major popular applications of low and high-power ultrasound in food science and technology.

Selenium is an essential trace element that is crucial for normal functioning of human body systems and it is obtained from diet or dietary supplements. The concentration of selenium (Se) varies from soil-to-soil and therefore in various food types. We profiled the selenium concentration in the major African fresh foods and studied the effect of boiling, frying and overnight soaking on their selenium content. The foods were taken to the chemistry laboratory, processed for determining selenium concentration in the fresh foods and then subjected to the various treatments before determining their Se concentration using an atomic absorption spectrometer. Among the fresh foods studied, pumpkin seeds were found to have the highest Se concentration (109.25 ± 0.125 parts per billion (ppb)), while Irish potatoes had the lowest (16.25 ± 0.125 ppb). In most fresh foods studied, boiling and frying had the effect of reducing the Se concentration, except in yams that showed an increased concentration after frying. Overnight soaking of matooke (plantain bananas) and beans showed an effect of causing a considerable reduction in the Se concentration from 36.375 ± 0.281 ppb and 59.125 ± 0.031 ppb to 14.03 ± 0.441 ppb and 24.375 ± 0.281 ppb, respectively. Boiling and frying cause a significant reduction in Se concentration of most African fresh foods. Overnight soaking of matooke and beans caused further reduction in the selenium concentration of the fresh foods. This implies that people who pre-soak their food before cooking it are likely to lose more selenium than those who do not soak and may be more likely to suffer from Se deficiencies.

Lignocellulosic biomers have been found to possess great potential as substrates for various bioconversion processes; this is due to their vast availability coupled with their renewable nature. The direct conversion of lignocellulosic substrates is however hindered by their rigid and complex structural composition, which must be broken down via a process called pretreatment. This research aimed at comparing the effects of different methods used in pretreating lignocellulose. Samples of the selected biomers were subjected to various methods of pretreatments (mechanical, chemical, physicochemical and a combination method). Compositional analysis of each biomer was carried out before and after each pretreatment method, the pretreated biomers were then subjected to microbial hydrolysis using Trichoderma viride and Aspergillus niger for 5 days, after which estimation of reducing sugar present was carried out. Analytical contents of the samples showed high cellulose, hemicellulose and lignin contents (36.39, 26.52, 13.62 and 43.30, 32.30, 6.42% respectively). The combination of 2 or more methods proved more efficient than other individual methods, significantly increasing cellulose contents from 36.39% to 58.61% and 43.30% to 61.09% in wheat straw and corn stover respectively, while eliminating the lignin barrier from 13.62% to 3.82% and 6.42% to 2.38% respectively. The reducing sugar results proved that Trichoderma viride had the most sugar content of 0.55 g/g in corn stover after pretreatment with the combination method, making it more effective in cellulose hydrolysis.

Food-borne diseases are caused by a wide range of microbiological and chemical or toxins with different levels of severity, which range from mild sickness to life-threatening illness. The World Health Organization estimates that the global burden of foodborne diseases is 420000 mortality and at least 1 in 10 people falls ill every year from eating contaminated food. African and South-East Asia Regions have the highest burden of foodborne diseases. Several devastating outbreaks of foodborne diseases have been reported in Bhutan. This report presents the food safety surveillance data for food samples collected between June 2019 to December 2021 from five Districts (Paro, Thimphu, Phuentsholing, Gelephu and Monggar). Ready-to-eat food samples were collected by Food inspectors and samples were shipped to Royal Centre for Disease Control (RCDC) maintaining a cold chain during transportation. The results show that 12.36% (n=78) of food samples were nonacceptable due to indicator test organism contamination and 8.71% (n=55) of the RTE food samples were unacceptable due to the presence of the pathogenic organism. The common type of pathogen isolated was Staphylococcus aureus, and Bacillus cereus, and low detection of Aeromonas and Shigella spp. The seasonality pattern of food contamination shows that most contamination occurred higher during hot and wet seasons. The findings demonstrate that RTE is likely to cause foodborne illness. Therefore, education on personal hygiene, good manufacturing practices and food safety aspect would improve food quality thereby reducing the incidence of foodborne incidences.

High intake of total fructose, total glucose and benzoic acid can cause many adverse health effects. Most commercially available fruit juice and nectar brands in Sri Lanka are not claimed on the label about the levels of fructose, glucose and benzoic acid in the products. Available brands of fruit juices [Mixed Fruit Juice (MFJ) and Mango Juice (MJ)] and fruit nectars [Mixed Fruit Nectar (MFN) and Mango Nectar (MN)] were selected through a pre-validated questionnaire. Seven brands of MN and MFN were identified as mostly consumed and there was a significant difference (p<0.05) in the total fructose and total glucose levels among the brands. Total fructose of MN and MFN was in the range of 28.54 ± 3.03 gl-1 to 60.28 ± 5.04 gl-1 and 30.46 ± 8.56 gl-1 to 62.47 ± 9.27 gl-1 respectively. Total glucose content of MN was in the range of 17.49 ± 5.39 gl-1 to 41.87 ± 2.11 gl-1 and for MFN from 29.29 ± 4.34 gl-1 to 85.71 ± 5.64 gl-1. Total fructose in MJ and MFJ was in the range of 32.28 ± 0.86 gl-1 to 37.66 ± 0.55 gl-1 and 33.14 ± 0.87 gl-1 to 36.81 ± 1.81 gl-1 respectively. Three, out of the four brands of MN and MFN contained benzoic acid. One brand of MN and one brand of MFN had exceeded the permitted level (120 mg/l) of benzoic acid. Benzoic acid was present in two, out of three brands of MJ and MFJ. It can be concluded that there is a variation in total fructose, total glucose and benzoic acid contents in fruit nectars and juices available for sale in Anuradhapura town area. However, some brands have violated the Sri Lanka food regulations.

Coated skewers are very popular in Ouagadougou. This work aims to assess the microbial quality of coated skewers sold in the streets of Ouagadougou and their isolated Staphylococcus aureus and Pseudomonas spp antimicrobial resistance. A total of 30 coated skewers samples were collected from various processors for microbial analysis using standard methods. The antimicrobial resistance test was performed using the agar plate diffusion method. The microbial load varied from 6.0×104-1.7×108 cfu/g (aerobic mesophilic bacteria (AMB)), 1.5×10-2.7×107 cfu/g (coliform), 0.0 to 6.1×101 (S. aureus) and 10-25 cfu/g (Pseudomonas spp.). Globally, 70% (21/30), 30% (09/30), 40% (12/30) and 6.67% (02/30) of the analyzed samples were unacceptable based on the load of AMB, coliform, S. aureus and Pseudomonas spp., respectively. Four coated skewers were contaminated by Pseudomonas spp. About susceptibility to antimicrobial agents, 91.67% of S. aureus strains were resistant to ceftazidime and aztreonam, while a low resistance rate was observed for the other antibiotics. Pseudomonas spp strains, were resistant to cotrimoxazol (75%) but sensitive to the other antibiotics. These results highlight poor hygienic conditions of coated skewers preparation in Ouagadougou. These practices contribute to their microbial contamination. Isolated bacteria showed a different level of resistance to the tested antibiotics. There is a need of good manufacturing practices to improve the hygienic quality of coated skewers.