Food safety problems pose a great threat to the health of consumers with the greatest burden in developing countries. Street-vended foods play a key role in providing many urban dwellers with cheap, nutritious, and accessible food, but when prepared in an unhygienic and unregulated environment, they could contribute to increased food safety burden. The study investigated the microbiological recovery of work surfaces and chicken sold in Korogocho and Kariobangi North slums in Nairobi County as well as evaluating vendors’ hygiene and food safety practices. This is a cross-sectional study on an exhaustive sample size of 15 vendors, and swabs of the equipment and work surfaces and chicken were taken for microbial analysis. An exhaustive sample size of 15 vendors was selected for the study. The results showed that most vendors operate under unhygienic conditions. Microbial results revealed that raw portions of chicken had the highest contamination with all the four tested microorganisms (p<0.05). The level of E. coli ranged from 6.42±1.64 to 2.22±1.88; Salmonella spp., 6.42±1.64 to 2.22±1.88; Staphylococcus aureus, 6.92±1.32 to 2.86±1.61; and Campylobacter jejuni, 8.95±0.94 to 4.66±2.67 log CFU/g in raw and cooked chicken samples, respectively. The predictors of E. coli contamination were the presence of pests and flies, unclean vending place, vending environment littered with waste, washing of hands by the vendor, and lack of appropriate clothing among the vendors at R2 of 0.33. The vendor practices and environmental hygiene of the vending place would not significantly (p>0.05) predict contamination with Campylobacter and Staphylococcus. Consequently, there is a need to regulate the informal food processing and marketing channels, besides trainings, infrastructural development, and code of practice and inspections which are recommended in order to enhance the quality and safety standards of street-vended chicken products.

The effect of ultrasound factors (time, power, and duty cycle) on sweet potato pectin molecular weight, neutral sugar composition, pectin structure, and antioxidant activity was investigated. Sweet potato pectin dispersions (0.0025, 0.005 and 0.01g/mL) in deionized water were sonolyzed for 5, 10 and 20min to assess effect of sonication time and pectin concentration on sonolysis. For further experiments 0.0025g/mL was sonicated under varying ultrasonic power and duty cycle levels, subsequently the molecular weight, galacturonic acid content, degree of methoxylation and antioxidant activity of sonicated pectin products were investigated. Results showed that ultrasound treatment reduced pectin molecular weight, while polydispersity did not show clear trend which characterized random pectin scission, increasing duty cycle from 20% to 80% resulted in approximately threefold reduction in pectin molecular weight, increased sonication power from 100W to 400W led to significant increase in galacturonic acid content from 72.0±1.2% in native pectin to between 85.0±3.2% and 92.0±2.7%, the degree of methoxylation significantly reduced from 12.0±3.0% to between 5.25% and 6.28%, sonication led to increase in galactose and decrease in rhamnose consistent with debranching of pectin. Moreover, sonication lead to increased antioxidant capacity, both 200W and 400W sonicated pectin having higher ORAC and FRAP values, with highest pectin concentration 4mg/mL in ORAC and 0.8mg/ml in FRAP giving substantially high antioxidant activity than native and 100W treated pectin. The ORAC value of 400W sonicated pectin increased five hold above the native pectin, while it's FRAP value was almost three fold higher than native pectin. However, ultrasound did not alter pectin primary structure as showed by FTIR and HPAEC results. The results indicated that ultrasound offers effective and green process for pectin transformation and creation of antioxidant potent pectin products.

This review is a survey on ultrasonic application in selected carbohydrate polymers based upon available research reports. It covers a brief discussion on the fundamentals of ultrasound technology, before delving on the effects of ultrasound on specific polymers; pectin, chitin, starch, carrageenan and guar gum, their modification products and possible applications in food, pharmaceutical, biomedical and packaging sectors. Sonication generally leads to depolymerization and side chain break within molecules resulting into oligosugars. Oligosugars are widely used as prebiotics and specific delivery systems; moreover, nano sized products of sonication can be applied in diverse fields. Presently, ultrasonic is finding application in wider sectors therefore better understanding of the complex physico-chemical changes and mechanism of the action of high-intensity ultrasound and its effect on techno-functional properties of compounds would immensely fortify the application of ultrasonic technology.