Occurrence of antibiotic residues in milk: a case study of Gweru 2014.

Nyoka, Ruth — Wed, 01 Jan 2014 00:00:00 GMT

Title: Occurrence of antibiotic residues in milk: a case study of Gweru 2014. Authors: Nyoka, Ruth Abstract: The aim of the research was to determine the occurrence of antibiotic residues in milk in Gweru. The population consisted of twenty-eight farmers. Ten farmers were randomly selected from the population. The average volume that the farmers supply to dairy processing companies was twenty thousand liters during the time of sampling. Raw milk was sampled in two hundred and fifty mls sterile sample bottles. The samples were frozen up to the time of analysis. Detection and quantitation of antibiotic residues was done using High Performance Liquid Chromatography coupled to a mass spectroscopy detector (HPLC-MS). Fourteen antibiotics were analyzed for and these are: the sulphonamides,(trimethoprin, sulfaquinoxali, sulfamethoxin, sulfamethoxazole, sulfamethizole, sulfamethazine and sulfachloropyril), the steroids dexamethasone, the flouroquinolones which is enrofloxacin , the β-Lactams which is Penicillin G and amoxicillin as well as the Benzimidazoles which are thiabendazole and albendazole. Only one antibiotic which is albendazole was detectable on the two analyses which were done separately on the qualitative HPLC-MS machine in all the samples. The quantities of the albendazole were then quantified on the Quantitative HPLC-MS machine. During the first analysis farmer A had 241.31ppb albendazole and this was above 100ppb which is the Codex maximum residual limit for albendazole. On the second analysis done farmers ,A, B, C, D, E, F had 239.8ppb, 118.34ppb, 140.63ppb, 254.13ppb, 252.57ppb and 198.62ppb respectively which were above the 100ppb Codex Standard and other farmers were below 100ppb. T-test at 95% significance level showed that there is no significant difference in antibiotic concentration among Dairy farmers that supply milk to Dairy processing companies around Gweru. The effect of albendazole on fermentation of milk was done using back fermentation with 40ml of fermented milk in 500ml of fresh milk. Albendazole was added at different concentrations which were 0, 100, 500, 750, 1000 and 2000μL. pH was measured using a pH meter and lactic acid content was determined by using freshly prepared 0.1N sodium hydroxide. Albendazole slows down the rate of fermentation as pH and percentage lactic acid content was less in the sample with 2000μl albendazole added. pH change was highest in the samples with no antibiotic added. One way ANOVA done at 99% significance level showed that the lactic acid content vary significantly with antibiotic concentration. Regression analysis showed that there is a strong positive correlation (R2= 0.967) between antibiotic concentration and percentage lactic acid.

Effects of enzyme maceration on physicochemical properties and micronutrient bioaccessibility of Strychnos cocculoides products (juice/porridge)

Nyoni, Qhubekani — Sun, 01 Jan 2017 00:00:00 GMT

Title: Effects of enzyme maceration on physicochemical properties and micronutrient bioaccessibility of Strychnos cocculoides products (juice/porridge) Authors: Nyoni, Qhubekani Abstract: Information on the nutritional content and health-promoting properties of African indigenous fruits is very limited. Although the limited available literature does point towards wealth in essential nutrients, micronutrients and antioxidants there is still a need to fill the gap to ascertain health and nutritional claims that have been passed on from previous generations. Studies on the impact of processing of the fruit pulp on physicochemical, nutritional properties, and digestibility thereof are still very scarce and fragmented. Hence, the focus of this study was to explore enzyme (pectinase) maceration as a processing option to enhance physicochemical properties, antioxidant activity, antimicrobial potential and bioaccessibility of selected micronutrients in Strychnos cocculoides (S, cocculoides) juice/pulp. In this context, enzyme maceration refers to the breakdown of pectin that occurs in fruit pulp as complex structural polysaccharides into simpler, soluble compounds by the action of a commercial mixture of pectinases. Enzyme maceration has been reported to be beneficial in improving juice yield and enhances release of bioactive compounds into resultant juice from fruit pulps. Since the juice is commonly consumed with maize-meal porridge, the S. cocculoides enriched porridge was also incorporated into the study. Physicochemical properties were assayed using standard methods, mineral analysis by ICP-OES, phenolic compound assay by the Folin Ciocalteau method, antioxidant activity by DPPH radical scavenging ability, antimicrobial activity by the disc diffusion method and bioaccessibility was assayed using the Infogest digestion protocol. Sensory evaluation was also done to gauge the acceptance of the enzyme macerated samples. The physicochemical properties of the enzyme macerated juice and enzyme porridge were more appreciable compared to their nonenzyme counterparts. The mineral content was highest in the pulp (9.12 mg/100g for iron and 2.04 mg/100g for zinc) followed by enzyme macerated juice (8.89 mg/100g for iron and 2 mg/100g for zinc). The enzyme porridge also recorded higher levels of mineral content. Vitamin C content was affected by the thermal processing used in juice extraction and porridge preparation, although the enzyme juice still contained appreciable vitamin C content (9.45 mg/100g). The total phenol content was also higher in the enzyme juice with recorded value of 3327.75 mg/100g. The same trend was observed for antioxidant and antimicrobial activities with the enzyme macerated juice recording higher results (76.4 % for DPPH radical scavenging AOA). The bioaccessibility of iron, zinc, ascorbic acid and total phenolic compounds was higher in the enzyme treated samples, with values of 28.76 %, 18.14 %, 37.89 % and 36.75 % respectively in enzyme macerated juice. The bioaccessibility of micronutrients was significantly lower (p < 0.05) in the porridge samples, clearly highlighting the effect of the food matrix in determining bioaccessibility. The enzyme macerated samples had higher acceptance on sensory evaluation. The observed results in this study are mostly attributable to the breakdown of the complex polysaccharide, pectin, into simpler more volatile compounds such as galacturonic acid. From the observed results it can be concluded that enzyme macerated S. cocculoides juice is an excellent source of some bioaccessible micronutrients and phenolic compounds; hence its consumption should be encouraged especially in nutrition-related intervention programmes. However further research is still needed to identify individual specific phenolic compounds in S. cocculoides juice and how they are affected by enzyme maceration and in-vitro digestion. The work done in this study can also be employed for other indigenous fruits to promote their utilisation and increase their value.

MSUIR Collection:

Occurrence of antibiotic residues in milk: a case study of Gweru 2014.

Effects of enzyme maceration on physicochemical properties and micronutrient bioaccessibility of Strychnos cocculoides products (juice/porridge)