Drought has detrimental effects on plant metabolic processes. Given the importance of maize (Zea mays L.) and soybean as food and feed crops, it is pivotal to identify genetic determinants of the responses of these plants to drought. Sterols are structural components of cell membranes and regulate the levels of reactive oxygen species (ROS). ROS accumulate to toxic levels during drought-induced plant water deficit. Sterols are synthesized by squalene epoxidases/squalene monooxygenases such as cycloartenol synthase and lanosterol synthase. The study presented here provides transcriptomic and metabolomic responses of maize and soybean in reference to sterol biosynthesis. Drought reduced the relative water content of maize and soybean leaves, increased their H2O2 content and lipid peroxidation and altered the activity of some of the major enzymes controlling the antioxidant system of maize and soybean. On the other hand, cycloartenol synthase and lanosterol synthase gene expression in leaves was altered by drought in both maize and soybean and this corresponded to changes in sterol content in plant tissue. This suggests a role of sterols in plant responses to drought.
Nanoparticles were isolated from tef and maize starch modified with added stearic acid after pasting at 90 °C for 130 min. This was followed by thermo-stable alpha-amylase hydrolysis of the paste. The resultant residues were then characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic laser scattering particle size distribution (DLPSD), atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HRTEM). XRD and DSC showed that the isolated residues consisted of amylose-lipid complexes. These complexes were type II with melting temperature above 104 °C. DLPSD, AFM and HRTEM showed that the isolated tef and maize starch residues consisted of nanoparticles which became more distinct with increased hydrolysis time. The isolated tef and maize nanoparticles had distinct particles of about 3–10 nm and 2.4–6.7 nm, respectively and the yield was about 24–30%. The results demonstrated that distinct (physically separate) nanoparticles of less than 10 nm can be isolated after formation during pasting of tef and maize starch with stearic acid. The production and isolation of the nanoparticles uses green chemistry principles and these nanoparticles can be used in food and non-food systems as nanofillers.
Peaches are popular, nutritious and widely consumed. Being a tree crop, it is considered a low risk fruit, with no direct water contact, and no previous foodborne disease outbreaks associated with its consumption. However, in 2014 the pioneer association between stone fruit and a foodborne illness was reported, linking Listeria monocytogenes to stone fruit. This highlights the need for better understanding of risk associated with contaminated fresh stone fruit, in order to implement adequate preventative measures. No information is available on the presence of foodborne pathogens on peaches in the supply chain. A case study approach was therefore followed to assess foodborne pathogen presence on the farm, focusing on the impact of irrigation water, facility sanitation and hygiene by collecting various fruit and environmental samples (n = 428). This study demonstrates the effectiveness of integrating basic microbial testing with safety management and risk assessment tools that can be collectively used to improve the food safety management system. No Salmonella Typhimurium was detected from samples, however, Escherichia coli O157:H7, Listeria spp. and Staphylococcus aureus were detected on fruit and environmental samples. Despite the GlobalG.A.P. certification status of the farm, livestock frequented water sources which lead to E. coli O157:H7 contamination. This conclusion was based on positive detection of foodborne pathogens from the water sources and subsequent removal of livestock which resulted in a definite decrease in pathogen detection. A number of E. coli O157:H7 and S. aureus were detected during the second year of monitoring from environmental samples and it was observed that the personal hygiene and facility sanitation was not adequately enforced. Based on feedback given to the farmer, enforcement was improved and a definite decrease in foodborne pathogens was observed in the following sampling cycle. Areas of risk that were still identified following the fourth year of monitoring included the water source used for irrigation and poor sanitation in the production and processing facilities. Limited foodborne pathogen prevalence on peaches over the full study period as well as the extended export supply chain at controlled temperatures resulted in low-to-medium calculated consumer risk. The correct and meticulous implementation of integrated and holistic pre- and post-harvest food safety management systems is therefore essential to prevent produce contamination, reduce the consumer risk and therefore ensure overall product safety.
Drought has detrimental effects on plant metabolic processes. Given the importance of maize (Zea mays L.) and soybean as food and feed crops, it is pivotal to identify genetic determinants of the responses of these plants to drought. Sterols are structural components of cell membranes and regulate the levels of reactive oxygen species (ROS). ROS accumulate to toxic levels during drought-induced plant water deficit. Sterols are synthesized by squalene epoxidases/squalene monooxygenases such as cycloartenol synthase and lanosterol synthase. The study presented here provides transcriptomic and metabolomic responses of maize and soybean in reference to sterol biosynthesis. Drought reduced the relative water content of maize and soybean leaves, increased their H2O2 content and lipid peroxidation and altered the activity of some of the major enzymes controlling the antioxidant system of maize and soybean. On the other hand, cycloartenol synthase and lanosterol synthase gene expression in leaves was altered by drought in both maize and soybean and this corresponded to changes in sterol content in plant tissue. This suggests a role of sterols in plant responses to drought.
The polyphenolic constituents and antioxidant activity of aqueous and acetone extracts of Vachellia karroo leaves were determined in order to evaluate its efficacy in scavenging radicals such as DPPH, ferric reducing power and nitric oxide as an antioxidant model. The flavonols and flavonoid and phenolic content of the leaf extracts were also accessed using benchmark phytochemical reaction methods. Results of the phytochemical analyses revealed the presence of flavonoids and flavonol and phenolic compounds in the leaf extracts. The total phenolic content values in the aqueous and acetone leaf extracts were 7.40 and 11.09 mg tannic acid equivalent/g of extract powder, respectively. The total flavonol and flavonoid content values of the aqueous leaf extracts were 9.90 and 53.23 mg quercetin equivalent/g of extract, respectively, while those of the acetone leaf extracts were 1.18 and 5.18 mg quercetin equivalent/g of extract, respectively. At 0.2 mg/mL, the values for the scavenging activities of the acetone and aqueous extracts of the V. karroo leaves were significantly higher (p < 0.05) than that of the ascorbic acid but comparable to BHT against ferric oxide radicals. The findings from the study reveal that the antioxidative potentials of V. karroo leaf extract and could serve as free radical inhibitors, possibly acting as principal antioxidants.
Author: Stephen Greenberg
This contribution maps the South African agro-food system with a focus on corporate ownership and power, inspired by value chain work applied to the food system as a a whole. Corporations tend to dominate some nodes, for example input supply, grain storage and handling, and feedlots. Other nodes have a corporate core but with a wide number of smaller economic actors, for example agricultural production, food manufacturing, wholesale and retail, and consumer food service. This wide number of actors points to possible areas of intervention to boost livelihoods by supporting their economic activities. The paper considers the influence of corporations in structuring consumer perceptions on food quality and health, from input into apparently neutral dietary-based guidelines to advertising. Financialisation in the food system, including the institutionalisation of share ownership and the rise of agri-investment companies, and the multi-nationalisation of South African agro-food capital especially into Africa, have implications for the ability of the nation state to regulate activities in the agro-food system. The paper concludes with some recommendations for further work.
Ferulic acid is a natural antioxidant found in various plants and serves as a precursor for various fine chemicals, including the flavouring agent vanillin. However, expensive extraction methods have limited the commercial application of ferulic acid, in particular for the enrichment of food substrates. A recombinant Aspergillus tubingensis ferulic acid esterase Type A (FAEA) was expressed in Aspergillus niger D15#26 and purified with anion-exchange chromatography (3487 U/mg, K m = 0.43 mM, K cat = 0.48/min on methyl ferulate). The 36-kDa AtFAEA protein showed maximum ferulic acid esterase activity at 50 °C and pH 6, suggesting potential application in industrial processes. A crude AtFAEA preparation extracted 26.56 and 8.86 mg/g ferulic acid from maize bran and triticale bran, respectively, and also significantly increased the levels of p-coumaric and caffeic acid from triticale bran. The cost-effective production of AtFAEA could therefore allow for the enrichment of brans generally used as food and fodder, or for the production of fine chemicals (such as ferulic and p-coumaric acid) from plant substrates. The potential for larger-scale production of AtFAEA was demonstrated with the A. niger D15[AtfaeA] strain yielding a higher enzyme activity (185.14 vs. 83.48 U/ml) and volumetric productivity (3.86 vs. 1.74 U/ml/h) in fed-batch than batch fermentation.
Background: To investigate the mediation effects of physical activity (PA) on the relationship between the perceived neighborhood aesthetic environment and overweight/obesity in free-living South Africans. Methods: A cross-sectional study of 671 adults aged ≥ 35 years was analyzed. PA was assessed using the validated International Physical Activity Questionnaire. Perceived neighborhood aesthetics was assessed using the Neighborhood Environment Walkability Scale Questionnaire. Results: Of 671 participants, 76.0% were women, 34.1% aged 45–54 years, and 69.2% were overweight or obese. In adjusted logistic regression models, overweight/obesity was significantly associated with neighborhood aesthetics [odds ratio (OR) = 0.68; 95% confidence interval (CI), 0.50–0.93] and PA (OR = 0.65; 95% CI, 0.65–0.90). In expanded multivariable models, overweight/obesity was associated with age 45–55 years (OR = 1.59; 95% CI, 1.05–2.40), female gender (OR = 6.24; 95% CI, 3.95–9.86), tertiary education (OR = 4.05; 95% CI, 1.19–13.86), and urban residence (OR = 2.46; 95% CI, 1.66–3.65). Conclusion: Aesthetics was positively associated with PA; both aesthetics and PA were negatively associated with overweight and obesity. There was no evidence to support a significant mediating effect of PA on the relationship between aesthetics and overweight/obesity. Future studies should consider objective assessment of aesthetics and PA. In addition, future studies should consider using longitudinal design to evaluate food-related environments, which are related to overweight or obesity.
Global reports on illnesses and deaths related to food consumption continue to raise concern in most countries. This has led to diligent efforts to improve the manner in which food is handled. Hygienic handling of carcasses after slaughter is critical in preventing contamination and ensuring meat safety in both formal and informal meat trading sectors. However, in the informal sector, regulations as prescribed in the Meat Safety Act No. 40 of 2000, which have been set to protect consumer health, are not always adhered to. Although these regulations are put into practice in the formal sector, meat safety challenges associated with meat handling during distribution continue to raise concern. The distribution stage is the most critical period, during which the quality of meat can easily be compromised. Furthermore, meat inspection at the abattoir covers only visual assessment, without considering microbiological tests. Meeting food safety requirements set by government regulations remains a challenge to almost all food processors. This paper reviews the impact of post-slaughter handling on carcass quality and its implications for meat safety during the distribution stage in the formal and informal sectors in South Africa. It also details how meat handling in the informal meat trade exposes consumers to high health risks and recommends that governments create legislation that would be applicable to carcasses produced in the informal sector to align this sector with the regulations governing food production.