Aquaponics: a sustainable alternative to conventional agriculture in Egypt - a pilot scale investigation

Conventional agriculture has been widely used to overcome food scarcity in Egypt, but in turn created new environmental, social, and economic problems. Aquaponics has a huge potential as a sustainable solution since it demonstrates promising results for urban food development while providing new entrepreneurship and start-up opportunities. Although it presents a big opportunity especially for developing countries like Egypt, it still requires further studies and researches to fully overcome foreseen challenges. This study discusses the possibility of implementing aquaponics as an alternative to conventional agriculture in Egypt through a comparison between aquaponics and conventional agriculture. The first section of this investigation analyzes the economic feasibility of aquaponics in terms of capital and operational expenditure costs. Then, an experimental comparative study is carried out examining two pilot-scale aquaponics systems (Deep water Culture system and Integrated Aqua-Vegaculture system), where crop quality (vitamins, heavy metals, and pesticides residues) of the two systems has been compared among each other, as well as to that of the commercially available organic food available in supermarkets. Results indicated that both systems produce high-quality safe organic food. The economic feasibility analysis indicated that Integrated Aqua-Vegaculture System is producing more crops with a wider variety of almost 20% less capital expenditure and operational expenditure costs. Fish production for both systems was close, yet slightly higher in Deep Water Culture. Although, on the short term, aquaponics entails relatively high capital and operational expenditure costs compared with conventional agriculture; yet, on the long term, it is more profitable, while saving up to 85% of the water wasted by conventional farming techniques. Finally, the study discusses the main limitations, drawbacks, and future of aquaponics in Egypt where public awareness and a new mindset are needed to highlight the link between agriculture and sustainability.

High Occurrence Rate and Contamination Level of Bacillus cereus in Organic Vegetables on Sale in Retail Markets

Organic foods have risen in popularity recently. However, the increased risk of bacterial contamination of organic foods has not been fully evaluated. In this study, 100 samples each of organic and conventional fresh vegetables (55 lettuce samples and 45 sprout samples) sold in South Korea were analyzed for aerobic bacteria, coliforms, Escherichia coli, and Bacillus cereus. Although the aerobic bacteria and coliform counts were not significantly different between the two farming types (p > 0.05), the occurrence rate of B. cereus was higher in organically cultivated vegetables compared with those grown conventionally (70% vs. 30%, respectively). The mean contamination level of B. cereus-positive organic samples was also significantly higher (1.86 log colony-forming unit [CFU]/g vs. 0.69 log CFU/g, respectively) (p < 0.05). In addition, six samples of organic vegetables were found to be contaminated with B. cereus at over 4 log CFU/g categorized as unsatisfactory according to Health Protection Agency guideline. The relatively higher occurrence rate of B. cereus in organic vegetables emphasizes the importance of implementing control measures in organic vegetable production and postharvest processing to reduce the risk of food poisoning.

Development of a cost-effectiveness analysis of leafy green marketing agreement irrigation water provisions

An analysis of the effectiveness of meeting the irrigation water provisions of the Leafy Green Marketing Agreement (LGMA) relative to its costs provides an approach to evaluating the cost-effectiveness of good agricultural practices that uses available data. A case example for lettuce is used to evaluate data requirements and provide a methodological example to determine the cost-effectiveness of the LGMA water quality provision. Both cost and field data on pathogen or indicator bacterial levels are difficult and expensive to obtain prospectively. Therefore, methods to use existing field and experimental data are required. Based on data from current literature and experimental studies, we calculate a cost-efficiency ratio that expresses the reduction in E. coli concentration per dollar expenditure on testing of irrigation water. With appropriate data, the same type of analysis can be extended to soil amendments and other practices and to evaluation of public benefits of practices used in production. Careful use of existing and experimental data can lead to evaluation of an expanded set of practices.

Effect of abiotic elicitation on main health-promoting compounds, antioxidant activity and commercial quality of butter lettuce (Lactuca sativa L.)

The study presents changes in the phytochemical levels, antiradical activity and quality of lettuce caused by different chemical elicitors: arachidonic acid (AA), jasmonic acid (JA), and abscisic acid (ABA). The application of 1 μM and 100 μM JA induced an increase in the concentration of phenolic compounds, including flavonoids and phenolic acids. Flavonoid levels were also increased after treatment with 100 μM AA and ABA. Some of the elicitor concentrations used also caused an increase in the levels of other phytochemicals, such as chlorophyll a (1 μM and 100 μM AA, 50 μM ABA); chlorophyll b (100 μM AA); carotenoids (100 μM AA, 1 μM JA and 100 μM ABA) and vitamin C (100 μM AA, 100 μM JA). The highest antiradical activity was noted after treatment with 100 μM AA, 100 μM JA. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) scavenging ability was positively and significantly correlated with flavonoid, chlorophyll and carotenoid levels. These results may suggest that the antiradical activity of lettuce was determined not only by phenolics, but also by other bioactive compounds. Elicitation did not change the sensory quality of lettuce. Therefore, treatment with elicitors could be a useful tool for improving the health-promoting qualities of lettuce without the loss of sensory quality.

Monitoring of nitrites and nitrates levels in leafy vegetables (spinach and lettuce): a contribution to risk assessment

BACKGROUND

Nitrites and nitrates are compounds considered harmful to humans and the major part of the daily intake of nitrates in foodstuffs is related to vegetable consumption. In this work, 150 leafy vegetables samples (75 spinach and 75 lettuce) were analysed in order to assess the levels of nitrites and nitrates. The analyses were carried out by a validated ion chromatography method and the samples with nitrate concentrations higher than legal limits and/or with quantifiable concentrations of nitrites were confirmed by an alternative ion chromatography method.

RESULTS

Nitrate levels higher than legal limits were detected both in spinach (four samples) and in lettuce (five samples). Nitrite residues were registered both at low concentrations--lower than 28.5 mg kg⁻¹ (12 spinach samples)--and at high concentrations, up to 197.5 mg kg⁻¹ (three spinach and one lettuce sample).

CONCLUSION

Considering the non-negligible percentage of 'not-compliant' samples for nitrates (6.0%), control is needed. Moreover, it is possible to suggest the introduction in the Communities Regulations of a 'maximum admissible level' for nitrites in leafy vegetables.

Modelling growth of Escherichia coli O157:H7 in fresh-cut lettuce submitted to commercial process conditions: chlorine washing and modified atmosphere packaging

Fresh-cut iceberg lettuce inoculated with Escherichia coli O157:H7 was submitted to chlorine washing (150 mg/mL) and modified atmosphere packaging on laboratory scale. Populations of E. coli O157:H7 were assessed in fresh-cut lettuce stored at 4, 8, 13 and 16 °C using 6-8 replicates in each analysis point in order to capture experimental variability. The pathogen was able to grow at temperatures ≥8 °C, although at low temperatures, growth data presented a high variability between replicates. Indeed, at 8 °C after 15 days, some replicates did not show growth while other replicates did present an increase. A growth primary model was fitted to the raw growth data to estimate lag time and maximum growth rate. The prediction and confidence bands for the fitted growth models were estimated based on Monte-Carlo method. The estimated maximum growth rates (log cfu/day) corresponded to 0.14 (95% CI: 0.06-0.31), 0.55 (95% CI: 0.17-1.20) and 1.43 (95% CI: 0.82-2.15) for 8, 13 and 16 °C, respectively. A square-root secondary model was satisfactorily derived from the estimated growth rates (R(2) > 0.80; Bf = 0.97; Af = 1.46). Predictive models and data obtained in this study are intended to improve quantitative risk assessment studies for E. coli O157:H7 in leafy green products.

Economic analysis of cucumber and lettuce intercropping under greenhouse in the winter-spring

The economical analysis complements the evaluation of the intercrop systems efficiency, considering besides the physical production of crops, the price of products according to their quality classification and time of the year. Intercropping systems of lettuce and cucumber in two plant populations under greenhouse were economically evaluated in winter-spring, in Jaboticabal City, São Paulo State, Brazil. The total operating cost (TOC) of cucumber and lettuce as sole crop and intercropping were estimated, as well as gross revenue (GR) and operating profit (OP). The labor for the crops was the component with greater participation in the TOC of crops in intercropping and single crop. Greater GR and OP were observed in intercrops established by transplanting lettuce and cucumbers on the same day. Considering the operating profit and the land efficient ratio, it is recommended the intercropping of lettuce transplanted until 10 days after the transplanting (DAT) of cucumber with two rows per plot, and at 0 DAT of cucumber grown with a row plot.