Effect of high pressurized carbon dioxide on Escherichia coli

Carbon dioxide at high pressure can retard microbial growth and sometimes kill microorganisms depending on values of applied pressure, temperature and exposure time. In this study the effect of high pressurised carbon dioxide (HPCD) on Escherichia coli was investigated. Culture of E. coli was subjected to high pressurised carbon dioxide at 15, 25 and 35 bar, and varying exposure times of 20, 40, 60 and 90 minutes at room temperature (27 oC). Microbial inactivation increased with pressure and exposure time. For the first 20 minutes reduction of viable microbial cells was 18%, 30% and 36% at 15, 25 and 35 bar, respectively. Higher microbial inactivation values were achieved at 40, 60, and 90 minutes. Decimal reduction times were 127, 93 and 75 minutes at 15, 25, and 35 bar, respectively. The pH values of treated samples decreased with increasing pressure and treatment time from approximately neutral to 5.71 at 15 bar, and 5.02 at 35 bar. It was concluded that high pressurised carbon dioxide has antimicrobial effect on E. coli bacteria. With further studies, HPCD microbial deactivation can be used for foods preservation as a alternative technology to conventional heat pasteurisation and sterilization

Improvement of Hydraulic Press for Vegetable Oil Expression in Rural Areas

Cultivation of oil producing crops especially Jatropha and croton as source of vegetable oil for biodiesel production is being encouraged in rural areas. To recover oil from seed, manual press is the feasible method in rural areas where there is no electricity. Research was conducted to improve hydraulic oil press machine for rural application. Factorsaffecting oil recovery were found to be: moisture content of seeds, operating pressure, seed oil content, and the amount of seeds pressed per batch. Percentage oil recovery was improved by reducing diameter of press cylinder, hence increasing expression pressure, and either reducing amount of seed processed per batch or placing disk within the seeds to improve oil flow. The maximum vegetable oil recovered from Jatropha seeds at a pressure of 20.8 MPa after improvement was 57.5% of the total oil in seeds. There was no significant difference in terms of oil recovery between pressing whole seeds or milled seeds. Suggested further improvement includes: higher pressure than 20.8 MPa, reduced radial distance travelled by oil and replacement of hydraulic jack with a self retracting double acting hydraulic power cylinder to reduce batch cycle

Effects of Ripeness and Blending Speed on the Extraction Yield and Physical Chemical Properties of Low Viscosity Banana Juice

Low viscosity banana juice can be extracted from banana by blending and pressing the resulted semi-solid pulp to separate the juice. This juice extraction technology is relatively new and further studies to understand key parameters for juice release is vital for scaling up production and commercialisation. This study, investigated the influence of blending speed and ripeness stage on banana juice yield using two banana cultivars; the East African highland banana (Mbile) and the exotic banana (Pisang awak). Types of sugars and organic acids in the juice were analysed using an HPLC. Changes with ripening of fruit firmness, juice pH and soluble solids were also examined. The juice yield increased significantly (p < 0.05) with increasing blending speed and ripeness stage for all cultivars. The Mbile cultivar from Kagera had the highest juice yield of 82.35%, followed by Mbile cultivar from Kilimanjaro with 75.30% and Pisang awak cultivar with juice yield of 62.50%. The highest juice yield for all cultivars was achieved at 3500 rpm blending speed and ripeness stage 5. Fructose and glucose sugars increased significantly (p < 0.05) with ripeness, while sucrose showed insignificant changes. Malic and citric acids were observed to increase significantly (p < 0.05) during ripening in all banana cultivars. Keywords: East African highland banana, Banana juice extraction, Blending speed, Low viscosity banana juice

Proteomic potential of East African Highland Bananas (EAHBs) for banana juice extraction: comparison between juice-producing and cooking cultivars

This study investigated the proteomic difference between juice-producing and cooking EAHBs to clarify the role of protein in the production of banana juice. A comparative study was carried out to determine protein content, molecular weight distributions, and amino acid profile of the pulps of ten different (five juice-producing and five cooking) banana cultivars. There was low variability in crude protein content of banana cultivars, the level fell within the range of 0.80 g/100 g to 1.02 g/100 g. SDS-PAGE results visualised that the cultivars had similar molecular weights, ranging between 10 kDa and 76 kDa. The HPLC analysis showed that the relative compositions of amino acids differed significantly (p <= .05) within and between juice-producing and cooking cultivars. Both banana cultivars had a significantly higher amount of glutamic and aspartic acids, but significantly lower concentrations of tyrosine, methionine. The results suggest that protein content, molecular weight, and amino acid composition of banana cultivars are not the major factors in determining a banana\u27s ability to release juice

Physico-chemical Properties of Mechanically Extracted Banana Juice at Different Ripening Stages

This paper presents the findings of a study on physico-chemical properties of low viscosity banana juice from five banana cultivars: Pisang Awak (PSA) an ABB genome, Yangambi km5 (YKM5) an AAA genome and cultivars from AAA-EA genome, namely Mbilabile, Ndeshi and Mlonga. Low viscosity banana juice was extracted using improved mechanical method at five ripening stages. The physico-chemical properties significantly varied according to cultivars and ripening stages (p < 0.05). Yields, total soluble solids (TSS), titratable acidity (TA) and pH were in the range of 19.50–74.03%, 7.33–27.64 ºBrix, 0.37–0.76% malic acid equivalent and 4.09–4.70, respectively. Yields decreased in the order of Mbilabile > Ndeshi > Mlonga > YKM5 > PSA whereas the total soluble solids increased as follows Mlonga < Mbilabile < Ndeshi < YKM5 < PSA. Furthermore, ashes and mineral contents decreased with ripening stages whereas the low viscosity banana juice was rich in potassium and magnesium. Finally, the study recommends stage 5 of the ripeness as ideal for producing low viscosity banana juice. Keywords: Mechanical extraction, Banana cultivar, Ripening stage, Tannin, Banana juic

Effects of Drying, Packaging Conditions and Storage Time on Proximate Composition of Chia Seeds (Salvia hispanica)

The effects of drying, packaging conditions and storage time on proximate composition of chia seeds were investigated. Chia seeds were dried at 63 °C for 30 min (low-temperature long time–LTLT) and at 75 °C for 30 s (high-temperature short time-HTST) using dry oven, air/vacuum-packed and stored for ten weeks. The effect of heat processing (drying) on chia seeds had significant difference (p < 0.05) in ash, fiber and fat contents while there was no significant difference (p > 0.05) in moisture and protein contents. Except for fiber content, there was no significant difference (p > 0.05) in moisture, ash, fat and protein of chia seeds dried at LTLT and HTST before storage. During storage time, there was significant decrease of proximate composition of chia seeds and the decline was the lowest in raw chia seeds followed by seeds dried at HTST and the highest by seeds dried at LTLT. In both drying conditions, ash, fat and protein contents were significantly greater in vacuum than in air packaging although the impact was vice versa for moisture and fiber contents. On the expense of improved shelf life, palatability and digestibility expected as effect of drying, this study suggests HTST and vacuum packaging for storage of chia seeds. Keywords: Chia seeds; proximate composition; drying; packaging condition; storage

Co-composting of banana peel and orange peel waste with fish waste to improve conversion by black soldier fly (Hermetia illucens (L.), Diptera: Stratiomyidae) larvae

Black soldier fly (BSF) larvae composting is a promising waste treatment that can add value to available biodegradable waste. However, substrates that have low protein content and contain complex molecules (e.g. fruit peels) are not easily degraded by the larvae. This study evaluated the impact on the BSF larvae composting efficiency of co-composting different mixtures of banana and orange peels with incremental increase of fish waste. Mixtures (in total 50 distinct mixtures) of varying proportions of banana peels, orange peels and fish waste were evaluated. BFSL fed on orange peel and banana peel mixtures, containing no fish waste, resulted in a lower biomass conversion efficiency (4.5% +/- 1.3) on a volatile solids (VS) basis (BCEvs). Co-composting the fruit peels with fish waste increased the biomass conversion efficiency and the highest BCEvs (25%) was attained when 75% fish waste was included. However, the BCEvs varied greatly (18.0% +/- 5.8), likely due to varying fish waste composition. A 25% fish waste inclusion resulted in more than twice as high BCEvs (12.3% +/- 2.1) compared to when no fish waste was included. As the conversion efficiency variance increased with increasing fish waste inclusion, it was recommended to keep the inclusions of the fish waste to around 25% of the total mixture, in order to increase the reliability of the BSF larvae composting efficiency

Evaluation of Natural Antifungal Compounds from Artemisia afra and its Effectiveness on Prevention of Aflatoxins

Artemisia afra is a medicinal plant with antimicrobial activities, known to treat tuberculosis, measles, cough, and influenza. In consequence, its applications have increasingly become pivotal to control various microbes which cause different diseases. This study therefore, evaluated the chemical composition and the antifungal activity of A. afra essential oil. The extraction of essential oil was done using steam distillation. The essential oil chemical composition was analysed by GC-MS. The analysis revealed 19 compounds from A. afra. The main compounds were borneol (71.529%), terpinen-4-ol (8.582%), β-thujone (3.283%), β-terpineol (2.590%), α-terpineol (1.791%), chrysanthenone (1.507%), myrtenal (1.393%), eucalyptol (1,8-cineole) (1.263%), cis-sabinene hydrate (1.172%) and trans-carane, 4,5-epoxy (1.088%). The growth and aflatoxin production inhibitions against A. flavus were determined via antifungal and antiaflatoxigenic bioassays of the A. afra essential oil at the concentration range of 10–50 µL/mL using a poisoned-food method. The quantification of the aflatoxins production was carried out using high-performance liquid chromatography. The antifungal activity of A. afra essential oil was effective against A. flavus with growth inhibition of 99.97–99.99% and controlled aflatoxins production by 99.25–99.63%. The results indicated that A. afra essential oil can become an alternative natural fungicide for the control of A. flavus growth and aflatoxins production. Keywords: Artemisia afra; essential oil; A. flavus; aflatoxins; GC-M

Optimization of process parameters for mechanical extraction of banana juice using response surface methodology

Banana juice is traditionally processed under very basic conditions characterized by low efficiency and poor hygiene. Introduction of mechanical pressing has created opportunities for upgrading banana juice production, but more knowledge is needed about critical factors for juice release and about optimizing extraction for higher yield and quality. This study sought to identify and optimize important factors associated with juice release. This was done using an experimental design (Box–Behnken design of response surface methodology) involving three levels of three independent variables: blending speed (1000–3500\ua0rpm), extraction time (30–240\ua0s), and stage of ripeness (3–7). A second-order polynomial equation was created to describe the relationship between dependent and independent variables. The results showed that juice yield increased with blending speed, extraction time, and stage of ripeness, whereas the quadratic (squared) effect of these factors was a significant decrease in juice yield. Optimum juice yield (57.5%) was obtained at blending speed 2650\ua0rpm, extraction time 162\ua0s, and ripeness stage 5. Analysis of variance showed that stage of ripeness significantly (p ≤ 0.001) affected juice yield. This novel information on the underlying factors in banana juice extraction and on optimization of the process can be used to improve mechanical extraction of low-viscosity, clear banana juice and achieve scaling-up of banana juice processing

Food industry waste - An opportunity for black soldier fly larvae protein production in Tanzania

Black soldier Ily larvae composting is an emerging treannent option with potential to improve biowaste valorization in cities of low-income countries. This study surveyed the current generation and management status of food industry biowaste and their availability and suitability as potential feedstock for black soldier Ily larvae (BSFI.) composting treatment in three Tanzania cities, Dar es Salaam, Mwanza, and Dodoma. Biowaste-generating food industry companies (n = 29) in the three cities were found to produce banana peels, mango seeds, sunflower press cake, brewery waste, and coffee husks in large quantities (similar to 100,000-1,000,000 kg y(-1)). Around 50 % of these companies (16/29), primarily vegetable oil companies (10/11), either sold or gave away their waste as animal feed, while most companies (9/11) with unutilized food industry waste landfilled the generated biowaste. Multi-criteria analysis based on substrate availability criteria identified banana peels, mango seeds, and coffee husks with total score points of a >= 10/12 as the most suitable feedstock for BSFL composting. However, multi-criteria analysis based on physicalchemical criteria identified brewery waste and sunflower press cake with total score points of a >= 11/15 as the most suitable feedstock. Combined availability and physical-chemical properties of individual biowastes showed that all identified types of food industry biowaste can be suitable feedstock for producing BSFL biomass for protein production, but certain waste streams needed to be mixed with other waste streams prior to BSFL-composting to ensure sufficient availability and provide a balanced nutritional profile compared with the single-source biowastes. This study concluded that large volumes of food industry waste are being generated from food industry companies in Tanzania and there is need to establish new biowaste management interventions for resource recovery. Furthermore, for interested stakeholders in the waste management business, multi-stream BSFI.-composting can be a suitable solution for managing and closing nutrient loops of the unutilized food industry biowaste in Tanzania and in other similar settings globally