Contribution to the study of avocado honeys by their mineral contents using inductively coupled plasma optical emission spectrometry

Avocado honey samples were analyzed by inductively coupled plasma optical emission spectrometric. First, the botanical origin of the honeys was confirmed by melissopalynological analysis. Twenty-four minerals were quantified for each honey sample. The elements Al, Ba, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, S, Se, Si and Zn were detected in all samples; seven elements were very abundant (Ca, K, Mg, Na, P, S and Si), six were not abundant (Al, Cu, Fe, Li and Zn) and 11 were trace elements (As, Ba, Cd, Co, Cr, Mo, Ni, Mo, Pb, Se, Sr and V).     

Evaluation of alternatives for the evolution of palm oil mills into biorefineries

Six alternatives for the conversion of an average Colombian palm oil mill (30 t h⁻¹ of fresh fruit bunches (FFB) into biorefineries were evaluated. The alternatives studied were: (C1) Production of biogas from the Palm Oil Mill Effluents (POME), (C2) Composting of empty fruit bunches (EFB) and fiber, (C3) Biomass combustion for high pressure steam combined heat and power, (C4) Pellets production, (C5) Biochar production and, (C6) Biochar and bio-oil production. The available biomass could result in up to 125 kWh of electricity, 207 kg of compost, 125 kg of pellet, 44 kg of biochar and 63 kg of bio-oil per metric ton of FFB. The global warming potential (GWP), eutrophication potential (EP), net energy ratio (NER), capital expenditures (CAPEX), operational costs (OPEX), net present value (NPV) and internal rate of return (IRR) were calculated for all the alternatives. GHG reductions of more than 33% could be achieved. Anaerobic digestion and composting contributed to 30% reduction of the EP. The CAPEX for all of the biorefinery alternatives studied varies between 0.7 $ t⁻¹ and 2.8 $ t⁻¹ of FFB. The OPEX varies between 1.6 $ t⁻¹ and 7.3 $ t⁻¹ of FFB. The NPV for viable scenarios ranged between 2.5 million and 13.9 million US dollars. The IRR calculated varied between 3% and 56% and the payback periods were between 3 and 8 years. The total extra incomes reached values up to 15.2 $ t⁻¹ of FFB. Overall the pellets production biorefinery was the preferred alternative.     

Logistics cost analysis of rice straw pellets for feasible production capacity and spatial scale in heat utilization systems: A case study in Nanporo town,Hokkaido, Japan

Rice straw is a promising renewable energy source because it is abundantly available in Asia. This study conducted a case study of logistics cost analysis for rice straw pellets by considering all stages in the supply chain to define the main factors affecting the selling price of rice straw pellets: collection (job-commission or employment of part-time workers), transportation, storage (vinyl greenhouses or storage buildings with larger capacity), pelletizing, and delivery to users with biomass boilers. The selling price was found to be strongly dependent on the production capacity because the investment cost for the pellet production facility had a significant effect of economies of scale. A production capacity of larger than 1500 t y⁻¹ is required for rice straw pellets to compete with wood pellets and fossil fuels in the studied Japanese context if the subsidy rate for the investment is 50%, part-time workers conduct the collection, and rice straw is stored in the storage buildings. Our sensitivity analysis also showed an economically feasible spatial scale: for example, rice straw should be collected within a 20 km radius and the users should be within a 38 km radius when the production capacity is 1500 t y⁻¹. In addition, other critical factors related to the collection of rice straw from the paddy fields and transportation of rice straw rolls to storage were identified as planning factors to further reduce the total logistics cost of rice straw pellets.     

Socio-economic hurdles to widespread adoption of small-scale biogas digesters in Sub-Saharan Africa: A review

The unsustainable use of fossil fuels has led to increased awareness and widespread research on the accessibility of renewable energy resources such as biogas. Biogas is a methane rich gas that is produced by anaerobic fermentation of organic material. Despite its potential to replace biomass in Africa, where over 70% of the households use wood fuel and agricultural waste for cooking, biogas technology has not been adopted by Sub-Saharan African countries compared to their Asian counterparts. This paper examines the socioeconomic constraints to adoption of biogas in Sub-Saharan Africa and explores factors that could enhance adoption of the technology. These include standardization and quality control, as well as an approach of integrated farming using biogas and slurry. The article recommends mobilization of local and external funds to promote biogas, use of ready to use funds such as the Clean Development Mechanisms in overcoming the initial construction costs of biogas units, and formation of user and disseminator associations to reduce costs by joint procurement and linkage to finance. It further advocates the promotion of multiple uses of biogas for purposes other than cooking and lighting. It is expected that widespread adoption of the technology could lead to self-sufficiency in household energy provision for cooking. This would facilitate environmental management and economic development in Sub-Saharan Africa.     

What is the potential for biogas digesters to improve soil fertility and crop production in Sub-Saharan Africa?

Three alternative soil amendments of organic wastes are considered: application of untreated animal manures, bioslurry from biogas digestion, composted materials, and biochar produced by pyrolysis cook-stoves. Application of untreated manures provides high input of available nutrients, which results in an initial flush in crop growth. However, risks of losing nutrients are high because manure is usually applied before sowing to avoid reduced yields due to phytotoxicity, resulting in increased losses by leaching or volatilization. Furthermore, the heterogeneous nature of untreated manures results in immobilization of nutrients by carbon-rich materials. A greater amount of nutrients are potentially available to crops from applied bioslurry. Typically 5–10% of the nitrogen is lost during anaerobic digestion, but bioslurry provides immediately available nutrients that can be applied as needed, so reducing risks of nutrient loss. If, however, bioslurry was applied in a single dose, losses would be similar in magnitude to untreated manures. Risks of nutrient losses are also lower when wastes are applied as composts, but in contrast to bioslurry, this is because the concentration of immediately available nutrients is very low, most nutrients being held in organic form that will become available only slowly over the growing season. Composts provide an option for single dose application, but a larger proportion of nitrogen is lost during composting (26–51%) than during anaerobic digestion (5–10%). Losses of nitrogen during pyrolysis are also very high (70–90%), but biochar can reduce losses of native soil nutrients by providing exchange sites that hold nutrients in the soil.     

Critical parameters in cost-effective alkaline extraction for high protein yield from leaves

Leaves are potential resources for feed or food, but their applications are limited due to a high proportion of insoluble protein and inefficient processing. To overcome these problems, parameters of alkaline extraction were evaluated using green tea residue (GTR). Protein extraction could be maximized to 95% of total protein, and, after precipitation by pH adjustment to 3.5, 85% of extracted protein was recovered with a purity of 52%. Temperature, NaOH amount, and extraction time are the protein yield determining parameters, while pH and volume of extraction liquid are critical parameters for production cost. The cost of energy and chemicals for producing 1 t GTR proteins is minimized to 102€, and its nutritional value is comparable to soybean protein. Furthermore, this technology was successfully applied to other sources of biomass and has potential to be used as a part of an integrated bio-refinery process.     

Predicting Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) populations and associated grain damage in smallholder farmers’ maize stores: A machine learning approach

Prostephanus truncatus is a notorious pest of stored-maize grain and its spread throughout sub-Saharan Africa has led to increased levels of grain storage losses. The current study developed models to predict the level of P. truncatus infestation and associated damage of maize grain in smallholder farmer stores. Data were gathered from grain storage trials conducted in Hwedza and Mbire districts of Zimbabwe and correlated with weather data for each site. Insect counts of P. truncatus and other common stored grain insect pests had a strong correlation with time of year with highest recorded numbers from January to May. Correlation analysis showed insect-generated grain dust from boring and feeding activity to be the best indicator of P. truncatus presence in stores (r = 0.70), while a moderate correlation (r = 0.48) was found between P. truncatus numbers and storage insect parasitic wasps, and grain damage levels significantly correlated with the presence of Tribolium castaneum (r = 0.60). Models were developed for predicting P. truncatus infestation and grain damage using parameter selection algorithms and decision-tree machine learning algorithms with 10-fold cross-validation. The P. truncatus population size prediction model performance was weak (r = 0.43) due to the complicated sampling and detection of the pest and eight-week long period between sampling events. The grain damage prediction model had a stronger correlation coefficient (r = 0.93) and is a good estimator for in situ stored grain insect damage. The models were developed for use under southern African climatic conditions and can be improved with more input data to create more precise models for building decision-support tools for smallholder maize-based production systems.     

Sensory acceptability and personality traits both determine which contexts are preferred for consumption of alcoholic cocktails

Alcoholic cocktails are consumed in very different situations and then consumers may differ in their favorite context to drink a cocktail. Diversity in the preferred context of cocktail consumption may reflect individual differences in taste responsiveness and personality traits as well as cocktail liking. This study aims at: 1) extending the efficacy of a coupled semiotic and statistical methodology for text analysis in uncovering aspects of preferred contexts of cocktail consumption; 2) testing if specific preferred contexts of cocktail consumption are related to individual differences; 3) investigating the relationships between preferred context to have cocktails and patterns of liking for cocktails. 159 cocktails consumers were characterized by personality traits, cocktail involvement, alcoholic beverages intake and PROP taster status and were asked to describe their preferred context to consume an alcoholic cocktail. Consumers were then asked to taste in blind conditions and rate their liking of six alcoholic aperitif cocktails. Three thematic clusters were identified (relax, sociability, aperitif). The relax lovers preferred a comforting context to have a cocktail; these consumers expressed a lower liking for the six evaluated samples than aperitif lovers but resulted more involved with cocktails as compared to the cluster sociability. This latter group of consumers focused on social aspects and novelty; they reported a higher intake of spirits than the cluster aperitif and showed higher scores in sensation seeking and disinhibition than the other clusters. The cluster aperitif described their favorite context as a “before dinner” situation; they were more involved with cocktails than the sociability cluster. Finally, the three clusters did not differ in PROP taster status distribution. The approach has proven to be useful to collect information and to segment consumers on the preferred aspects of cocktail experience. The study showed that consumer clusters with different preferred context for cocktail consumption differ in liking for the cocktails, personality traits, attitudes and alcohol intake.     

Comparison of air freezing,liquid immersion freezing and pressure shift freezing on freezing time and quality of snakehead (Channa Argus) fillets

The objective of this study was to investigate the freezing time and quality differences in Snakehead fillets frozen by pressure shift freezing (PSF), conventional air freezing (AF) and liquid immersion freezing (LIF) at −20 °C, −40 °C and − 60 °C, respectively. The results showed that liquid immersion freezing at −60 °C maintained the quality best, with a freezing time of 3.62 min and the cross sectional area of 209.11 um². Air freezing at −20 °C had the longest freezing time (184.58 min) and the largest cross sectional area (4470.79 um²), and lowest hardness and springiness of the fillets. Pressure shift freezing did not demonstrate the well established advantages of maintaining better product quality found in similar technique with some other foods. The samples of pressure shift freezing also had higher thawing loss and free water ratio after thawing. Therefore, the liquid immersion freezing at lower temperatures was demonstrated to better maintain the quality of frozen products and held significant potential for commercial application.Industrial relevanceFreezing is a widely used method for extending the shelf life of aquatic products, but some freezing methods, especially the slower ones, often lead to the decrease in the quality and commercial value of frozen products during storage. This paper explored the comparison of industrially used freezing techniques (air freezing and liquid immersion freezing) with the novel pressure shift freezing technique. Liquid immersion freezing at −60 °C was found to be the preferred freezing method for Snakehead fillets, which maintained better frozen product quality, with a simple freezing process and low cost.