Osmotic dehydration of foods : development of predictive models

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Development of business capacity and organization of commercial business of farmer based organizations in the northern intervention zone in Ghana: A case study of nine-farmer based organizations

"El análisis de supervivencia implica el seguimiento de los individuos a lo largo del tiempo t. Es común que durante el periodo de observación se presenten condiciones que compliquen el estado de los individuos. De esta manera, un evento favorable es observar de manera exacta el tiempo de ocurrencia del suceso de interés. En términos generales el análisis de supervivencia tiene como objetivo estudiar el tiempo de vida (o falla) del evento que se está analizando. Las funciones de riesgo son una herramienta muy importante en supervivencia, ya que estas describen la posibilidad de falla en un momento determinado, a través de ellas es posible determinar una distribución del tiempo de falla. La función de riesgo juega un papel importante en la supervivencia ya que por lo general esta función puede aumentar o disminuir, en intervalos de tiempo muy peque˜nos, estos tipos de cambio son comunes en los estudios médicos como en enfermedades de cáncer, trasplantes de corazón o riñón, donde los pacientes tienen un riesgo cada vez mayor durante el período de prácticas y una disminución de riesgos después de este período de adaptación. En un estudio de la recuperación de cáncer de mama, se ha observado que se produce la máxima mortalidad después de tres años y luego disminuye lentamente durante un período de tiempo fijo.

Comparative behaviour of cellulosic and starchy plant materials during osmotic dehydration

Abstract: Osmotic dehydration studies on two cellulosic plant materials – Golden Delicious and Cox apple – and two starchy plant materials – banana and potato – showed that the amount and rate of water loss occurred in the following descending order: Golden Delicious > Cox > potato > banana. Temperature, concentration and immersion time of samples in the osmotic solution played a significant effect on amount and rate of water loss in all commodities in a descending order as follows: 55 > 40 > 32.2 ◦C; 0.70 > 0.60 > 0.50 > 0.40 g kg−1; and 30 > 60 > 90 > 120 min, respectively. A corresponding uptake of solids from the osmotic solution occurred, the rate been greatest over the first 30min, before declining significantly thereafter. The diffusion coefficients for water loss (Deff,w) measured by the method of slopes on the water loss rate curves conducted at 32.2, 40 and 55 ◦C for 0.40,0.50, 0.60 and 0.70 g kg−1 sucrose concentration solutions were higher for cellulosic plant materials than starchy plant materials. Significant variations occurred in efficiency index (WL/SG) between cellulosic and starchy plant materials

Osmotic dehydration kinetics of apple, banana and potato

Osmotic dehydration rate constants were established for the rate constants k1, k2 and k3 for the first, second and third falling periods of osmotic dehydration of Golden Delicious, Cox, banana and potato by the method of slopes from the rate of water loss curves of the various materials. The rate constants k1, k2 and k3 were identified in Golden Delicious and Cox and k1 and k2 were identified in banana and potato. The Arrhenius equation was applied to evaluate the reaction rate (k) and its temperature dependence. The Arrhenius plots of rate constants k1, k2 and k3 for Golden Delicious, Cox, banana and potato were established, which were excellent under some treatments in the various plant materials. The coefficient of determination (R2) for the rate constant k3 for Golden Delicious in 60% sucrose solution was 0.99. Similar values of R2 were obtained for Cox, banana and potato. In some cases the Arrhenius plots of the rate constants k1, k2 and k3 were scattered. The highest activation energies were observed in the rate constant k1, a reflection of the highest rate constants estimated from the falling rate curves for water loss over immersion time

Physicochemical and functional properties of dried okra (Abelmoschus esculentus L.) seed flour

The physicochemical and functional properties of dried okra seed flour of two genotypes Agbagoma and Balabi were evaluated. The samples Agbagoma and Balabi had 8.90%–9.00% moisture, 16.80%–17.40% protein, 47.80%–48.00% fat, 7.70%–7.80% ash, and 18.20%–18.40% carbohydrate. The mean values of functional properties revealed significant differences (p < .05) between okra seed flour samples studied. The samples’ bulk density range was 0.80–0.83 g/ml. Water absorption capacity and oil absorption capacity ranged from 511.65% to 504.32% and 88.38 to 160.67%, respectively. The solubility was 14.10% for Agbagoma and 10.97% for Balabi, whereas swelling power was 16.37% and 14.68% for Agbagoma and Balabi, respectively. All pasting properties except peak time and pasting temperature of Agbagoma seed flour were higher than those of Balabi seed flour. The study revealed that dried okra seed flour is rich in nutrients, which could be used for baking and fortification of foods

Potential of calorimetry to study osmotic dehydration of food materials

A new method, thermocalorimetry, was developed to study osmotic dehydration. The kinetic data from the method was comparable to more traditional methods in the determination of rate constants for water loss. Thermocalorimetry measurements indicated a 2–3 kinetic phases, a relatively rapid process followed by a relatively slow process. The first phase is possibly due to water removal from the cut surfaces and damaged cells and the initiation of water transfer from cells near the surface of the tissue. The second phase of heat output which is less rapid occurred in the next hour possibly associated with the loss of water due to the movement of free water from the intercellular spaces of samples to the external sucrose solution. The third kinetic phase, a relatively slow process is possibly due to loss of water from the extracellular volume of the cells and intracellular volume of the cells across the cell membrane in the sample to the external sucrose solution

Microbial deterioration of white variety sweet potato (Ipomoea batatas) under different storage structures

Post-harvest protection of white variety sweet potato (Ipomoea batatas) has been dealt with rarely in the past, although it is comparatively easy to grow and has high consumer acceptability in Ghana. Microbial deterioration of sweet potato roots stored in three different storage structures was studied. The sweet potato roots initially cured for 7 and 14 days were stored in traditional, pit, and clamp storage structures for a maximum of 28 days. For the 7 days-cured sweet potato roots, the bac­teria population in the three different storage structures increased by 1.2-2.3 log cfu/g whereas for the 14 days-cured roots, the bacteria population was 0.1-1.0 log cfu/g within 28 days of storage. The fungal population in the 14 days-cured sweet potato roots was higher than in the 7 days-cured sweet potato roots by 0.6-1.6 log cfu/g for 28 days of storage. For both the 7 and 14 days-cured sweet potato roots, the sweet potato roots stored for 28 days in the three different storage structures had a higher microbial count compared to the sweet potato roots stored for 14 days. Aspergillus flavus was the most dominant fungal species occurring in all of the three different storage structures followed by A. niger, Rhizopus stolonifer, Tricho-derma viride, Fusarium oxysporum, Penicillium digitatum, Cladosporium herbarum,and Aspergillus ochraceus, in that order

Identifying Biomass-Based Value Webs for Food Security in Sub-Saharan Africa: A Systems Modeling Approach

Food security in Sub-Saharan Africa (SSA) is dependent on complex networks of interconnected actors and the flows of resources (biomass, capital) and information among them. However, the degree to which actors and value chains of different crops are in fact interconnected and their current systemic influence on food security are unclear. Therefore, the concept of “value webs” to better capture the complexity within the networks emerges. Biomass-based value webs of selected crops in Ghana, Nigeria, and Ethiopia are modeled using the systems analysis software iMODELER and by eliciting factors as well as their interconnections through participatory stakeholder workshops. Furthermore, a generic model was created compiling the country models to identify overarching system dynamics with supporting and hindering factors impacting food security in SSA. Findings from the country models show highly complex value webs, suggesting that the predominant value chain approach may oversimplify actual structures and resource flows in real life settings. However, few interconnections within the value webs link the actors and flows of different crops, contradicting predictions emerging from other research. Results from the generic model allow for a critical reflection on the relation between value web dynamics and food security policy in SSA. Current national and regional policy trends targeting market integration, mechanization, and reduction of post-harvest losses are supported by model results

Physicochemical characteristics and microbiological quality of senescent plantain products

Senescent plantains have relatively very rapid deterioration rate compared to plantains at other ripening stages. In Ghana, they are used for products which are consumed either as a snack or a main meal. This paper presents results of a study conducted in five regions of Ghana to investigate processing of senescent plantain products and evaluate their physicochemical characteristics and microbial quality. Survey data were collected on product types and processing methods. Freshly prepared products obtained from respondents were packaged in Ziploc bags and transported in a clean ice chest to the lab for physicochemical and microbial analyses. Samples were stored in the refrigerator (5°C) prior to analyses. Products made by respondents include Apitsi or Apiti, Bodongo, Akankyie, Ofam, Kumaku, Agbetenya; which were either baked or steamed. There were variations in cooking methods, time, type and quantity of ingredients used to produce these products. The products had relatively high moisture (47.63% − 68.42), appreciable crude fat (0.06% − 9.50%), crude protein (1.66% − 7.87%) contents and were good sources of energy (129.64 kcal/g − 241.19/g). The products were slightly acidic, with pH ranging from 4.53 to 5.38. Aerobic plate count, yeast and mold, coliform and E. coli ranged between <10 to 1.7 × 105 CFU/g; 0 and 3.9 × 105 CFU/g; 0 and 1.5 × 102 CFU/g; and 0 and <10 CFU/g, respectively. The bacteriological quality of samples A to I are more superior than samples J and K. Product standardization is required