Optimization of Drying Parameters for Maximum Nutrient Retention in Cassia auriculata: Implications for Functional Food Development

Yam is an important food crop in Ghana. It is a delicacy that is eaten after cooking or frying the fresh sample when cut into slices. The powders of the dried yam can be incorporated into soups, baby food and bread as composite flours. However, the high moisture content of yam when harvested (about 70%wb) makes it susceptible to spoilage leading to reduced shelf life and onward rejection by the consumer. This adds to the waste basket. Drying is a worldwide postharvest method for extending the shelf life of agricultural food products such as yam. An energy source that is cheap and clean has always been from the sun. The open sun method has been utilized severally and for many years, but this is subject to various contaminants and thus reducing its quality. A confined solar drying method is a better option but the energy source is limited to the day’s solar energy. Solar adsorption drying is an opportunity to dry day and night in an efficient and product conserving manner with a reduced drying cycle. Prior to this thesis work, several aspects were insufficiently known to really judge the potential. The thesis tackles some of the bottlenecks and problems: lack of knowledge about the drying properties of yam; how to design appropriate solar collectors for drying and regeneration and to share experiences with the actual implementation of the system to see its possibilities an opportunities. In this thesis the sorption properties of yam which gives an indication of the equilibrium moisture content in relation to water activity at constant temperature, but has been given less attention in literature, is studied. The analytical Crank solution to the Fick’s second law has been utilized in the prediction of drying curves of many food products. However the Crank solution puts limitations on the extent to which the equation could be utilized. The limitation is that the particle of food sample to be dried must be infinite, shrinkage should not exist, while moisture diffusion coefficient must be constant. In practice, these limitations are not realistic since most biological food products go through shrinkage together with variable moisture diffusion. Meanwhile the source of energy for drying has largely come from the sun and has led the use of the so-called open sun drying (OSD) method especially in tropical countries, for so many years. This method exposes the food to weather conditions and contaminants reducing the quality of the dried product. Recent research has shown that a confined drying system is most appropriate in terms of reduced drying time and quality of the final product. The shortcoming of the solar drying (SD) method is that, drying is limited to a time interval of 6-9 hours of the day after which the sun’s energy can no more be explored. Solar adsorption drying (SAD), as an alternative drying to solar drying, is an integrated drying method that helps in drying day and night in a continuous manner. Research in solar adsorption drying systems is limited in literature, therefore its performance is yet to be explored. Solar collectors are an integral part of solar and solar adsorption dryers. However, most researchers construct collectors to see what happens or use heuristic rules, whereas others do not link to dryers. The output air temperature has an effect on the quality of the dried food product, therefore much attention must be given to the output temperature of the air that enters the dryer. On the other hand after adsorption drying, the adsorbent needs to be regenerated. The easiest way to regenerate the adsorbent (silica gel), which requires temperatures over 70°C is by conventional ovens, which is costly. In this thesis, the condition and requirements for solar adsorption drying of yam (Dioscorea rotundata) is investigated. The approach is first to investigate the sorption properties of yam, then the drying characteristics of yam by modifying the Crank solution of the Fick’s diffusion equation, subsequently the model based design and construction of solar collectors for drying and regeneration purposes, and then finally, the proof of principle of solar - adsorption for both drying and regeneration. The first part of this thesis concerns investigating the equilibrium moisture isotherms for yam at 25°C and 50°C, both for sorption and desorption, experimentally using the gravimetric method. The strength of this work is that a Dynamic Vapour Sorption (DVS) analyzer, which is very sensitive to micro changes in weight loss during dehydration or rehydration, was used. A graphical presentation of equilibrium moisture content, as a function of water activity from the outcome of nonlinear regression analyses of desorption and adsorption isotherms respectively, is shown. The findings contradict most of the findings in literature. The parameters and their uncertainty range for each of the models (GAB, Henderson, Halsey, Oswin, Smith, BET and Peleg) are estimated. The strength of the statistical analysis is that an objective criteria is used to select the model that best describes the experimental desorption and adsorption isotherms over the relevant range of moisture contents. This has been presented in a table form where statiscally, the standard error (SE), the percent average relative deviation (PRD), Akaike Information Criterion (AIC), coefficient of performance (R2), and most importantly, the 2-σ bound confidence interval of the parameters, in particular those that bear the same unit as the equilibrium moisture content (Xe), have been taken into consideration. The GAB model was selected to describe both the desorption and adsorption isotherms, because it allows a physical interpretation. Next, Crank’s analytical approximation to Fick’s diffusion equation is used to investigate the effect of moisture dependent sample thickness and diffusivity on the drying behavior of yam (Dioscoreaceae rotundata) cubicles. Separate experiments of drying and shrinkage at constant temperatures of 30, 40 and 50oC were conducted in a cabinet dryer. The comparative study shows an interdependence between diffusivity and shrinkage due to water loss during drying. The analytical expression for the diffusion in a slab results in non-Fickian behavior for smaller cubicles and consequently, results in a higher effective diffusion coefficient. The drying rate trajectory shows two stages as a function of moisture ratio. The drying behavior of yam is better described by observing both drying and drying rate curves concurrently. This gives good agreement between observed and model data by a combination of fractal moisture dependent shrinkage and moisture dependent diffusion. The advantage of this modified Crank’s approximation is that the moisture trajectory of finite food cubicles can be predicted appropriately. Coupled partial differential equations are developed to investigate which collector lengths are appropriate for drying and for adsorbent regeneration. The output air temperature of the model was validated with an experiment. The spatially distributed model is a powerful tool to aid in multi-purpose collector design leading to solar dryer and regeneration system construction. The advantage of this model is that, the spatial mean temperature of the absorber plate, a requirement for the determination of the overall heat loss coefficient, which hitherto is absent in the approach of Duffie and Beckmann, is no more a problem. The result shows a spatially distribution of temperature in air, absorber plate, and glass cover as functions of collector length and time (day) at constant air velocity and presented in a graphical from. While the temperature of absorber plate, glass cover and air are functions of time (day), the air temperature additionally varies directly with collector length. The study shows the operational overall heat loss coefficient, radiative and convective heat gain and efficiency as functions of the operational air velocity. There was a good agreement between the observed and the model air output temperature. The proof of principle of solar adsorption drying (SAD) and its benefits, compared to solar drying (SD) and open sun drying (OSD) and the effects of these drying methods on the quality of different yam cultivars and regeneration of silica gel is considered. The drying methods SAD, SD and OSD are compared in terms of drying cycles. The SAD had, the shortest drying cycle while maintaining the whitish colour of yam, followed by SD and OSD. However, due to the night drying, the SAD dried product is longer exposed to the drying medium (air), leading to slightly lower vitamin C content of dried sample compared to SD dried samples. OSD had the worst effect on vitamin C. The study shows that the different cultivars of yam dried at different rates. Drying has no effect on composition. Regeneration was possible with solar energy but more work must be done to obtain the information needed for improved designs and operation strategies for the desorption. Finally the perspective, impact and the potential application of the study has also been discussed.

This experiment was conducted to examine the influence of drying methods on the essential oil of chamomile (Matricaria chamomilla L.) and its chemical composition. Chamomile flower heads were dried using five different methods: sunlight for 72 h; shade for 1 week; oven at 40 °C for 72 h; solar dryer for 72 h; and microwave for 5 min. Drying methods had slight and nonsignificant impacts on dry biomass of flower heads. The highest percentages of oil in flowers (0.35–0.50%) were observed after solar-drying methods, and the lowest percentage of oil was found after microwave drying (0.24–0.33%). Drying methods significantly influenced the number of identified compounds. The maximum was identified after solar drying (21 compounds), while the lowest was identified after microwave drying (13 compounds), which revealed the solar ability to preserve compounds in contrast to microwave, which crushed the compounds. Major compounds were α-bisabolol oxide A (33.0–50.5%), (Z)-tonghaosu (10.0–18.7%), α-bisabolol oxide B (8.2–15.4%), α-bisabolone oxide A (5.4–14.6%), and chamazulene (1.9–5.2%) of essential oil. Drying methods clearly affected major compounds’ content as the lowest α-bisabolol oxide A was after sun drying, and the lowest α-bisabolol oxide B was after solar drying. (Z)-tonghaosu increased during drying compared to fresh flowers. Solar drying maintained higher chamazulene content (3.0%) compared to other drying methods. The results of this study suggest that drying under the shady conditions preserved chemical composition of essential oil with higher α-bisabolol content compared to other drying methods.

Sarpagandha (Rauwolfia serpentina) root of Grade 1 (G1) and grade 2 (G2) of 6, 12 and 18 months maturity stages were dried using four different drying methods viz. sun drying (SD), shade drying (SHD), solar drying (SLD) and hot air drying (HAD 50°C, HAD 60°C, HAD 70°C). Drying characteristics for different drying methods, root grade and maturity stage have been explored and their influence on moisture ratio versus drying time was assessed using an ANN model. The phytochemicals such as total phenolic content (TPC), flavonoid, ascorbic acid and tannin as well as the antioxidant activity of all the dried samples have been evaluated. Drying time requirement for sarpagandha roots to achieve final moisture content of about 4.0 to 6.95% d.b. varied between 150–750 mins for HAD and 4–15 days for traditional drying (SD, SHD, SLD) methods also Grade 1 samples took more time than grade 2 samples irrespective of drying methods and maturity stage. The ANN model using logsig and transig transfer functions could best predict the moisture ratio vs drying time (R2=0.999) for HAD and (R2=0.995) for traditional ­methods respectively. The study revealed that the samples of 18 months maturity possessed maximum amount of all the bioactive compounds and antioxidant activities. Among the hot air drying, the samples dried at 60°C and among the traditional methods, the shade dried samples could retain significantly higher amount of most of the phytochemicals and antioxidant properties.

This study investigated the impact of various processing methods sun drying, dehydration, frying and cooking) on nutritional and phytochemical profile of wild melon (Cucumis melo var. agrestis). Proximate analysis revealed that drying methods enhanced the concentration of essential nutrients, including carbohydrates, proteins, and fibre, due to moisture reduction. Frying led to an increase in fat content but reduced specific heat-sensitive vitamins and antioxidants. Cooking resulted in varying phytochemical changes, with some compounds degrading while others became more bioavailable. Notably, sun drying and dehydration preserved higher levels of phenolic compounds and flavonoids, enhancing the antioxidant potential of wild melon. These findings highlight the impact of processing on nutrient retention and phytochemical stability, underscoring the need for optimized techniques to maximize its nutritional benefits. Further research is recommended to assess these nutrients' bioavailability and functional health benefits. Practical Application: Through a systematic examination of different processing methods, the research provides novel insights into how these methods influence the melon's nutritional composition and phytochemistry. The findings demonstrate that sun-drying optimizes proximate composition, while thermal drying enhances mineral composition. Additionally, the study highlights the preservation of bioactive compounds in fresh samples and the concentration of organic acids in dried samples. This work advances the field of food science by offering a foundation for optimizing processing methods to enhance traditional foods' nutritional and phytochemical profiles, with significant implications for food fortification, preservation, and security.

BackgroundAccurately targeting the nutritional needs of the early preterm infant is challenging when human milk is used due to the natural variation in energy composition. The purpose of this study was to develop and evaluate a simple method for reducing the variation in fat and energy content of human milk prior to fortification such that the infant receives a diet of known composition.MethodsMilk was centrifuged at low speed to concentrate the fat into a cream layer and a predetermined volume of skim milk is removed to meet a specific fat concentration. The fat layer is then resuspended to produce reconstituted milk of a specified standard fat content.ResultsUsing this method it was possible to reduce the coefficient of variation in fat content of six different samples of donor human milk from 19.3% to 2.6%. As fat globule size may be associated with fat absorption, the effect that centrifugation and resuspension had on human milk fat globule distribution was assessed by laser diffraction particle sizing. No difference in the particle distribution of the treated and untreated human milk was observed.ConclusionThis method is accurate and simple, allowing for integration alongside current milk bank and NICU practices for use with both donor human milk and mother's own milk.

In the present study, combination of Teff flour and powdered guava leaf was utilized to develop composite flour mixes. Effect of two different drying techniques of hot air oven and solar drying was assessed on the guava leaves for the composition. The composite flour mixes were evaluated for physical, nutritional, mineral, anti-nutritional, phenolic and antioxidant components. Among the physical properties, the bulk density, tapped density, Carr index, Hausner ratio, water absorption capacity, swelling index, foaming capacity and water solubility index were evaluated. Protein was found to be highest in Teff flour (13.41 g/100 g) and among the combination of composite flours it ranged between 12.19 to 12.89 g/100 g. Whereas, the total dietary fiber among the composite flours was found to be between 4.18 to 5.04 g/100 g. The anti-nutrients of phytic acid and total tannin content among the analyzed samples was ranging from 0.48 to 0.66 g/100 g and 1.40 to 3.40 mg CE/g, respectively. The Fe and Zn content among the analyzed samples were ranging between 8.01 to 10.99 and 0.69 to 3.56 mg/100 g, respectively. Among the analyzed samples, the highest total phenolic content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC), and total carotenoid content (TCC) was found in solar dried guava leaf (SGL) sample with 18.99 g GAE/100 g, 5.36 g CE/100 g, 1.48 mg/g, and 20.96 mg/100 g, respectively. Concurrently the highest antioxidant activity assessed by DPPH, ABTS and FRAP assay methods was also found in SGL sample with 94.59% inhibition, 98.10% inhibition and 6.01 M Fe+/g, respectively. Solar drying method retained higher nutritional and phenolic components in comparison to the hot air oven drying method. In the present study, the composite flour combinations containing Teff flour and guava leaf powder provided optimum nutrients and bioaccessibility of minerals. Also, incorporation of guava leaf powder increased the phenolic components and the antioxidant activity of the formulated products.

Bombax buonopozense is one of the underutilized plants in West African. Most of the parts of this plant are used by some populace in West Africa for medicinal and nutritional purposes while the sepals mostly go waste. The objective of this study is to evaluate the effect of different drying methods on some nutritional and anti- nutritional composition of fresh and dried sepals of B. buonopozense. The sepals were oven, solar and sun dried while the fresh sepals served as a control. Proximate, some mineral and anti- nutrient composition of the sepals were determined. The fresh samples were significantly different from all the dried samples (p<0.05). Ash content was relatively high with a range of 7.38 to 7.86%; protein, 9.99 to 10.76%; crude fiber, 14.63 to 15.39%; carbohydrate, 56.62 to 63.52%; iron, 1.55 to 3.22 mg/100 g; magnesium, 171.92 to 184.47 mg/100 g for the dried sepals. The various drying methods reduced the content of both oxalate and phytate of the sepals. The present findings show that drying of sepals of B. buonopozense tends to retain most of the nutrients as well as reduction in the anti- nutrients. Hence the dried sepals could be used as a potential ingredient in making foods such as soups and sauces. Key words: Bombax buonopozense, antinutrients, drying methods, nutritional composition.

Morphometric estimates of body condition are widely used by ornithologists, but which estimates work best is a matter of debate. We review morphometric approaches (body mass, ratio and residual condition indices, predictive regression models, fat scoring, and abdominal profiles) for estimating body condition (defined as fat mass) in birds. We describe the strengths and weaknesses of each approach. Across diverse indices and species (~200 estimates total), the mean r 2 relating condition indices to mass of body fat was 0.55, and 64% of the r 2 values were greater than 0.50. But despite their generally good performance, condition indices sometimes perform poorly (i.e., r 2 is low). The data indicate that: (1) no single index was clearly best, (2) on average body mass alone, fat scores, and predictive multiple regression equations explained slightly more than 50% of the variation in fat content, (3) on average, ratio and residual indices explained slightly less than 50% of the variation in fat content, and (4) body mass alone, a variable that can be easily and reliably measured, is as good or nearly as good an indicator of fat content as any other condition index. We recommend that: (1) morphometric indicators of condition be empirically validated, (2) researchers publish their body composition data in sufficient detail that they can be used in future analyses exploring the relative merits of different condition indices, and (3) multiple regression directly on measured traits be used instead of condition indices whenever the condition index is not empirically validated.

The effect of plane of nutrition on the carcasses of pigs and lambs when variations in fat content are excluded

This study presents the effects of different drying methods on the proximate composition and energy value of green plantain flour, using the oven, sun and solar dryer as a drying medium. The green plantain samples were peeled, sliced and dried for 18 h at 60 ◦C using laboratory oven; 45 h for sun-drying and 24 h using solar dryer. Results of the proximate analysis obtained show that moisture contents for oven, sun and solar dried samples were; 2.7%, 3.15% and 3.42%, respectively. There was a significant difference (p&lt;0.05) in the moisture contents of the samples, with a p-value of 0.021. Ash contents were 3.94% for oven dried sample, 4.21% for sun dried sample and 4.33% for solar dryer. There was no significant difference in the ash contents of the samples (p&gt;0.05), with a p-value of 0.090.Fibre contents were 2.89%, 3.11% and 3.07% for oven dried, sun dried, solar dryer samples, respectively. Protein contents were; 3.85% for oven dried sample, 4.66% for sun dried sample and 4.68% for solar dryer. Protein content was significantly lowest in the oven-dried sample compared to other samples (p =0.065). Lipid contents were 2.51%, 2.37% and 2.26% for oven dried, sun-dried and solar dryer, respectively. The three drying methods non-significantly (p&gt;0.05) affected the lipid contents of the samples. Carbohydrate contents were 87.81% for the oven dried sample, 85.58% for the sun dried sample and 85.66% for the solar dryer, and there was no significant effect (p&gt;0.05) on the carbohydrate contents of the samples. Caloric values were 385.23 kcal, 380.29 kcal and 381.70 kcal for oven dried, sun dried and solar dryer, respectively. There was no significant effect (p&gt;0.05) on the caloric (energy) value of the samples. The results of this study suggest that different drying methods have varied effects on the proximate composition and energy value of green plantain.

Solar drying of medicinal herbs: A review

Many studies have revealed the susceptibility of long grain rice to breaking during milling, while others have demonstrated the variation in the yield of head rice due to different rough rice drying methods. Thus, this study aims to determine appropriate drying and milling methods to improve the head rice yield and nutritional quality of long grain rice. A series of drying experiments were performed on rough paddy rice employing shallow bed, oven and sun drying methods. Then, the dried rough rice grains were milled with various dehusking (H), separation (S) and polishing (P) configurations to obtain white rice. The resulting batches of white rice were analyzed and compared in terms of head rice yield, broken rice yield, brewer yield, whiteness and nutritional quality. Milling configurations strongly affected the total, head rice, broken rice and brewer yields. The configuration of one dehusking, one separation and one polishing (H &ndash; S &ndash; P) resulted in the highest milling and head rice yields. Although the whiteness of the rice samples was significantly affected by the milling configuration, their values fell within an acceptable range preferred by consumers in Southeast Asia (39&ndash;47). The milling of dried rough rice obtained from shallow bed and sun drying using a concrete floor and white tarpaulin resulted in a comparable total (65%) and head rice yield (51%). However, the milling of rough rice dried using an oven and sun drying on black tarpaulin resulted in a slightly lower total yield (64.50%) and head rice yield (50.50%). The moisture, ash, protein and lipid contents of the white rice were significantly lower than those of manually dehulled rice, whereas the carbohydrate and amylose contents of the white rice were significantly higher. Application of shallow bed or sun drying on a concrete floor followed by milling with the H &ndash; S &ndash; P configuration produced the highest head rice yield with an acceptable whiteness and nutritional composition. These combined postharvest technologies are simple, efficient and economical for both small- and large-scale applications. Further research on consumer acceptance and on the nutritional and cooking qualities of the white rice obtained from these combined postharvest technologies is essential.

This work was carried up in the objective to valorize the broad beans, largely harvested in Algeria, by solar drying means. In the present research paper, an experimental study was conducted on solar drying of broad beans by two different methods. Experimental trials were performed on a direct and an indirect laboratory scale solar dryers at Ouargla university in the southern of Algeria. Selected samples were dried at 50°C, 55°C, 60°C and 65°C. In both two applied cases, drying curves were obtained and compared. Among twelve consulted drying models the Page model was correlated with satisfaction to describe the solar drying of broad beans using a non linear regression analysis method. Operating and thermal performances of the two used drying systems were checked by the energy effeceincy and economic calculation. Obtained results showed that the direct solar drying ensures good preservation of the final product with a drying time of 5 hours. Keywords: solar drying ; convective drying ; broad bean ; quality

A significant level of intergroup differentiation and specificity of cows with different proportions of conditional blood by Holstein breed on the basis of milk productivity was revealed. There is a tendency of some increase in milk yield of cows with an increase in their conditional blood content by Holstein breed over 50% and above and a decrease in milk fat content by 0.16%. Our research has established quite significant recurrence rates for the considered signs of milk productivity at the highest degrees of probability, which indicates the possibility of effective selection of cows on the basis of milk productivity for the first lactation. Age-related recurrence of signs of milking between the first and higher lactation is higher than the same in terms of fat content in milk. At the same time, there is a clear trend of a gradual increase in the coefficients of recurrence of both quantitative and qualitative composition of the milk of cows of the herd with an increase in their conditional blood content by Holstein breed. The only exceptions are low-blooded animals (up to 50%). One-factor analysis of variance revealed a very insignificant and unreliable effect of heredity by Holstein breed on the hopes of cows for both the first and higher lactation. The influence of conditional blood by Holstein breed on the variability of fat content in milk is slightly higher (11–15%) at the highest levels of reliability. Correlation analysis of signs of milk yield and fat content in milk for both the first and higher lactation revealed mostly low values of correlation coefficients with a predominantly low degree of reliability. There was some increase in the correlation and change of its direction from negative to positive in high-blooded Holstein animals. Significant variability of coefficients of phenotypic consolidation of cows of different conditional bloodlines by Holstein breed on the main signs of milk productivity is noted. There is a tendency to reduce the coefficients of phenotypic consolidation of signs of milk productivity, in addition to the fat content in milk, with an increase in conditional blood in Holstein breed to 75% and above and in low-blooded animals (up to 50%).

The effect of milk fat content on ohmic heating compared to conventional heating for inactivation of food-borne pathogens was investigated. Sterile cream was mixed with sterile buffered peptone water and adjusted to 0, 3, 7, 10% (w/v) milk fat content. These samples with varying fat content were subjected to ohmic and conventional heating. The effect of milk fat on temperature increase and electrical conductivity were investigated. Also, the protective effect of milk fat on the inactivation of foodborne pathogens was studied. For conventional heating, temperatures of samples increased with time and were not significantly (P > 0.05) different regardless of fat content. Although the inactivation rate of Escherichia coli O157:H7, Salmonella Typhimurium and L. monocytogens decreased in samples of 10% fat content, a protective effect was not observed for conventional heating. In contrast with conventional heating, ohmic heating was significantly affected by milk fat content. Temperature increased more rapidly with lower fat content for ohmic heating due to higher electrical conductivity. Nonuniform heat generation of nonhomogeneous fat-containing samples was verified using a thermal infrared camera. Also, the protective effect of milk fat on E. coli O157:H7 and Listeria monocytogenes was observed in samples subjected to ohmic heating. These results indicate that food-borne pathogens can survive in nonhomogeneous fat-containing foods subjected to ohmic heating. Therefore, more attention is needed regarding ohmic heating than conventional heating for pasteurizing fat-containing foods. The importance of adequate pasteurization for high milk fat containing foods was identified.