Comparison between freeze and spray drying to obtain powder Rubrivivax gelatinosus biomass

The use of colorants in products of animal origin is justified by the improvement in the color of foods since this attribute is considered a quality criterion. These additives can be produced using industrial effluents as substrates and appropriate organisms, such as Rubrivivax gelatinosus. Oxycarotenoids represent a class of carotenes responsible for the pigmentation of animals and vegetables. R. gelatinosus grows in fish industry effluent with the resulting production of a bacterial biomass containing oxycarotenoids. The purpose of this study was to compare the use of two drying processes - spray and freeze drying - to obtain powder biomass in terms of the process parameters (yield, productivity, and product recovery) and the product characteristics (color, proximate composition, and oxycarotenoids). No difference was detected in the yield between these techniques, while productivity was higher using spray drying. Higher product recovery and moisture were achieved with freeze drying, while ash was higher with spray drying. The freeze dried biomass was redder, darker and less saturated than the spray dried biomass. No difference in oxycarotenoids was detected between the biomasses. Although it results in lower recovery rate, spray drying was faster and more productive, and it provided the same yield as freeze drying, which makes it the method of choice for obtaining R. gelatinosus biomass.

Marolo (Annona crassiflora Mart.): a study of value chain and processing

This article aims to discuss the needs and problems of marolo value chain, as well as to evaluate the rehydration process of this fruit as a possibility of using it as a by-product during the interharvest growth periods. The study of the value chain included interviews with producers, handlers, and fruit and by-product sellers. In order to evaluate the rehydration process of this fruit, marolo was dehydrated using a conventional procedure and freeze-drying. The experiments were conducted in a completely randomized design and a triple factorial scheme (2 × 2 × 6). ANOVA was performed, followed by the Tukey's test (p < 0.05). Regression models were generated and adjusted for the time factor. The precariousness of the value chain of marolo was observed. The best procedure for marolo dehydration should be determined according to the intended use of the dehydrated product since the water-absorption capacity of the flour is higher and convective hot-air-drying is more effective in retaining soluble solids and reducing damage to the fruit. These results aim at contributing to the marolo value chain and to the preservation of native trees in the Brazilian savanna biome and can be used to analyze other underutilized crops.

An artificial neural network model for prediction of quality characteristics of apples during convective dehydration

In this study, the effects of hot-air drying conditions on color, water holding capacity, and total phenolic content of dried apple were investigated using artificial neural network as an intelligent modeling system. After that, a genetic algorithm was used to optimize the drying conditions. Apples were dried at different temperatures (40, 60, and 80 °C) and at three air flow-rates (0.5, 1, and 1.5 m/s). Applying the leave-one-out cross validation methodology, simulated and experimental data were in good agreement presenting an error < 2.4 %. Quality index optimal values were found at 62.9 °C and 1.0 m/s using genetic algorithm.

Quality characteristics of Moroccan sweet paprika (Capsicum annuum L.) at different sampling times

"La Niora" is a red pepper variety cultivated in Tadla Region (Morocco) which is used for manufacturing paprika after sun drying. The paprika quality (nutritional, chemical and microbiological) was evaluated immediately after milling, from September to December. Sampling time mainly affected paprika color and the total capsaicinoid and vitamin C contents. The commercial quality was acceptable and no aflatoxins were found, but the microbial load sometimes exceeded permitted levels.

Microencapsulation of babassu coconut milk

The objective of this study was to obtain babassu coconut milk powder microencapsulated by spray drying process using gum Arabic as wall material. Coconut milk was extracted by babassu peeling, grinding (with two parts of water), and vacuum filtration. The milk was pasteurized at 85 ºC for 15 minutes and homogenized to break up the fat globules, rendering the milk a uniform consistency. A central composite rotatable design with a range of independent variables was used: inlet air temperature in the dryer (170-220 ºC) and gum Arabic concentration (10-20%, w/w) on the responses: moisture content (0.52-2.39%), hygroscopicity (6.98-9.86 g adsorbed water/100g solids), water activity (0.14-0.58), lipid oxidation (0.012-0.064 meq peroxide/kg oil), and process yield (20.33-30.19%). All variables influenced significantly the responses evaluated. Microencapsulation was optimized for maximum process yield and minimal lipid oxidation. The coconut milk powder obtained at optimum conditions was characterized in terms of morphology, particle size distribution, bulk and absolute density, porosity, and wettability.

Evaluation of the influence of seasonality and landscape on the physicochemical characteristics of propolis

This study aimed at verifying the influence of the seasonality and landscape of the place of apiaries in the production and physicochemical quality of propolis produced in Cáceres-MT. Within August/2006 and July/2007 twenty-three propolis samples were collected monthly. The physicochemical quality of propolis was determined by the characteristic: loss by drying, wax, mechanical mass, oxidation activity, dry extract, flavonoids and total phenolics. The production of propolis was analyzed through correlation with seasonality (dry and wet). The same statistic model was used to correlate the production with the landscape (highland and flood plain). For each physicochemical characteristic were used statistic model of correlation described for the production of propolis. The seasonality did not influence on propolis production and on physicochemical quality. The landscape did not influence on propolis production and physicochemical quality loss by drying and mechanical mass, however, it determined the physicochemical quality for wax (x=22.44%), oxidation activity (x=9.73''), dry extract (x=22.31%), flavonoids (x=1.94%) and total phenolics (x=0.02%) in the highland of the Pantanal of Cáceres. This way it concludes that the production and physicochemical quality of propolis were not influenced by seasonality. The landscape influenced positively on physicochemical quality of propolis in the highland of the Pantanal of Cáceres.

Dehydration of "dedo de moça" pepper: kinetics and phytochemical concentration

Red pepper is rich in vitamin C and other phytochemicals and can be consumed as a dehydrated product. The evaluation of the best drying conditions can ensure a better quality product. This study aimed to investigate the effect of air temperature (55, 65, and 75 ºC) on drying kinetics of red peppers and on vitamin C, total phenolic content, and color of dried pepper as compared to the fresh product. Dehydration was carried out in a forced convection oven. Drying kinetics was determined by periodic weighting until constant weight. The moisture content of the fresh pepper was approximately 86%. The drying curves were fitted to three different models available in the literature. The Page model showed the best fit for this process. Analysis of variance revealed that the air drying temperature significantly influenced (p < 0.05) the quality parameters (vitamin C content, total phenolic content, and color) of the dried pepper as compared to the fresh pepper. After drying, the vitamin C retention increased with reduced air-drying temperature. In general, products dried at lower temperatures exhibited better quality due to reduced losses of bioactive compounds.

Mathematical modeling of microwave dried celery leaves and determination of the effective moisture diffusivities and activation energy

Celery (Apium graveolens L. var. secalinum Alef) leaves with 50±0.07 g weight and 91.75±0.15% humidity (~11.21 db) were dried using 8 different microwave power densities ranging between 1.8-20 W g-1, until the humidity fell down to 8.95±0.23% (~0.1 db). Microwave drying processes were completed between 5.5 and 77 min depending on the microwave power densities. In this study, measured values were compared with predicted values obtained from twenty thin layer drying theoretical, semi-empirical and empirical equations with a new thin layer drying equation. Within applied microwave power density; models whose coefficient and correlation (R²) values are highest were chosen as the best models. Weibull distribution model gave the most suitable predictions at all power density. At increasing microwave power densities, the effective moisture diffusivity values ranged from 1.595 10-10 to 6.377 10-12 m2 s-1. The activation energy was calculated using an exponential expression based on Arrhenius equation. The linear relationship between the drying rate constant and effective moisture diffusivity gave the best fit.

Multivariate study of Nile tilapia byproducts enriched with omega-3 and dried with different methods

Abstract The present work aimed at studying the effect of different drying methods applied to tilapia byproducts (heads, viscera and carcasses) fed with flaxseed, verifying the contents of omega-3 fatty acids. Two diets were given to the tilapia: a control and a flaxseed formulation, over the course of 60 days. After this period, they were slaughtered and their byproducts (heads, viscera and carcasses) were collected. These fish parts were analyzed in natura, lyophilized and oven dried. Byproducts from tilapia fed with flaxseed presented docosapentaenoic, eicopentaenoic and docosahexanoic fatty acids as a result of the enzymatic metabolism of the fish. The byproducts from the oven drying process had lower levels of polyunsaturated fatty acids. In the multivariate analysis, the byproducts from fish fed with flaxseed had a greater composition of fatty acids. The addition of flaxseed in fish diets, as well as the utilization of their byproducts, may become a good business strategy. Additionally, the byproducts may be dried to facilitate transport and storage.

Microbiological and sensory evaluation of Jambu (Acmella oleracea L.) dried by cold air circulation

Abstract The aim of this study was to evaluate the microbiological and sensory quality of the Jambu (Acmella oleracea L.) in natura and dried by cold air, and the determination of its drying curve. The microbiological analysis were performed to Salmonella spp, the coagulase-positive Staphylococcus, and coliforms in the both Jambu samples, at 45 °C. Tacacá, the typical food dish of Pará state, Brazil, has showed good consumer global acceptance in the sensory evaluation of Jambu in natura (score of 8.00 ± 1.46) and dried (score of 8.67 ± 0.66). Both samples, Jambu in natura and dried by cold air, were by the current legislation regarding the microbiological aspects, this is the absence of Salmonella spp, coagulase-positive Staphylococcus <1×101 CFU/g, and coliforms <3 MPN/g, at 45 °C. Thus, considering sensory and health aspects, the commercialization of dried Jambu becomes viable, facilitating its transportation and handling, as well as for reducing its vegetable mass.

Action of gibberellic acid (GA3) on dormancy and activity of alpha-amylase in rice seeds

To evaluate the effectiveness of gibberellic acid (GA3) in breaking rice seed dormancy and the use of alpha-amylase enzyme activity as an indicator of the dormancy level, seed from the intensively dormant irrigated cultivar Urucuia were used. The seeds were submitted to a pre-drying process in a forced air circulation chamber under 40ºC during 7 days and submersed in 30 mL of GA3 solution under 0, 10, 30 and 60 mg/L H2O concentrations, during 2, 24 and 36 hours. After the treatments, the alpha-amylase activity was determined by using the polyacrilamide electrophoresis and spectrophotometry. At the same time, the germination test was made. The results indicated a gain in germination and in alpha-amylase activity in higher concentrations and soaking time of seeds in GA3. These observations support the conclusion that soaking seed in 60 mg GA3/L during 36 hours can be used as a quick and efficient treatment in breaking rice seed dormancy and is equivalent to the forced air circulation chamber at 40ºC during 7 days. The alpha-amylase enzyme activity proved to be as an efficient marker of the seeds dormancy level.

Drying soybean seed using air ambient temperature at low relative humidity

Under subtropical and tropical environments soybean seed (Glycine max (L.) Merrill) are harvested early to avoid deterioration from weathering. Careful after-harvest drying is required and is an important step in maintaining the physiological quality of the seed. Soybean seed should be harvested when the moisture content is in a range of 16-20%. Traditional drying utilizes a high temperature air stream passed through the seed mass without dehumidification. The drying time is long because the system is inefficient and the high temperature increases the risk of thermal damage to the seed. New technology identified as heat pipe technology (HPT) is available and has the unique feature of removing the moisture from the air stream before it is passed through the seed mass at the same environmental temperature. Two studies were conducted to evaluate the performance of HPT for dry soybean seed. In the first study the seeds were dried from 17.5 to 11.1% in 2 hours and 29 minutes and in the second sudy the seeds were dried from 22.6 to 11.9% in 16 hours and 32 minutes. This drying process caused no reduction in seed quality as measured by the standard germination, tetrazolium-viability, accelerated aging and seedling vigor classification tests. The only parameter that indicated a slight seed quality reduction was tetrazolium vigor in the second study. It was concluded that the HPT system is a promising technology for drying soybean seed when efficiency and maintenance of physiological quality are desired.

Drying peanut seed using air ambient temperature at low relative humidity

The moisture content of peanut kernel (Arachis hypogaea L.) at digging ranges from 30 to 50% on a wet basis (w.b.). The seed moisture content must be reduced to 10.5% or below before seeds can be graded and marketed. After digging, peanuts are cured on a window sill for two to five days then mechanically separated from the vine. Heated air is used to further dry the peanuts from approximately 18 to 10% moisture content w.b. Drying is required to maintain peanut seed and grain quality. Traditional dryers pass a high temperature and high humidity air stream through the seed mass. The drying time is long because the system is inefficient and the high temperature increases the risk of thermal damage to the kernels. New technology identified as heat pipe technology (HPT) is available and has the unique feature of removing the moisture from the air stream before it is heated and passed through the seed. A study was conducted to evaluate the performance of the HPT system in drying peanut seed. The seeds inside the shells were dried from 17.4 to 7.3% in 14 hours and 11 minutes, with a rate of moisture removal of 0.71% mc per hour. This drying process caused no reduction in seed quality as measured by the standard germination, accelerated ageing and field emergence tests. It was concluded that the HPT system is a promising technology for drying peanut seed when efficiency and maintenance of physiological quality are desired.

Characterisation of Cladonia rangiferina transcriptome and genome, and the effects of dehydration and rehydration on its gene expression

Lichens are symbiotic organisms, which consist of the fungal partner and the photosynthetic partner, which can be either an alga or a cyanobacterium. In some lichen species the symbiosis is tripartite, where the relationship includes both an alga and a cyanobacterium alongside the primary symbiont, fungus. The lichen symbiosis is an evolutionarily old adaptation to life on land and many extant fungal species have evolved from lichenised ancestors. Lichens inhabit a wide range of habitats and are capable of living in harsh environments and on nutrient poor substrates, such as bare rocks, often enduring frequent cycles of drying and wetting. Most lichen species are desiccation tolerant, and they can survive long periods of dehydration, but can rapidly resume photosynthesis upon rehydration. The molecular mechanisms behind lichen desiccation tolerance are still largely uncharacterised and little information is available for any lichen species at the genomic or transcriptomic level. The emergence of the high-throughput next generation sequencing (NGS) technologies and the subsequent decrease in the cost of sequencing new genomes and transcriptomes has enabled non-model organism research on the whole genome level. In this doctoral work the transcriptome and genome of the grey reindeer lichen, Cladonia rangiferina, were sequenced, de novo assembled and characterised using NGS and traditional expressed sequence tag (EST) technologies. RNA extraction methods were optimised to improve the yield and quality of RNA extracted from lichen tissue. The effects of rehydration and desiccation on C. rangiferina gene expression on whole transcriptome level were studied and the most differentially expressed genes were identified. The secondary metabolites present in C. rangiferina decreased the quality – integrity, optical characteristics and utility for sensitive molecular biological applications – of the extracted RNA requiring an optimised RNA extraction method for isolating sufficient quantities of high-quality RNA from lichen tissue in a time- and cost-efficient manner. The de novo assembly of the transcriptome of C. rangiferina was used to produce a set of contiguous unigene sequences that were used to investigate the biological functions and pathways active in a hydrated lichen thallus. The de novo assembly of the genome yielded an assembly containing mostly genes derived from the fungal partner. The assembly was of sufficient quality, in size similar to other lichen-forming fungal genomes and included most of the core eukaryotic genes. Differences in gene expression were detected in all studied stages of desiccation and rehydration, but the largest changes occurred during the early stages of rehydration. The most differentially expressed genes did not have any annotations, making them potentially lichen-specific genes, but several genes known to participate in environmental stress tolerance in other organisms were also identified as differentially expressed.

Osmotic priming methodologies in relation to the physiological performance of rangpur lime seeds (Citrus limonia Osbeck)

Several mechanisms have been used to promote rapid germination of citrus seeds and uniform seedling emergence. We evaluated the effects of osmotic priming on the physiological performance of Rangpur lime seeds (Citrus limonia Osbeck). Seeds were treated with 30 g of Captan and 10 g of Tecto 600 in 20-litre batches and stored, without drying, at 10 ºC and 50% relative humidity for periods of 3, 6 and 9 months. After each period, seeds were primed at 25 ºC, in the light, by immersion in Poliethylenoglicol (PEG 6000), potassium nitrate (KNO3) and 70% PEG 6000 plus 30% KNO3, all at an osmotic potential of -1.1MPa, for priming periods of 3, 6, 9 and 12 days. Percentage germination, tray emergence and the emergence rate index (ERI) were evaluated. Priming in PEG 6000 solution, independent of priming period, or in KNO3 or PEG 6000 plus KNO3 for up to 9 days, were efficient at improving the physiological performance of seeds stored for up to 3 months. Osmotic priming appears to be a promising technique for improving the physiological quality of Rangpur lemon seeds.