Effect of blanching time on selective mineral elements extraction from the spinach substitute (Tetragonia expansa) commonly used in Brazil

The true spinach (Spinacia oleracea) does not grow well in warm climates and for that reason is not commercialized in Brazil. Instead, a spinach substitute (Tetragonia expansa), originally from New Zealand, is widely used in the country. There is scant information on the mineral profile and none on the soluble mineral fraction of this vegetable. The solubility of a mineral is one of the important factors for its absorption. For this reason, the calcium, magnesium, iron, manganese, copper, zinc, potassium, and sodium soluble fractions in the raw spinach substitute were determined and the effect of blanching times on the solubility of these minerals was investigated. Blanching times of 1, 5, and 15 minutes were employed. The magnesium, manganese, potassium, and sodium soluble fractions increased sizably with shorter blanching time. Longer blanching time (15 minutes) caused large losses of minerals. The soluble mineral fractions can contribute poorly to diet in terms of potassium, magnesium, manganese, and zinc. The spinach substitute cannot be considered a dietary source of calcium, iron and copper due to the insolubility of these minerals in the vegetable, possibly caused by the large oxalate content.

The impact of blanching and high-pressure pretreatments on oil uptake of fried potato slices

The effect of high-pressure (HP) pretreatment on oil uptake of potato slices is examined in this paper. Potato slices were treated either by HP or thermal blanching, or a combination of thermal blanching followed by HP prior to frying. The effect of HP on starch gelatinization and potato microstructure was assessed by differential scanning calorimeter and environmental scanning electron microscope (ESEM), respectively. After treatments, the slices were fried in sunflower oil at 185 °C for a predetermined time. Frying time was either kept constant (4 min) or varied according to the time needed to reach a desired moisture content of ≈2%. The high pressure applied in this study was found not to be sufficient to cause a significant degree of starch gelatinization. Analysis of the ESEM images showed that blanching had a limited effect on cell wall integrity. HP pretreatment was found to increase the oil uptake marginally. When frying for a fixed time, the highest total oil content was found in slices treated at 200 MPa for 5 min. The oil content was found to increase significantly (p<0.05) to 41.23±1.82 compared to 29.03±0.21 in the control slices. The same effect of pressure on oil content was found when the time of frying varied. On the other hand, HP pretreatment was found to decrease the frying time required to achieve a given moisture content. Thus, high-pressure pretreatment may be used to reduce the frying time, but not oil uptake.

High hydrostatic pressure blanching of baby spinach (Spinacia oleracea L.)

Given the high susceptibility of baby spinach leaves to thermal processing, the use of high hydrostatic pressure (HHP) is explored as a non-thermal blanching method. The effects of HHP were compared with thermal blanching by following residual activity of polyphenol oxidases and peroxidases, colour retention, chlorophyll and carotenoids content, antioxidant capacity and total polyphenols content. Spinach subjected to 700 MPa at 20 ºC for 15 min represented the best treatment among the conditions studied due to its balanced effect on target enzymes and quality indices. The latter treatment reduced enzyme activities of polyphenol oxidases and peroxidases by 86.4 and 76.7 %, respectively. Furthermore, leaves did not present changes in colour and an increase by 13.6 % and 15.6 % was found in chlorophyll and carotenoids content, respectively; regarding phytochemical compounds, retentions of 28.2 % of antioxidant capacity and 77.1 % of polyphenols content were found. Results demonstrated that HHP (700 MPa) at room temperature, when compared with thermal treatments, presented better retention of polyphenols, not significantly different chlorophyll and carotenoids content and no perceptible differences in the instrumental colour evaluated through ΔE value; therefore, it can be considered a realistic practical alternative to the widely used thermal blanching.

Evaluation of various pre-treatments for the dehydration of banana and selection of suitable drying models

The thin-layer drying behaviour of bananas in a beat pump dehumidifier dryer was examined. Four pre-treatments (blanching, chilling, freezing and combined blanching and freezing) were applied to the bananas, which were dried at 50 degreesC with an air velocity of 3.1 m s(-1) and with the relative humidity of the inlet air of 10-35%. Three drying models, the simple model, the two-term exponential model and the Page model were examined. All models were evaluated using three statistical measures, correlation coefficient, root means square error, and mean absolute percent error. Moisture diffusivity was calculated based on the diffusion equation for an infinite cylindrical shape using the slope method. The rate of drying was higher for the pre-treatments involving freezing. The sample which was blanched only did not show any improvement in drying rate. In fact, a longer drying time resulted due to water absorption during blanching. There was no change in the rate for the chilled sample compared with the control. While all models closely fitted the drying data, the simple model showed greatest deviation from the experimental results. The two-term exponential model was found to be the best model for describing the drying curves of bananas because its parameters represent better the physical characteristics of the drying process. Moisture diffusivities of bananas were in the range 4.3-13.2 x 10(-10) m(2)s(-1). (C) 2002 Published by Elsevier Science Ltd.

The effect of pretreatments on the drying rate and quality of dried bananas

The effects that four pretreatments (blanching, chilling, freezing, and combined blanching and freezing), used prior to drying, had on the drying rate and quality of bananas were investigated. An untreated sample was used as a control. The bananas were dried at 50 degreesC in a heat pump dehumidifier dryer, using an air velocity of 3.1 m s(-1), until a final moisture content of approximately 25% dry weight basis was attained. While the initial drying rate was highest for the blanched treatment, the two pretreatments involving freezing resulted in the shortest drying times. The blanched sample was most preferred in terms of colour while the frozen samples exhibited extensive browning. The texture and flavour was significantly (P < 0.05) reduced in all samples that involved blanching and/or freezing.

Factores de risco para doenças músculo-esqueléticas não específicas no sector das limpezas em ser

The aim of this paper is to characterize complaints in the upper limbs, shoulders, neck and back- lumbar region directly related to musculo-skeletal disorders in a sampling of 114 cleaners from seven cleaning (janitor) companies, operating at eight client organizations. Complaints had been diagnosed as stiffness, any pain, numbness, paraesthesiae, tingling, cold feeling and blanching of at least one finger tip, according to a temporal criteria of symptoms were present now or have been present on at least 4 days during the last 7 days, or symptoms have been present on at least 4 days during at least one week in the last 12 months. It was analyzed the severity of the complaints (interference with current activities) and the simultaneous occurrence of multiple symptoms. The causes of medical consultation in the last year were analyzed (osteo-articular pathology of the vertebral spine, of the upper and lower limbs, depressive syndromes and other complaints of the lower limbs among others). In the end, the relation between persistent complaints and musculo- skeletal pathology related to work activities was analyzed, considering particularly the age of the workers and the existence of osteo-articular pathology.

A tennis player with hand claudication.

The case of a professional tennis player presenting exercise-induced hand pain with late appearance of digital blanching is reported. A bilateral hypothenar hammer syndrome and stenosis of the common palmar digital arteries close to the head of the metacarpals where the racket handle exerts its maximal force was observed with arteriography. As the patient decided to stop tennis practice, the condition improved without any medication. Six months after stopping tennis he was symptom free. Three conclusions can be drawn from this case report: 1) arteries of both hands can be injured by intense tennis practice, 2) pain in the dominant hand during tennis practice can be due to arterial insufficiency even in the absence of digital blanching which is a sign of severity, 3) hypothenar hammer syndrome is the main cause but stenosis of the common palmar digital arteries can possibly contribute to the ischemic phenomenon. Early recognition is important to avoid ineffective treatment and permanent symptoms. Therefore, we recommend an arterial examination in tennis players suffering from exercise-induced hand pain even in the absence of digital blanching which can be only a late manifestation.

Assessing the impact of high-pressure processing on selected physical and biochemical attributes of white cabbage (Brassica oleracea L. var. capitata alba)

The aim of this study was to investigate the effect of combined pressure/temperature treatments (200, 400 and 600 MPa, at 20 and 40 °C) on key physical and chemical characteristics of white cabbage (Brassica oleracea L. var. capitata alba). Thermal treatment (blanching) was also investigated and compared with high-pressure processing (HPP). HPP at 400 MPa and 20–40 °C caused significantly larger colour changes compared to any other pressure or thermal treatment. All pressure treatments induced a softening effect, whereas blanching did not significantly alter texture. Both blanching and pressure treatments resulted in a reduction in the levels of ascorbic acid, effect that was less pronounced for blanching and HPP at 600 MPa and 20–40 °C. HPP at 600 MPa resulted in significantly higher total phenol content, total antioxidant capacity and total isothiocyanate content compared to blanching. In summary, the colour and texture of white cabbage were better preserved by blanching. However, HPP at 600 MPa resulted in significantly higher levels of phytochemical compounds. The results of this study suggest that HPP may represent an attractive technology to process vegetable-based food products that better maintains important aspects related to the content of health-promoting compounds. This may be of particular relevance to the food industry sector involved in the development of convenient novel food products with excellent functional properties

High pressure processing of swede (Brassica napus): Impact on quality properties

The effects of combined pressure/temperature treatments (200, 400 and 600 MPa, at 20 and 40 °C) on the physical and nutritional properties of swede roots (Brassica napus var. napobrassica) were assessed. Changes induced by high pressure processing (HPP) on the original properties of swede samples were compared with those produced by thermal treatment (blanching). All studied treatments altered the physical properties of swede, resulting in a loss of hardness and water binding capacity. The strongest alteration of texture was observed after HPP at 400 MPa, while 600 MPa was the treatment that better preserved the texture properties of swede. Blanching caused less total colour changes (ΔE) than HPP. Antioxidant properties of swede were measured as total antioxidant capacity, ascorbic acid and total phenol content. All treatments caused a loss of antioxidant capacity, which was less pronounced after HPP at 600 MPa and 20 °C and blanching. Four glucosinolates were detected in swede roots, glucoraphanin, progoitrin, glucobrassicanapin and glucobrassicin. Glucobrassicanapin and glucobrassicin contents were reduced with all studied treatments. Progoitrin content was not affected by blanching and HPP at 200 MPa. HPP at higher pressure levels (400 and 600 MPa), though, induced an increase of progoitrin levels. The results indicated that blanching and HPP at 600 MPa and 20 °C were the treatments that better preserved the original quality properties of swede.

Extracción y medida de peroxidasa en pulpa de arazá (Eugenia stipitata MC Vaugh)

A technique for both extraction and activity measurement of peroxidase extracted from arazá (Eugenia stipitata Mc Vaugh) is described. Peroxidase from arazá pulp fruit was extracted using a combination of protein precipitation with acetone and extraction with 50 mM sodium buffer phosphate (pH 6.0). Optimum activity using guaiacol as H-donor was obtained at pH from 5.0 to 6.5, temperature from 60 to 75 °C, H2O2 between 10 to 15 mM and guaiacol from 80 to 160 mM. Thermal inactivation showed a first-order inactivation kinetic. Reactivation was observed when extracts were heated at 80 °C and afterwards incubated at 25 °C.

Moisture sorption isotherms of fresh and blanched pumpkin (Cucurbita moschata)

Moisture desorption isotherms of fresh and heat blanched pumpkins (Cucurbita moschata) were determined at three temperatures (30, 50 and 70 °C), using the standard, static-gravimetric method. The GAB, Oswin, BET, Halsey, and Henderson models were tested and, with the exception of the Henderson model, showed satisfactory fits to the experimental data. The GAB model was used to analyze the fitting ability to describe the isotherm type. The shape of the desorption isotherms of fresh and blanched pumpkin at 30 and 50 °C was intermediate to types II and III, and at 70 °C it was of type II for the blanched pumpkin and close to type II for the fresh sample. The influence of blanching on the decrease in equilibrium moisture was very small compared to the fresh samples and it was related to the loss of soluble solids during the pre-treatment. The isosteric heat of sorption measures indicated that a larger amount of heat was required to remove the water from the fresh samples than from the blanched ones.

Effects of peeling methods on the quality of cubiu fruits

Cubiu (Solanum sessiliflorum Dunal) is an Amazonian Basin native fruit. Its importance comes from its high contents of pectin. Currently, processing technologies are necessary for the substitution of the traditional system (small crops and small-scale processing) for a larger scale system and thus increase the use of biodiversity and promote the implementation of Local Productive Arrangements of agribusiness in the Amazon. This research aims to evaluate the methods of peeling cubiu. Ripe fruits were divided into lots (150 each) and subjected to the following treatments: immersion in 2.5% NaOH boiling solution for 5 minutes, exposure to water vapor, and immersion in water at 96 ºC for 5, 10, 15 and 20 minutes. The peel released during heat treatment and immediately removed under running tap water. In the control treatment, the fruits were manually peeled (unheated) with a stainless steel knife. The treatments were evaluated for completeness and ease of peeling, tissue integrity, texture, and peroxidase activity. The immersion in 2.5% NaOH boiling solution (5 minutes) stood out as the best treatment since it inhibited the enzymatic browning and intensified the natural yellow color of the cubiu fruit and easily and fully peeled the whole fruit more rapidly without damaging its tissues. This treatment was chosen as the most advantageous because it can promote simultaneous peeling and bleaching. Therefore, it is recommended for cubiu industrial processing.

Effect of process variables on the osmotic dehydration of star-fruit slices

The objective of this work was to study the effect of blanching and the influence of temperature, solution concentration, and the initial fruit:solution ratio on the osmotic dehydration of star-fruit slices. For blanching, different concentrations of citric and ascorbic acids were studied. The samples immersed in 0.75% citric acid presented little variation in color in relation to the fresh star-fruit. Osmotic dehydration was carried out in an incubator with orbital shaking, controlled temperature, and constant shaking at 120 rpm. The influence of process variables was studied in trials defined by a complete 23 central composite design. In general, water loss and solids gain were positively influenced by temperature and by solution concentration. Nevertheless, lower temperatures reduced water loss throughout the osmotic dehydration process. An increase in the amount of dehydrating solution (initial fruit:solution ratio) slightly influenced the evaluated responses. The process carried out at 50 ºC with a solution concentration of 50% resulted in a product with lower solids gain and greater water loss. Under these conditions, blanching minimized the effect of the osmotic treatment on star-fruit browning, and therefore the blanched fruits showed little variation in color in relation to the fresh fruit.

Variation of glucoraphanin and glucobrassicin: anticancer components in Brassica during processing

Effects of cold storage and three common cooking practices, blanching, sauteing, and microwave cooking at different time intervals, on the content of glucosinolate (GSL) anticancer components in six Brassica vegetables were investigated. Eleven GSLs including progoitrin, glucoraphanin, sinigrin, glucoalyssin, gluconapin, glucobrassicanapin, glucoerucin, glucobrassicin, 4-methoxyglucobrassicin, gluconasturtiin, and neoglucobrassicin were quantified using LC-MS and HPLC. Storage at 4 ºC indicated no significant loss of GSLs in broccoli, kohlrabi, and cabbage, and approximately 90-100% of the total concentration of aliphatic and indolyl GSLs were detected. Interestingly, glucoraphanin and glucobrassicin, known as a cancer prevention agents, increased approximately above 50% in broccoli, kohlrabi, and cabbage, while the amount of glucobrassicin decreased by 5% in cauliflower for 5 days at 4 ºC. Blanching of broccoli at 120 sec significantly (36%) decreased total GSLs; however, sautéing and microwaving decreased by13-26%. Individual GSLs have different response at blanching. These findings suggest that different processing methods for each vegetable would be preferred to preserve the nutritional qualities.

Thermal inactivation of polyphenoloxidase and peroxidase in Jubileu clingstone peach and yeast isolated from its spoiled puree

The thermal inactivation of yeast isolated from spoiled Jubileu peach puree and that of polyphenoloxidase (PPO) and peroxidase (POD) in cv. Jubileu, which is widely cultivated in southern Rio Grande do Sul state, Brazil, were studied. PPO and POD were extracted using the protein powder method and submitted to partial purification by precipitation followed by dialysis. The enzymatic activity was determined measuring the increase in absorbance at 420 nm for PPO and 470 nm for POD. The yeast used in this investigation was isolated from spoiled Jubileu peach puree at 22 °Brix, with total initial microbial count of 22 × 10² UFCmL- 1. Stock cultures were maintained on potato dextrose agar (PDA) slants at 4 °C and pH 5 for later use for microbial growth. In all cases, kinetic analysis of the results suggests that the thermal inactivation was well described by a first-order kinetic model, and the temperature dependence was significantly represented by the Arrhenius law. Both enzymes were affected by heat denaturation, and PPO was more thermostable. PPO was also more thermosTable than the yeast isolated from peach puree. The D60-values were 1.53 and 1.87 min for PPO and yeast isolated from spoiled Jubileu peach puree, respectively.