Ascorbic acid content in exotic fruits: A contribution to produce quality data for food composition databases

Ascorbic acid (AA) is a water-soluble vitamin mainly present in fruits and vegetables. Food Composition Databases (FCDB) provide detailed information on nutritionally important components in foods. However, in some FCDB there is a significant lack of information on vitamin C content. The aim of this study is to produce new data for FCDB by measuring the AA content in 26 types of exotic fruits and to evaluate the nutritional value of these fruits as a source of vitamin C. In this study, the analytical method used to measure ascorbic acid content is an economic, rapid and previously validated High Performance Liquid Chromatography (HPLC) method. Ascorbic acid content per 100 g of edible portion ranged between 0.925 ± 0.018 mg for kiwano and 117 ± 1.64 mg for arbutus. For all the analyzed exotic fruits and considering a mean daily consumption of 100 g/day, twelve of them provide more than 30% of the Dietary Reference Intake. About a quarter of the analyzed exotic fruits are not found in any of the five FCDB considered in this study. The worldwide global market is expanding the production and consumption of fresh fruits and vegetables, mostly exotic, increasing the need of updating the food composition databases with high quality data. The analytical results obtained in this study are an important source of reliable data to be included in the Portuguese food composition database.     

Postharvest Gibberellin and Heat Treatment Effects on Polyamines, Abscisic Acid and Firmness in Lemons

Lemons at two ripening stages were vacuum-infiltrated with 100 ppm of gibberellin A₃ (GA₃) or heat-treated at 45°C, and then stored at 15°C for 3 wk. Both treatments increased fruit firmness either in stage 1 or in stage 2. Also, the levels of free putrescine and spermidine in the skin were higher in treated lemons than in controls but spermine concentration did not show significant differences, in fruits of either stage. GA₃ treatment was the most effective in retarding the color change during storage, especially in stage 1 fruits, which was related to the lowest levels of abscisic acid found.     

Limonoids in Pummelos [Citrus grandis (L.) Osbeck]

Juice and seeds from 16 cultivars of mature pummelo fruits were analyzed for limonoid content. Pummelo juice contained an average of 18 ppm limonin and 29 ppm total limonoid glucosides. Compared to other juices, ptmnnelo contained very high concentrations of limonin and very low concentrations of limonoid glucosides. Limonin, nomilin, obacunone and trace amounts of deacetyhromilin were found in pummelo seeds. The 17–β-D-glucopyranoside derivatives (glucosides) of nomilin, nomilinic acid and obacunone were also present. Total limonoid aglycone concentration in the seeds ranged from 773 ppm to 9,900 ppm and total limonoid glucosides ranged from 130 ppm to 1,912 ppm.     

Microscopic investigations and pharmacognostic techniques for the standardization of the fruits of Rosa laxa Retz

Rosa laxa Retz., a shrub belonging to the family Rosaceae, is widely distributed in the northern foothills of the Tianshan Mountains in Xinjiang, China. The fruits of R. laxa (FRL) has antibacterial, hypolipidemic, and antioxidant effects. In this study, FRL was subjected to pharmacognostic identification of its source, morphology, microscopic characteristics, and physicochemical properties. The microscope showed that the cross-sectional features of FRL were obvious, and the FRL powder contained vessel, parenchyma cells, exocarp cells, pollen grains, and cluster crystals. Scanning electron microscopy (SEM) analysis results show that numerous villi and many small particles (particle size of 5–50 μm) were observed in the FRL powder, and there are many gullies on the surface of the particles. In addition, the secondary metabolites of FRL were characterized via ultraviolet–visible (UV–Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and thin-layer chromatography (TLC). Results showed that FRL contains various secondary metabolites, including flavonoids, phenolic acids, glycosides, and tannins. Water as the extraction solvent had the highest extraction rate and the contented of total flavonoids was 2.88 mg/g, and the contented of total polyphenols was 54.89 mg/g. Moreover, TLC identification revealed that it contains catechin and tiliroside. These parameters of FRL, which are reported herein, are important to the development of the pharmacognostic standards, as well as in the identification and quality control of FRL.     

Factors affecting sample extraction in the liquid chromatographic determination of organic acids in papaya and pineapple

A solvent extraction method was developed for the extraction of organic acids (oxalic, citric, tartaric, L-malic, quinic, succinic and fumaric acids) in papaya and pineapple. Central composite design “2ⁿ + star” was used in order to optimise the following extraction parameters: number of extractions, composition of the extractant mixture, extraction time and extraction temperature. Optimal conditions for extraction were determined by experimental design using response surface methodology. The results suggest that the extractant composition is statistically the most significant factor and that the optimum values for the variables are: three (number de extractions), water as extractant, 60 min (extraction time) and 65 °C (extraction temperature). The separation and determination of the organic acids was carried out by liquid chromatography with UV–Vis detection.     

The use of packaging techniques to maintain freshness in fresh-cut fruits and vegetables: a review

Browning and other discolourations, softening, surface dehydration, water loss, translucency, off-flavour and off-odour development, as well as microbial spoilage are some of the most frequent causes of quality loss in fresh-cut products. Nowadays, the use of innovative modified atmospheres and edible coatings stands out among other techniques in the struggle for maintaining freshness and safety of fresh-cut fruits and vegetables. A few studies have demonstrated the effectiveness of these techniques when applied to different fresh-cut commodities. However, treatment and storage conditions for fresh-cut fruits are still being largely explored to better keep their fresh-like quality attributes. This review discusses the recent advances in the use of innovative modified atmosphere packaging (MAP) systems to maintain freshness of fresh-cut fruits and vegetables. Furthermore, special attention is devoted to the development of coatings that can be used as a complement or alternative to MAP.     

Addition of cashew tree gum to maltodextrin-based carriers for spray drying of cashew apple juice

This study involved an attempt to totally or partially replace maltodextrin DE10 (MD10) by cashew tree gum (CTG) as a drying aid agent in spray drying of cashew apple juice. The objective was to evaluate the impact of drying aid/cashew apple juice dry weight ratio (D/C, ranging from 3 to 5) and degree of replacement of MD10 with CTG (CTG_R, ranging from 0% to 100%) on ascorbic acid retention (AAR), hygroscopicity, flowability and water solubility of spray dried cashew apple juice powder. AAR was increased from 72.90% to 95.46% by increasing D/C from 3 to 5. CTG was shown as a promising maltodextrin replacer, being more effective than the latter to decrease powder hygroscopicity. The most adequate drying conditions (D/C = 5, CTG_R≥50%) resulted in more than 90% of AAR, and produced a powder with good flowing properties and water solubility.     

The Application of Heat Pump in Drying of Biomaterials

The UN estimates that 6.4 billion people will be living on Earth by the year 2000. As a consequence, dried biomaterials demand will rise and equipments will have to be built or redesigned to accomadate changes. The design and innovations on industrial dryers require fundamental knowledge conceived in laboratory units. The new heat pump dryer operates at a wide relative humidity and the air temperature is adjustable from -20 to 100'C. Above and belw freezing point drying modes are done in the same plant which allows the control of biomaterial properties. The technique consists of two stages, unbound weakly held water removal by freeze drying. and tightly bound moisture desorption by medium temperature drying. The fluidized and shelf heat pump dryers have the required features to dry heat sensitive biomaterials. The dryers were built and extensive research on biomaterials has been conducted at The Norwegian Institute of Technology. Many emeriments were done on effect of heat pump drying conditions on-enrime and biological active bacteria solutions, fruits, cod fish, fish feed and shrimps. At optimum heat drying conditions, the bacteria Rhodococcus reached 100% viability and dried biomolecules attained full biolosical activity. The heat pump dryer allowed adjustment of the bio-mterial properties and quality according to its phase, shape and size. Dried samples showed improvements on survival rate. rehydration, colour, hardness and mono-multimolecular sorption isotherms over poorly dried products. Beneficial results were achieved for nearly all tests. This indicates that the heat pump dryer application has high potential in processing heat sensitive biomaterials.     

Studies on Dehydration of Sapota (Achras zapota)

Sapota (Achras zapota) is a tropical fruit found in several parts of India. It is one of the most popular fruits besides mango, custard apple, and several others. Once ripe, it needs to be consumed within a couple of days due to the highly perishable nature of this exquisite fruit variety. The best way to increase the shelf-life is through the process of dehydration of peeled sapota. In the present study, the convective air drying of sapota pulp was carried out and compared with low-temperature drying techniques such as heat pump-assisted drying and freeze drying. The sapota paste was dried in a convective dryer to study the effect of operating parameters such as air temperature and air velocity. In addition, the effect of additives such as oat and wheat fibers and the paste thickness on drying was also studied. The critical analysis of dehydrated sapota was carried out in terms of water activity, sugar content, color, and rehydration ratio. The drying data were analyzed using Page's model and Newton's model on the basis of root mean square error (RMSE), reduced χ square (χ²) and correlation coefficient (R²).     

水土流失区低产柑桔园改造若干技术问题

通过病虫害防治、施肥方法的改进、保花保果合理修剪、科学灌水措施的实施，使水土流失区的低产柑桔园连续９年增产、稳产、平均年产量达１１．４ｔ，平均株产量为２８ｋｇ．