Dependence of carotenoid content and temperature-time regimes during the traditional slow drying of red pepper for paprika production at La Vera county

Evolution of the carotenoid content has been studied during dehydration process of red pepper fruits (Capsicum annuum L.) for paprika production using a handcrafted technique, typical of La Vera County (Spain), which is based on slow drying at mild temperatures, conditions that were monitored during the complete process, to correlate the evolution of the pigment content with drying parameters. This tracking allowed to state that during drying of fruits, the carotenoid content goes through different stages either decreases or increases which are reflect of the processing conditions. In the present study, when imposed conditions were milder a more regular evolution was denoted, while more severe temperature-time regimes meant an irregular trend, although dry fruits contained similar carotenoid values with respect to the starting ones in all cases. Considering different isochromic carotenoid fractions and major individual pigments, the study revealed that any of them are preferentially either degraded or biosynthesised, what implies a certain balance between different groups of reactions that carried out during dehydration. In the sight of the positive retention of the carotenoid content and retinol equivalent values, conditions achieved in one dryer could be used by paprika producer for subsequent standardization of this traditional process by using the proper technical equipment.     

Changes of quality characteristics of pepino fruit (Solanum muricatum Ait) during convective drying

Quality assessment of pepino fruit preserved through convective dehydration was investigated in this work. The effect of process temperature (50, 60, 70, 80 and 90 °C) on physicochemical properties, colour, non‐enzymatic browning, vitamin C, total phenolic content, antioxidant activity and firmness of the fruit were considered. When comparing the fresh with the corresponding dehydrated pepino samples, it was shown that the drying conditions resulted in important reductions of proteins and crude fibres. Discoloration of fruit was noticeable for all treatments due to effects of non‐enzymatic browning and changes in chromatic coordinates leading to a modification of the original colour. Regarding vitamin C and total phenolic content, an increase of drying temperature resulted in a considerable reduction of both initial compounds contents. Antioxidant activity showed an important decrease especially at low temperatures (e.g. 50 °C). Softening of the dried product was observed for all the treatments indicating structural modifications of the fruit due to thermal process.     

Comparative study of the effect of the maturation process of the olive fruit on the chlorophyll and carotenoid fractions of drupes and virgin oils from Arbequina and Farga cultivars

Two varieties of olive fruit (Arbequina and Farga) have been characterized by their contents and types of chlorophyll and carotenoid pigments during the olive ripening. Independently of the initial content, the pigment concentrations decreased with fruit maturity. Chlorophyllides a and b, esterified xanthophylls and α-carotene were only detected in Arbequina fruits. Moreover, the synthesis of esterified xanthophylls, when the skin fruit colour changed from green to turning-colour only, was observed in this variety. The pigments transferred from fruit to the oil were also studied. All the pigments that were found in the fruit were transferred to the oils, in addition to derivative pigments associated with acidic medium in the oil extraction process. The destruction of the chlorophyll fraction was greater than of the yellow pigments during the olive oil extraction process.     

Developments and Trends in Fruit Bar Production and Characterization

Fruits serve as a source of energy, vitamins, minerals, and dietary fiber. One of the barriers in increasing fruit and vegetables consumption is time required to prepare them. Overall, fruit bars have a far greater nutritional value than the fresh fruits because all nutrients are concentrated and, therefore, would be a convenience food assortment to benefit from the health benefits of fruits. The consumers prefer fruit bars that are more tasted followed by proper textural features that could be obtained by establishing the equilibrium of ingredients, the proper choosing of manufacturing stages and the control of the product final moisture content. Fruit bar preparations may include a mixture of pulps, fresh or dried fruit, sugar, binders, and a variety of minor ingredients. Additionally to the conventional steps of manufacturing (pulping, homogenizing, heating, concentrating, and drying) there have been proposed the use of gelled fruit matrices, dried gels or sponges, and extruders as new trends for processing fruit bars. Different single-type dehydration or combined methods include, in order of increasing process time, air-infrared, vacuum and vacuum-microwave drying convective-solar drying, convective drying, and freeze drying are also suggested as alternative to solar traditional drying stage. The dehydration methods that use vacuum exhibited not only higher retention of antioxidants but also better color, texture, and rehydration capacity. Antioxidant activity resulting from the presence of phenolic compounds in the bars is well established. Besides this, fruit bars are also important sources of carbohydrates and minerals. Given the wide range of bioactive factors in fresh fruits that are preserved in fruit bars, it is plausible that their uptake consumption have a positive effect in reducing the risk of many diseases.     

Hot air dehydration of figs (Ficus carica L.): drying kinetics and quality loss

The dehydration of fruit from fig trees is normally achieved by sun drying. There is concern about the safety of the end product, mainly because there is a risk of the development of aflatoxins. These concerns can be overcome by artificial drying (oven dehydration). Fig fruits of a local cultivar, which were either pre‐treated by blanching or blanching plus sulphuring or not treated at all, underwent hot air dehydration under mild processing conditions in a pilot airflow cabinet dryer. Sampling was carried out at regular intervals to calculate the rate of dehydration and assess quality changes. Microbiological counts and nonenzymatic browning were also monitored. Pretreatments resulted in a shorter processing time, compared with control fruits. In general, a falling dehydration rate period was observed. A dramatic loss of ascorbic acid was recorded, while an informal sensorial assay of the dried fruits gave a positive assessment.     

Impact of limited drying on Momordica cochinchinensis Spreng. aril carotenoids content and antioxidant activity

Food product based on gac fruit (Momordica cochinchinensis Spreng.) arils have a high potential due to the high carotenoids content of this fruit. Drying is a key preparation step for carotenoids extraction from gac fruit in a economically viable process. The impact of different drying technics, temperature, final product moisture content on the carotenoid content, hydrophilic and lipophilic antioxidant activity (evaluated with three methods) and color of the gac arils is discussed based on laboratory scale experimental tests. The results highlight an optimal temperature between 50 °C and 60 °C to conserve the color, the carotenoid content and the antioxidant activity. Also, these properties are better preserved by limiting the drying to dry based moisture content between 15% and 18% while the advantages of drying for further processing and for refrigerated conservation for a few months are achieved.     

Use of Ultrasound for Dehydration of Papayas

This work evaluated the production of dehydrated papayas (Carica papaya L.) with low sugar content. The product was obtained applying ultrasonic waves to enhance the loss of sugar from the fruit. To achieve this goal, this paper examined the influence of the ultrasonic pre-treatment before air-drying on dehydration of papaya. Ultrasonic pre-treatment for air-drying of fruits was studied and compared with osmotic dehydration. This study allowed estimate of the effective diffusivity water in the air-drying process for papayas submitted to ultrasonic pretreatment. Results show that the water effective diffusivity increases after application of ultrasound causing a reduction of about 16% in the drying time. During ultrasonic treatment the papayas lost sugar (13.8% in 30 min), so such a pre-treatment stage can be a practical process to produce dried fruits with lower sugar content.     

Antioxidant and antimicrobial properties of organic fruits subjected to PEF-assisted osmotic dehydration

The effect of PEF pre-treatment prior to osmotic dehydration on mass transfer parameters, colour, antioxidant and antimicrobial properties in organic strawberries and kiwifruits was evaluated. An increase of water loss in both fruits upon the application of combined processes was noticed (up to 21.6%), while a decrease of solid gain was observed only in kiwifruit samples dehydrated in sucrose (about 45%). In general, the combined treatments were beneficial for colour maintenance in both fruit tissues. The antioxidant capacity (DPPH) and activity (ORAC) increased after PEF treatment, however, all the combined treatments reduced significantly these values (of about 20 and 28% for strawberry and of about 56 and 35% for kiwifruit, respectively for DPPH and ORAC methods). In general, PEF treatment alone was also effective with regard to an increase in the antimicrobial activity of the samples against the tested microorganisms (B. subtilis, E.coli, S. cerevisiae).Industrial relevancePEF pre-treatment coupled with osmotic dehydration could be applied at industrial level to obtain semi-dried fruit products. Moreover, both processes could be used as pre-treatments for drying process, in order to develop healthy and microbiologically stable fruit snacks. In fact, in the present work we observed that PEF pre-treatment alone promoted higher antioxidant and antimicrobial activity. The combined process decreased both parameters, suggesting that an accurate study is necessary to evaluate the benefits of these processes in terms of bioactive compounds retention and time and energy consumption in further drying process. The results of the present study could be used as a starting point for the industries to design novel products with intermediate moisture content intended for further processing.     

Optimization of osmotic dehydration of melons followed by air-drying

Osmotic dehydration represents a technological alternative to reduce post‐harvest losses of fruits. In this work, the influence of the osmotic solution concentration and osmotic solution to fruit weight ratio was examined on the osmotic dehydration of melons under vacuum. The process of osmotic dehydration followed by air‐drying was studied and modelled so that it could be optimised. The developed model has been validated with experimental data and simulations have shown that how the operating conditions affect the process. An optimisation was done using the model in order to search for the best operating condition that would reduce the total processing time.     

Phytochemical and antioxidant characterization of the fruit of black sapote (Diospyros digyna Jacq.)

Consumption of fruits and vegetables has been associated with a healthy state which has been attributed, in part, to their antioxidant capacity. Characterization of the bioactive compounds with antioxidant activity found in fruits cultivated in the tropic is limited. Thus, the objective of the present work was the characterization of phytochemicals and antioxidants of the fruit of black sapote (Diospyros digyna Jacq.). HPLC-DAD-Mass Spectrometry (HPLC-MS) analyses were used to identify and quantify phenolics, carotenoids and tocopherols. Total soluble phenolic content was 247.8 mg GAE/100 g fw (fresh weight). Important phenolics identified were sinapic acid, myricetin, ferulic acid, and catechin. Total carotenoid content was 399.4 ??g of ??-carotene/100 g fw, and ??-carotene and lutein were the main carotenoids identified. ??-Tocopherol concentration was 672.0 ??g/100 g dry weight. Antioxidant capacity as measured by the DPPH and FRAP assays was higher in the hydrophilic than in the lipophilic extract, and it is thought to be due mainly to the phenolic content of this fruit. Results suggest that the fruit of black sapote has an antioxidant capacity comparable to other important fruits, and its inclusion in the diet is therefore recommended.     

A Critical Review on the Spray Drying of Fruit Extract: Effect of Additives on Physicochemical Properties

Spray drying accomplishes drying while particles are suspended in the air and is one method in the family of suspended particle processing systems, along with fluid-bed drying, flash drying, spray granulation, spray agglomeration, spray reaction, spray cooling, and spray absorption. This drying process is unique because it involves both particle formation and drying. The present paper reviews spray drying of fruit extracts, such as acai, acerola pomace, gac, mango, orange, cactus pear, opuntia stricta fruit, watermelon, and durian, and the effects of additives on physicochemical properties such as antioxidant activity, total carotenoid content, lycopene and β-carotene content, hygroscopy, moisture content, volatile retention, stickiness, color, solubility, glass transition temperature, bulk density, rehydration, caking, appearance under electron microscopy, and X-ray powder diffraction. The literature clearly demonstrates that the effect of additives and encapsulation play a vital role in determining the physicochemical properties of fruit extract powder. The technical difficulties in spray drying of fruit extracts can be overcome by modifying the spray dryer design. It also reveals that spray drying is a novel technology for converting fruit extract into powder form.     

Effect of ultrasound‐assisted osmotic dehydration on cell structure of sapotas

BACKGROUND: Drying is a traditional way of fruit preservation. Because of the high energy costs associated with air‐drying, osmotic dehydration is often applied as a pretreatment to reduce air‐drying time. Ultrasound is an emerging technology with several applications in food processing. The effect of ultrasound on fruit tissue depends on the tissue structure and composition, and ultrasound might be beneficial to improve air‐drying efficiency, with consequent reduction in process costs. In this study the effect of ultrasound and ultrasound‐assisted osmotic dehydration on sapota tissue structure was evaluated. RESULTS: Ultrasound induced cell disruption and breakdown of cells with high phenolic content (dense cells) and also induced elongation of parenchyma cells. Ultrasound application combined with high osmotic gradient enhanced water loss and solid gain because of the formation of microscopic channels. Ultrasound‐assisted osmotic dehydration induced gradual distortion of the shape of cells, cell breakdown and formation of microscopic channels. Micrographs of the fruit tissue showed that ultrasound preferentially affected dense cells. CONCLUSION: Ultrasonic pretreatment was able to preserve the tissue structure of the fruit when distilled water was used as liquid medium. The application of ultrasound‐assisted osmotic dehydration resulted in severe changes in the tissue structure of the fruit, with consequent increase in the effective water diffusivity, because of the formation of microscopic channels and cell rupture. Copyright © 2009 Society of Chemical Industry     

Shrinkage of Mirabelle Plum during Hot Air Drying as Influenced by Ultrasound-Assisted Osmotic Dehydration

Convective drying in hot air is still the most popular method applied to reduce the moisture content of fruits and vegetables. Conventional hot-air drying of Mirabelle plum is considered to be a slow and energy intensive process. This is due to the fact that the waxy skin of Mirabelle plum has low permeability to moisture, a fact which results in high shrinkage. The aim of this study was to investigate the effect of ultrasound-assisted osmotic dehydration pretreatment on shrinkage of Mirabelle plum as a function of moisture content with the end goal of optimizing operating conditions that minimize shrinkage of the produce during drying. Results showed that application of ultrasound-assisted osmotic dehydration led to a significant (p < 0.05) decrease in shrinkage (from 76.41 to 64.05%). A linear relation between moisture loss and shrinkage was observed. Results indicated that shrinkage may be easily estimated from changes in moisture content, and independent of the drying rate. Inversely, determination of shrinkage would provide an indirect indication of moisture content.     

包装对半干型荔枝干贮藏品质的影响

为了抑制半干型荔枝干在贮藏过程中果肉褐变、微生物生长,本试验研究了半干型荔枝干水分含量分布及其水分活度情况,探讨了不同包装技术,不同包装材料对半干型荔枝干贮藏效果的影响。结果表明:试验用荔枝干果肉平均含水量为36.51%,平均Aw>0.73。脱氧包装技术对延缓半干型荔枝干果肉褐变效果显著,并表现出良好的抑菌效果,保鲜剂与脱氧剂对荔枝干褐变的抑制具有协同作用,包装材料的遮光性对果肉褐变的影响不明显;普通包装方式下,荔枝干果肉褐变快,不同包装材料间荔枝干的贮藏效果相差不大,因此采用普通包装时,包装材料的选择以经济、美观为标准即可。     

Polygalacturonase (PG) gene expression in <Emphasis Type="Italic">Musa acuminata</Emphasis> cultivars from Kerala

Banana cannot be preserved for a long time after harvesting due to a short shelf life. Fruit softening is associated with textural changes due to disassembly of the primary cell wall and modification of the structure and composition of various polysaccharides. Cell wall degradation is caused by the action of various cell wall hydrolase enzymes. Polygalacturonase (PG) is the key enzyme involved in this process. The ripening period is different in cultivars maintained under domesticated cultivation in Kerala. PG activity was profiled in eight Musa acuminata cultivars from Kerala and expression analysis of the PG gene was accomplished using semi-quantitative RT-PCR. Maximum PG activity was observed in Palayankodan and minimum activity was observed in Kadali. Gene expression analysis showed variation between ethylene treated fruits and controls in Palayankodan, whereas the expression patterns in Kadali were similar. The fruit softening process is cultivar specific.     

Partial characterization of bifidobacterium breve C50 cell-free whey compounds inducing modifications to the intestinal microflora

Cell-free whey obtained from milk fermented with Bifidobacterium breve C50 (Bb C50) has been shown to modify the intestinal flora in humans and mice. Previous work showed that no antibiotic-like or barrier effect due to overgrowing bifidobacteria was implied in the microbial modifications. The present study was focused on characterizing the compounds and mechanisms involved. Protein, sugar, and enzymatic profiles of Bb C50 whey were therefore determined and compared to those of a whey unable to modify the intestinal flora of humans and mice. No remarkable difference was noted except for a higher lactosidase activity in Bb C50 whey. Various physical treatments were then applied to fractions of Bb C50 whey. Activity was assessed in C3H mice by analyzing changes in the intestinal flora balance throughout a 15-d administration of each treated whey. Heating at 80 degrees C and aerobic storage for 2 wk completely abolished Bb C50 whey activities. In contrast, the addition of a reducing agent (cysteine hydrochloride), either at the beginning of a 15-d aerobic storage or prior to administration, as well as preserved these activities. Susceptibility to heating and oxidation suggested that an enzyme might play a role in the induced microbial changes. Since the Bb C50 lactosidase was partly inactivated by the oxidative treatment, it could support the in vivo activity. The enzyme might reach the intestinal lumen and partly degrade substrates, such as mucins, usually used by the intestinal flora. The released molecules might then favor the development of a new microbial balance.     

干燥方式对果蔬风味物质影响研究进展

近年来,我国果蔬加工业发展迅速,脱水果蔬加工已经成为增加农民收入提高农业效益、促进我国区域经济发展,在国内外市场占据较大优势的重要行业。然而,果蔬的风味物质是评价果蔬品质的重要指标,在干燥加工过程中其风味物质的种类及含量会发生较大的变化,本文重点概述了目前国内外关于热风干燥、真空冷冻干燥、微波干燥和联合干燥以及其它干燥技术对果蔬挥发性风味物质和非挥发性风味物质2个方面的影响以及不同干燥技术引起风味物质变化的原因方面的研究进展,在阐述当前国内外果蔬干燥技术在风味物质上的研究现状的基础上,分析了现状及存在的问题,提出了干燥技术在果蔬风味物质中的应用研究可能发展的方向,为干制果蔬风味品质的研究提供参考。     

SOFTENING AND BIOCHEMICAL CHANGES OF SAPOTE MAMEY FRUIT (POUTERIA SAPOTA) AT DIFFERENT DEVELOPMENT AND RIPENING STAGES

We investigated some of the physicochemical and biochemical factors associated with flesh softening of sapote mamey fruit during development and ripening. The activities of pectinmethylesterase (PME), polygalacturonase (PG) and β‐galactosidase (β‐GAL) enzymes were measured in fruits harvested at different development stages, and postharvest in two production seasons. The textural changes were most noticeable at the preclimacteric stage in ripening fruit. The water‐soluble pectin (WSP) increased at a different rate than firmness decreased. No correlation between PG or PME activity and changes in firmness was observed in ripening fruits, though a low correlation was seen between β‐GAL activity and softening in climacteric stage. Greatest loss of firmness occurred in climacteric stage. Fruit pulp softening was not dependent on a single enzyme activity.     

Effect of hot air,vacuum and infrared drying methods on quality of rose hip (Rosa rubiginosa) leathers

For the development of fruit leathers, a formulation containing rose hip pulp, sucrose and citric acid was used as initial material for the drying process. Three dehydration techniques were tested: forced hot air, infrared and vacuum, all carried out at 60 and 70 °C. All methods led to flexible, translucent fruit leathers at both temperatures. Colour and water activity were not affected by the dehydration method nor by the temperatures tested. Nutritional parameters such as antioxidant capacity (TEAC) and content of phenolic substances were measured. The best retention was achieved with vacuum drying at 60 °C being of 57.5% and 25.1%, respectively. ESEM observations were conducted to assess the effect of drying methods and conditions on microstructure of leathers. Various extents of sucrose crystallisation were inferred from surface images. Cross‐sectional micrographs showed that the size of pores was affected by the drying technique but not by temperature in the range studied.     

The characterisation and profile of the bioactive compounds in red guava (Psidium cattleyanum Sabine) and guabiju (Myrcianthes pungens (O. Berg) D. Legrand)

Red guava (Psidium cattleyanum Sabine) and guabiju (Myrcianthes pungens (O. Berg) D. Legrand) are small fruits that are native to southern Brazil. This study evaluated the physicochemical composition, antioxidant activity and functional compounds of both fruits. Red guava exhibited a large amount of dietary fibre. Guabiju showed more antioxidant activity, had a higher anthocyanin content and had a higher carotenoid content. In the guabiju fruit, β‐carotene represented 40.4% of the total carotenoids, and malvidin 3‐glycoside represented 60% of the total anthocyanin content. β‐Cryptoxanthin was the predominant carotenoid in red guava, representing 44.8% of the total carotenoids; cyanidin 3‐glycoside was the predominant anthocyanin, representing 51.7% of the total anthocyanins. These native fruits could represent an alternative to traditionally consumed fruits, and then, the characterisation of bioactive compounds of fruits such as red guava and guabiju represents important information to the consumers who looking for a healthy diet.