Iron enrichment of whole potato tuber by vacuum impregnation

The effect of vacuum time, restoration time, steam-cooking and storage at 4 °C on the iron content of vacuum-impregnated (VI) whole potato was evaluated. Whole potato tubers were immersed in a 0.4 g/100 g iron (ferric pyrophosphate) solution. Vacuum pressure of 1000 Pa was applied for 0–120 min, and atmospheric pressure restoration for 0–4 h. The result indicated that the iron content of VI potatoes increased with vacuum and restoration time; 1 h vacuum-treatment potatoes provided 6.4 times higher iron content compared to raw potatoes, and 3 h restoration time supplied 6.4 times higher iron content (>4.1 mg/100 g fr.wt.) compared to raw potatoes. Moreover, VI-cooked unpeeled or peeled potatoes had 6 times higher iron content than un-VI-cooked unpeeled or peeled potatoes. European daily potato consumption (260 g) of the VI-cooked unpeeled and peeled potatoes provided adult men with 93–104% and 67–90% of the recommended daily allowance (RDA) of iron, respectively. Also, the daily potato consumption of the unpeeled and peeled potatoes could supply adult women with 43–48% and 31–41% of the RDA, respectively. This study indicated that VI treatment of whole potato was useful for enriching the iron content.     

Effectiveness of antibrowning agents applied by vacuum impregnation on minimally processed pear

Different isotonic solutions containing antibrowning compounds (EDTA, 4-hexylresorcinol, citrate and ascorbate), combined or not with calcium lactate, were applied to minimally processed (MP) pear samples (cv. Blanquilla) by using the vacuum impregnation (VI) technique in order to reduce enzymatic browning. Vacuum impregnated samples were packaged and colour, mechanical properties, development of respiration gases and volatiles in the package headspace and microbial counts were monitored throughout storage at 4 °C. VI treatments with ascorbate solutions and calcium lactate were the most effective to extending the shelf life of MP pear. These treatments caused fewer changes in colour, mechanical properties and volatile composition and slowed microbial growth. Calcium lactate led to a better preservation in terms of mechanical parameters but had minor effects on colour development during cold storage.     

Effect of osmotic dehydration and vacuum impregnation on respiration rate of cut strawberries

Respiration rate in terms of O₂ consumption and CO₂ production was determined in strawberry halves, both fresh-cut and vacuum impregnated with an isotonic solution. The experimental measurements were also carried out in osmodehydrated samples for different concentration levels (to 30 °Brix) at atmospheric pressure and by applying a vacuum pulse. Changes throughout time of O₂ and CO₂ concentration in the headspace of chambers containing the samples were analysed to determine respiration rates. The effect of temperature on respiration rate in fresh-cut and impregnated samples showed sigmoid behaviour where a sharp increase in respiration levels occurred between 5 and 10 °C. Osmodehydration treatments resulted in a great decrease in O₂ consumption but no notable changes in CO₂ generation, which suggests that anaerobic biochemical pathway became dominant respiration mode due to the treatments. Production of ethanol and acetaldehyde was detected in these cases in agreement with the anaerobic process.     

Comparison of diffusion of fructo-oligosaccharide components during vacuum impregnation and osmotic dehydration

The osmotic behaviour of fructo-oligosaccharides was investigated during osmotic dehydration of apple cubes. The effect of vacuum impregnation on discrete diffusion coefficient (D _eff) of oligomers was scrutinised. D _eff were determined using the solution of Fick’s unsteady-state diffusion equation developed by Rastogi and Raghavarao. The moisture content decreases logarithmically irrespective of the type of treatment. The applied vacuum does not influence the rate of decrease of moisture content, but it reduces the water content. There are not significant differences among the D _eff of oligomers. Vacuum impregnation has no effect on D _eff values, which are in narrow range of the order of 10⁻⁹ m² s⁻¹ in the observed set of unit operation parameters. The prediction by the used model is acceptable in all cases especially in traditional osmotic dehydration, where the relative standard deviation (RSD) is less than 10%, and it also demonstrates the altered mechanism of vacuum impregnation by the increased RSD values.     

The influence of vacuum impregnation on the fortification of apple parenchyma with quercetin derivatives in combination with pore structures X-ray analysis

The study aim was to investigate the vacuum impregnation (VI) technique for apple enrichment with quercetin glycosides from apple peel. Beside the determination of the quercetin content, structural effects on the apple parenchyma were analyzed by computerized microtomography (μCT). VI was an efficient method to enrich apples with quercetin derivatives which was affected by the apple cultivar, the vacuum pressure, the soluble solid concentration (SSC) and the viscosity of VI solution. After VI of 13 apple cultivars the quercetin content varied between 368 and 604 μg/g dry mass and correlated with the firmness of the native apple and the increased apple weight. The use of low SSC solution resulted in increased quercetin enrichment in contrast to apple pectin solutions with elevated viscosity. The μCT analyses demonstrate that VI was more effective in the inner apple sections than in the outer parts. The study indicates that differences of pore size and microstructure within the apple cortex substantially affected the enrichment process.     

腊肉真空腌制工艺条件的优化

以猪脊背肉为原料,研究了真空腌制工艺中真空压力、腌制液浓度、原料质量和真空腌制时间4个因素对其真空腌制速率的影响。单因素实验及正交实验结果表明,腊肉真空腌制的最佳条件为:真空压力86kPa、腌制液浓度25%、原料质量125g、真空腌制时间5h,方差分析结果显示该最佳工艺与其他各组工艺存在着极显著差异。     

Influence of ohmic heating and vacuum impregnation on the osmotic dehydration kinetics and microstructure of pears (cv. Packham’s Triumph)

The effect of ohmic heating (OH) and vacuum impregnation (VI) on the osmotic dehydration kinetics and microstructure of pears was studied. Three different dehydration levels (30, 40 and 50 °C) were used, by applying VI or not (OD) and OH (100 V). Dehydrated samples showed that the application of OH during the osmotic treatments had significant effects on the kinetics of water loss and sugar gain as well as on the microstructure of samples. The greatest water loss was observed with the OD-OH. The largest amount of solute gain and the smallest firmness loss were obtained in the VI-OH. In some treatments, the process time was reduced by as much as 40%. The SEM observations showed that cell deformation and cell rupture were significant in the OD-OH than on the VI-OH samples. The increases in the permeability of cell by OH explain the acceleration of mass transference and process time reduction.     

Effect of vacuum impregnation on the phenolic content of Granny Smith and Stark Delicious frozen apple <Emphasis Type="Italic">cvv</Emphasis>

ABTS•+ test, o-diphenols (spectrophotometric) and HPLC-DAD phenolic content in vacuum impregnated apple slices from Stark Delicious and Granny Smith cvv. were studied. Vacuum impregnation (VI) was carried out in a pilot plant using an aqueous solution containing 37.9% dextrose, 15.2% sucrose, 1.0% ascorbic acid, 0.25% calcium chloride and 0.25% sodium chloride. The impregnation time was 30 min and the vacuum pressure was 100 mbar; the temperature was 25 °C during all processing steps and the solution/fruit ratio was 11:1. At the end of VI, samples were left 5 min in syrup. They were then rinsed with water, drained in a vibrating screen and quickly frozen. A significant decrease (p < 0.05) of the o-diphenol content was seen (17.84 and 12.32% of the initial content in Stark and Granny varieties, respectively). The same trend was confirmed by HPLC-DAD where reductions in total phenols were 21.57 and 26.86% in Stark and Granny, respectively. Individual phenolic compounds showed different rates of depletion, although in some cases there was no reduction. The ABTS•+ test was strongly affected by the presence of ascorbic acid (AA), which was much higher in treated samples. Sensory evaluation showed higher values of hardness, crispness, juiciness and sourness in VI Granny Smith than VI Stark delicious, with a higher retention of texture parameters in the former. Finally, sweetness was slightly higher in VI Stark. An erratum to this article can be found at     

pH reduction and vegetable tissue structure changes of zucchini slices during pulsed vacuum acidification

A pulsed vacuum acidification treatment (PVA) applied to zucchini slices and the related response of vegetable tissues, were studied. Results showed that in comparison with a traditional acidifying-dipping at atmospheric pressure, PVA may improve the pH reduction as a consequence of the increase of acid solution-vegetable tissues contact area. Nevertheless, the low porosity fraction of fresh zucchini, the variability of the vegetable tissue structure and its mechanical properties did not allow to increase the acidification rate by increasing the vacuum level of 200 mbar. In particular, the study of structural changes showed that the liquid volume changes occurred without significant total volume variation due to the rigidity of vegetable tissues. Probably, this aspect reduced the deformation-relaxation phenomena which have great effect on liquid impregnation at both 200 mbar and 400 mbar. In addition, due to the low viscosity of acid solution it was hypothesize a great filling also at 400 mbar reducing the effect of the increase of vacuum pressure.     

Texture improvement of fermented minced pepper under vacuum impregnation with pectin methylesterase and CaCl2 during fermentation

Fermented minced pepper (FMP) usually suffers from the deterioration of texture quality during fermentation, which can affect sensory and consumer acceptance. In this study, vacuum impregnation (VI) with CaCl₂, pectin methylesterase (PME) and CaCl₂ and PME (PME + CaCl₂ + VI) were compared to improve the texture quality of FMP. FMP treated with PME + CaCl₂ + VI showed the relatively intact cells structure after fermentation. In that case, its firmness maintained high level, while water-soluble pectin (WSP) content was minimum after fermentation. Meanwhile, the molar ratio of most monosaccharides of WSP in PME + CaCl₂ + VI treated FMP decreased, while rhamnose (Rha) molar ratio significantly (p < 0.05) increased after fermentation. The high Rha content represents the stability of rhamnogalacturonan-I linear skeleton of WSP. The negative effect on molecular weight of WSP was delayed by PME + CaCl₂ + VI treatment, and its peak area and value increased after fermentation. Atomic force microscope images indicated that PME + CaCl₂ + VI treatment could retain the long chain and branch structures, and inhibit the degradation of WSP net-like structure at some extent. Hence, PME + CaCl₂ + VI treatment was effective to improve the texture of FMP and inhibit the solubilisation of WSP via the formation of cross-linked pectin chains between Ca²⁺ and demethylesterified pectin.     

Effect of ohmic heating and vacuum impregnation on the quality and microbial stability of osmotically dehydrated strawberries (cv. Camarosa)

The combined effect of osmotic dehydration/ohmic heating (OD–OH) and vacuum impregnation/ohmic heating (VI–OH) on physicochemical and quality parameters of strawberry (a_w, color, firmness and microstructure), as well as on microbial stability of storage samples at 5 and 10 °C, was analyzed. Treatments were carried out with a 65% (w/w) sucrose solution at 30 °C, and ohmic heating at 9.2, 13, and 17 V/cm electric field strengths, corresponding to applied voltages of 70, 100, and 130 V. Dehydrated samples showed that water loss was greater in OD–OH treatments at 17 V/cm. The greatest solute gain, least firmness loss and least color loss were obtained in the VI–OH treatment at 13 V/cm. The shelf-life of strawberries treated with VI–OH at 13 V/cm and stored at 5 °C was extended from 12 d (control samples) to 25 d. Furthermore, the VI–OH treatment at 13 V/cm was the best processing condition for dehydrating strawberries.     

Calcium fortification of vegetables by vacuum impregnation: Interactions with cellular matrix

Calcium fortification of vegetables by applying vacuum impregnation (VI) is an alternative in developing functional foods. Nevertheless, calcium ions can interact with the plant tissue, modifying its mechanical and vacuum impregnation responses. These effects were studied in eggplant, oyster mushroom and carrot samples. Sample VI was carried out with isotonic solutions containing (i) sucrose and calcium lactate and (ii) sucrose. From the analysis of sample impregnation and deformation levels, the slight influence of Ca presence on the impregnation behaviour of these products could be concluded. Nevertheless, mechanical behaviour of eggplant and carrot were notably affected by calcium, although no significant effects were observed in oyster mushroom (without pectin in their cell architecture). Energy dispersive X-ray microanalysis (EDXMA) in impregnated products showed that calcium impregnation occurs in the intercellular spaces of eggplant and oyster mushroom and in xylem of carrot.     

Control of Aeromonas on minimally processed vegetables by decontamination with lactic acid, chlorinated water, or thyme essential oil solution

Aeromonas is an opportunistic pathogen, which, although in low numbers, may be present on minimally processed vegetables. Although the intrinsic and extrinsic factors of minimally processed prepacked vegetable mixes are not inhibitory to the growth of Aeromonas species, multiplication to high numbers during processing and storage of naturally contaminated grated carrots, mixed lettuce, and chopped bell peppers was not observed. Aeromonas was shown to be resistant towards chlorination of water, but was susceptible to 1% and 2% lactic acid and 0.5% and 1.0% thyme essential oil treatment, although the latter provoked adverse sensory properties when applied for decontamination of chopped bell peppers. Integration of a decontamination step with 2% lactic acid in the processing line of grated carrots was shown to have the potential to control the overall microbial quality of the grated carrots and was particularly effective towards Aeromonas.     

Experimental determination of the dynamics of vacuum impregnation of apples

ABSTRACT:  Vacuum impregnation (VI) is a food processing method by which air and native solution are removed from porous spaces within a food and replaced by an external solution. In this study, an experimental device based on a previous design was built, including some modifications, in order to investigate the dynamics of the VI process. The device measured the net force exerted by a food sample submitted to the VI process using a load cell. The influence of the vacuum level and sample geometry was well quantified by the experimental procedure and the modified equipment using apple samples (Fuji var.) as a food model. The results indicated that the experimental device proposed in this study, together with the suggested procedure, is a useful tool to investigate the dynamics of VI processes. It is robust and versatile, and has the advantage of not requiring the determination of the water evaporated during the VI process in a separate experiment, which represents an increase in the accuracy of the results.     

蔬菜中草酸检测技术的研究进展

草酸是植物体内普遍存在的一种简单二元有机酸,大量存在于蔬菜中。草酸可以参与细胞体内pH和渗透压等的调节,以及植物病原菌防御反应与铝毒害解除,具有重要的生理功能。同时,过量的草酸对人体具有许多不利影响。作为一种抗营养物质,大量食用含草酸的蔬菜会显著影响人体矿物元素的吸收和增加患肾结石的风险,因此研究草酸的测定方法具有非常重要的现实意义。蔬菜中草酸含量的检测技术主要有滴定法、光谱法、色谱法以及电化学方法。每种检测技术各有优点,也都存在一定的局限性。本文主要对蔬菜中草酸的检测技术进展进行了概述,以期为蔬菜中草酸的检测及快速检测技术提供基础参考。     

胶乳浸渍改善涤纶纤维混抄纸强度的研究

主要探讨了七种胶乳浸渍对涤纶纤维与木浆纤维混抄纸页的增强作用。结果表明：通过胶乳浸渍可以明显改善纸页的抗水性能,在胶乳浸渍量为16％时,丁苯类、苯丙类、丙烯酸甲酯共聚物类和羧基丁苯类胶乳的抗水效果最好,胶乳浸渍后纸页的Cobb值由原纸的210g／m^2降低到20g／m^2左右;浸渍后纸页干湿强度性能大幅度提高,不同胶乳对纸页性能影响不同：在浸渍增加量为16％时,经聚氨酯胶乳浸渍后纸页的干裂断长最大,达到了4．79km,耐破指数达到了5．86kPa·m^2／g;经苯丙类胶乳浸渍后纸页的撕裂指数最大,达到了39.18mN·m^2／g。     

真空浸渍处理对调理草鱼片品质的影响

目的探究真空浸渍处理时,浸渍真空度和处理时间对草鱼片品质的影响,优化草鱼片调理工艺参数。方法采用真空浸渍法加工调理草鱼片,设计了响应面试验,研究浸渍真空度、处理时间和食盐添加量对草鱼片感官评分、NaCl含量和磷含量的影响,并以感官评分为指标优化了草鱼片调理工艺参数。结果浸渍真空度和处理时间对草鱼片色度、增重率、NaCl含量、感官评分均有显著影响,而浸渍真空度还对鱼片持水性有显著影响(P0.05)。随着浸渍真空度升高、处理时间延长,调理草鱼片的增重率、持水性和NaCl含量逐渐增加,而调理草鱼片白度下降。浸渍加工草鱼片的适宜调理工艺参数为浸渍真空度80 kPa、食盐添加量1%、处理时间6 h。在该条件下,调理草鱼片的感官评分最高。结论使用真空浸渍处理可获得品质优良的调理草鱼片,且所得调理草鱼片的NaCl、磷含量符合GB2760-2014《食品安全国家标准食品添加剂使用标准》的相关要求,可应用于实际生产。     

发酵蔬菜中乳酸菌抑菌性的研究

乳酸菌(Lactic Acid Bacteria)是一类能发酵碳水化合物产生乳酸的细菌,他广泛应用于发酵食品中,是发酵蔬菜中的有益菌群。乳酸菌的抑菌功能是通过产生各种代谢产物包括酸性物质、二氧化碳、过氧化氢和细菌素等来实现的。通过分析发酵蔬菜中微生物菌群结构的组成,介绍了乳酸菌对病原菌和腐败菌的抑制作用特点及作用机理,旨在为乳酸菌制品的加工、储藏提供理论依据,更好地将乳酸菌这一益生菌应用于各类食品加工的实践操作中。     

发酵蔬菜中乳酸菌抑菌性的研究

乳酸菌（Lactic Acid Bacteria）是一类能发酵碳水化合物产生乳酸的细菌，他广泛应用于发酵食品中，是发酵蔬菜中的有益菌群。乳酸菌的抑菌功能是通过产生各种代谢产物包括酸性物质、二氧化碳、过氧化氢和细菌素等来实现的。通过分析发酵蔬菜中微生物菌群结构的组成，介绍了乳酸菌对病原菌和腐败菌的抑制作用特点及作用机理，旨在为乳酸菌制品的加工、储藏提供理论依据，更好地将乳酸菌这一益生菌应用于各类食品加工的实践操作中。     

真空浸渍技术在改善果蔬采摘后的品质特性中的应用进展

针对真空浸渍技术在改善果蔬采摘后的品质特性中的应用及作用原理,以及该技术近些年的研究现状和进展进行了详细综述,为该技术在果蔬采摘后的进一步应用研究提供了参考。