Optimisation of osmotic dehydration of 'Tommy Atkins' mango fruit

Osmotic dehydration of mango in sucrose solution as influenced by temperature (30–50 °C), immersion time (60–150 min) and solution concentration (40–60% w/w) was studied through response surface methodology. Responses of water loss and solid gain were fitted to polynomials, with multiple correlation coefficients ranging from 0.72 to 0.95, respectively. The fitted functions were optimised for maximum water loss and minimised incorporation of solids in order to obtain a product resembling non-processed fruit. Optimum conditions to obtain water removal >25% with solid uptake lower than 6% could be obtained using a 44% (w/w) sucrose solution concentration, temperatures up to 38 °C and immersion times up to 80 min.     

Effects of state/phase transitions on the quality attributes of mango (Mangifera indica L.) during frozen storage

Effects of different state/phase transitions (temperature fluctuations) on quality attributes of mango cubes during frozen storage were investigated. Temperature of frozen mango was modulated from ?65 °C to different states, namely, rubbery state , partially freeze‐concentrated state () and glassy states ( and ). Results revealed that frozen samples after 4 weeks of storage in a glassy state showed higher quality in hardness, drip loss, colour and ascorbic acid. Quality of mango still continued to change during frozen storage even in the glassy state without temperature fluctuations. Furthermore, there was a significant decrease in quality attributes of frozen mango subjected to temperature fluctuations above and . Current work indicates glassy state storage can improve retention of quality attributes in frozen mango and glassy state without temperature fluctuation was proposed as the most favourable frozen storage condition.     

Effects of different osmo‐dehydrofreezing treatments on the volatile compounds,phenolic compounds and physicochemical properties in mango (Mangifera indica L.)

The influences of different osmotic solution pretreatments (sucrose, glucose and maltose with concentration of 45%) on the volatile compounds, phenolic compounds and other physicochemical parameters in frozen mangoes were studied. Volatile and phenolic compounds were measured using SPME/GC‐MS and HPLC method, respectively. The results revealed that compared with untreated frozen mango, some volatile compounds (e.g. alcohols, aldehydes and some terpenes and esters) increased significantly and there were more compounds identified in osmo‐dehydrofrozen samples. These changes positively affected mango aroma and resulted in higher sensory scores for osmo‐dehydrofrozen samples. In addition, data on phenolic compounds showed that dehydrofrozen samples pretreated in glucose and sucrose had higher ρ‐hydroxybenzoic acid and quercetin contents, respectively, while samples pretreated in maltose showed higher ρ‐coumaric acid and sinapic acid contents compared with untreated frozen samples. The current work indicates that osmo‐dehydrofreezing can improve the retention of phenolic and aromatic compounds in frozen mango.     

Effect of osmotic dehydration on the drying kinetics and quality of cashew apple

The effect of different osmotic pretreatments on cashew apple drying kinetics and product quality were investigated. The osmotic pretreatment was carried out in an incubator at constant temperature and agitation. The drying process was conducted in a fixed bed dryer at different temperatures and constant air velocity. Experimental data were fitted successfully using the Page and the two‐term exponential models for dried fresh and pretreated fruit, respectively. It was found that drying rates of osmosed fruits decreased owing to the presence of infused solutes. Evaluation of the final product was performed by means of ascorbic acid content, water activity and sensorial test. The osmotic pretreated samples showed the highest vitamin C losses and the lowest water activity. The samples pretreated in sucrose solution had the highest acceptance.     

Effect of ripening stage and infusion with calcium lactate and sucrose on the quality and microstructure of frozen mango

The effect of the ripening stage and infusion with calcium lactate and sucrose on the quality and microstructure of frozen mango was investigated. Partially ripe and ripe mangoes cubes were infused in 1% calcium lactate solution or a combination of 1% calcium lactate and 50% sucrose solution for 1 h before freezing at ?20 °C and stored for 14 days. After thawing, both the partially ripe and ripe mangoes treated with the combination of calcium lactate and sucrose exhibited the highest firmness value, sensory firmness score and lowest drip loss. Light microscope images also illustrated less damage to the cell wall of mango pretreated with calcium and sucrose. The calcium‐reinforced structure of the fruit and osmotic dehydration with sucrose reduced the freezable water content and consequently limited ice crystal damage. Furthermore, partially ripe mango was more suitable for freezing than ripe mango due to its stronger cell wall structure.     

Degradation of quality attributes of sweetened Julie and Ogbomoso mango juices during storage

Changes in the quality attributes of sweetened Julie and Ogbomoso mango juices were investigated. Sweetened mango juices were processed, bottled and stored at 25 °C for 12 weeks. The titratable acidity, pH, total solids, ash, soluble solids and ascorbic acid contents were evaluated immediately after processing and subsequently at 2-week intervals. The L*, a* and b* (HunterLab) parameters were determined to evaluate colour changes due to non-enzymatic browning.Generally, the quality attributes of the sweetened mango juices decreased during storage. The titratable acidity, pH, total solids, ash, soluble solids and ascorbic acid contents decreased during storage. After 12 weeks of storage, the percentage ascorbic acid loss of sweetened Julie and Ogbomoso mango juices was 16.25 and 16.67%, respectively. Browning index, chroma and b* values increased during storage. Colour changes in sweetened mango juices were mainly due to b* value and chroma.     

不同渗透条件对琯溪蜜柚品质的影响

以琯溪蜜柚为原料,采用正交实验设计,研究不同渗透液含糖量(55%、60%、65%),不同渗透温度(50、55、60℃),不同料液比(1∶6、1∶8、1∶10)对蜜柚品质的影响。测定的指标包括失水率、抗坏血酸保存率、还原糖保存率、蔗糖增加率和总酸保存率。由多指标综合评分法得出的结果表明:渗透液含糖量65%,渗透温度60℃,料液比1∶10为最佳渗透脱水条件。不同渗透条件对蜜柚各营养指标均有影响,且呈现不同的影响效果。      

Evaluation of process conditions on osmotic dehydration and quality indexes of pumpkin (Cucurbita moschata) and further polymeric film selection for packaging and refrigerated storage

We studied the influence of composition and concentration of solutions and product size on mass transfer kinetics during Anco pumpkin osmotic dehydration (OD). Once optimal conditions were determined, samples packed in commercial polymeric films were microbiologically analysed during refrigerated storage. The optimal OD time was 3 h, when the efficiency index WL/SG (water loss/solid gain) was stabilised. At this time, 1.0 and 1.5 cm cubes presented the highest index value (about 11) in binary solution (sucrose 55°Bx). WL was higher in 1.0 cm cubes for each dehydrating ternary salt solution tested, and no significant differences in firmness were observed with Calcium Lactate addition. Thus, optimal condition for OD in ternary solutions was 180 min and 55°Bx – 2% NaCl. Microbiological determinations were done for dehydrated (55°Bx without/with 2% NaCl) and untreated samples, packaged in different polymeric films. The combination with lowest mesophilic and psychrophilic counts at day 10 was: samples dehydrated with ternary solution of sucrose-salt packed in Polypropylene film.     

Effect of osmotic dehydration on dielectric properties,microwave vacuum drying kinetics and quality of mangosteen

Mangosteen (Garcinia mangostana Linn.) with and without osmotic dehydration (OD) in sucrose solution was dried by microwave vacuum drying at 1200, 1440 and 1680 W. Because of water loss (49.12–49.98 g 100 g^?1) and solid gain (9.31–11.62 g 100 g^?1) during OD, dielectric constant, loss factor and loss tangent of mangosteen were significantly increased (P ≤ 0.05) to 24.82–25.12, 11.52–14.18 and 0.47–0.50, respectively. With the decreased initial moisture content and the modified dielectric properties, drying time of osmotically dehydrated mangosteen was shorter than that of mangosteen without OD. Moreover, an increase in microwave power enhanced drying kinetics. With OD, Tg of dried mangosteen was increased from ?7.01, ?3.00 to 11.11–25.96 °C. Hardness and lightness (seedless part) were significantly increased (P ≤ 0.05). Structure of dried seedless mangosteen was well protected, resulting in the improved rehydration ability (P ≤ 0.05). Nonetheless, rehydration ability of the mangosteen containing seed was not improved (P > 0.05).     

Osmotic dehydration of guava: influence of replacing sodium metabisulphite with honey on quality

Guava slices were subjected to pre-treatment by soaking in a solution containing 0.25% (w/v) sodium metabisulphite, 0.5% (w/v) ascorbic acid, 1% (w/v) citric acid, 1% (w/v) calcium chloride and either 0%, 1% or 3% (v/v) honey. A higher concentration of metabisulphite [0.5% (w/v)], but no honey, was also prepared as a reference. After osmotic dehydration, the guava slices were dried at 60 °C. During 24 weeks of storage, the measured texture values of products indicated that an addition of honey significantly delayed the increase in hardness and cutting work in guava slices compared to other treatments ( P  ≤   0.05). Pre-treatment with 0.5% (w/v) metabisulphite without honey or 0.25% (w/v) metabisulphite with 1% (v/v) honey maintained colour during storage better than with 0 or 3% (v/v) honey. The result showed good agreement with colour score evaluation. Overall results suggested that 1% (v/v) honey was the best pre-treatment condition.     

液氮冻结对冻藏雷竹笋品质的影响

目的 研究液氮的3种冻结温度和冻结至3种中心温度对冻藏雷竹笋品质的影响。方法 测定不同液氮冻结温度和中心温度的冻藏雷竹笋的汁液流失率、可溶性固形物和粗纤维含量、硬度、色差、挥发性风味物质和感官评分。结果 液氮冻结温度组中,-60℃组冻结雷竹笋的感官评分、硬度显著低于-90、-120℃组（p<0.05）,而汁液流失率、粗纤维含量、a*值显著高于-90、-120℃组（p<0.05）;雷竹笋原有挥发性风味物质的信号强度为：-120℃>-90℃>-60℃,冻藏过程中产生的挥发性风味物质的信号强度为：-120℃<-90℃<-60℃。中心温度组中,-6℃组冻结雷竹笋的感官评分、硬度显著低于-12、-18℃组（p<0.05）,而汁液流失率、粗纤维含量、a*值、b*值显著高于-12、-18℃组（p<0.05）;雷竹笋原有挥发性风味物质的信号强度为：-18℃>-12℃>-6℃,冻藏过程中产生的挥发性风味物质的信号强度为：-18℃<-12℃<-6℃。-12℃和-18℃组冻藏雷竹笋品质差异不显著。结论 降低液氮冻结温度加快了冻结速率,维持了冻藏雷竹笋较好的感官品质;冻结至中心温度-12℃时,雷竹笋内部大部分水分已完成冻结,此时转移至-18℃冰柜中对雷竹笋组织内部影响不显著（p>0.05）。     

辣椒果肉的渗透脱水效果研究

研究了不同渗透溶液对辣椒果肉的脱水效果,从失水率、固形物增加率、含盐量和色泽变化等方面综合分析了不同浓度的纯糖溶液(50%和65%)、纯盐溶液(10%和20%)和糖盐混合溶液(10%盐,50%糖)的作用效果。结果表明,蔗糖和盐混合溶液的脱水效果最好,8h的失水率可以达到54.20%,可溶性固形物增加率仅有7.53%,且含盐量更是低于纯盐溶液的含盐量变化,只增加了2.62g/100g干基。在渗透后的颜色方面,混合溶液渗透后的变化差异没有纯溶液渗透后的明显。     

Review: Effect of the combined application of edible coatings and osmotic dehydration on the performance of the process and the quality of pear cubes

The objective of the present work was to evaluate the combined effect of the application of edible coatings (sodium alginate and low methoxyl pectin) and different osmotic dehydration conditions (sucrose solution: 40 and 60 °Brix, temperatures: 20 and 40°C and times: 1, 2, 4, 8 and 16 h) on pear cubes (water loss, solid gain, performance ratio, the total colour differences, mechanical properties, phenolic content and sensory analysis). The results indicated that samples coated with low methoxyl pectin and treated under 60 °Brix for 16 h at both temperatures (20 and 40°C) presented the best process performance. Statistical analysis showed that the application of the coatings resulted in greater firmness and stiffness of the pear cubes at the end of osmotic dehydration. Besides, alginate coating best preserved the phenolic content (31.4%) than uncoated (26.04%) and pectin-coated (20.77%) ones. However, total colour differences were not improved with the use of edible coatings (alginate or pectin). In terms of quality, the samples coated with both hydrogels had good overall acceptability by the evaluators and good mechanical properties. However, further studies are required to decrease the difference in colour and leaching of bioactive compounds in pear cubes due to the osmotic dehydration treatment.     

Effects of osmotic pretreatment and frying conditions on quality and storage stability of vacuum-fried pumpkin chips

The effects of osmotic (OP), ultrasound-assisted osmotic pretreatment (UAOP) and frying conditions on quality and storage stability of vacuum fried pumpkin chips were investigated. The pumpkin samples were pretreated in maltodextrin solution and subsequently fried at different temperatures (90–110 °C) and time periods (10–30 min). The results demonstrated that the moisture content, water activity, lightness, yellowness and carotenoid content of the fried chips decreased, while oil content, hardness and a* (dark brown colour) value increased with increasing frying temperature and time. UAOP reduced about 16.0% of oil absorption and enhanced approximately 70% of carotenoid retention in the fried chips. UAOP samples were also more stable during storage than the untreated ones, indicated by lower degradation kinetics constants of key quality parameters. The proposed pretreatment could be an effective method for food industries to develop vacuum fried pumpkin chips with improved quality and stability.     

果蔬渗透脱水的研究进展及应用前景

主要论述了果蔬渗透脱水的研究进展 ,总结了影响渗透脱水效果的主要因素 ,概括了渗透脱水在果蔬的品质保持和节能方面的优势 ,它将作为果蔬加工的前处理方法而具有广阔的应用前景。     

不同浓度1-PentCP处理对芒果常温贮藏生理品质的影响

研究了不同浓度（1、5、50μL/L）的环丙烯类乙烯效应抑制剂1-PentCP（1-pentylcyclopropene,1-戊基环丙烯）常温（20±2）℃熏蒸处理20h对芒果果实（Mangifera indica L.）贮藏生理和品质的影响。结果表明,1-PentCP熏蒸处理能明显抑制果实的呼吸强度并延迟呼吸高峰的出现时间,延缓果实硬度、可滴定酸含量的下降和MDA（丙二醛）、SSC（可溶性固形物）含量的上升,并降低POD（过氧化物酶）、PPO（多酚氧化酶）酶的活性。说明1-PentCP处理能有效延缓芒果的后熟和衰老,抑制芒果贮藏期间品质的下降,其中以50μL/L1-PentCP的效果较佳。