The effect of freezing on the hot air and microwave vacuum drying kinetics and texture of whole cranberries

Abstract

The aim of this study was to evaluate the effect of convective and cryogenic freezing, hot air convective drying (HACD) at 60, 70, 80, and 90?°C and microwave vacuum drying (MWVD) at 100, 150, 200, 300, 450, and 500?W on the drying kinetics and texture of whole cranberries. Effective moisture diffusivities and drying rates were higher, whereas drying times were shorter for the samples dried by MWVD compared with the samples processed by HACD. The drying kinetics of cranberries during MWVD was discussed based on the hypothesis postulating that changes in the drying rate of cranberries during MWVD can be explained by and correlated with changes in the pressure gradient on material surface. Cranberries processed by MWVD were characterized by significantly greater hardness, gumminess, and chewiness in comparison with HACD samples. MWVD was found to be an effective method for producing dried snacks characterized by hard and crispy texture and considerable resistance to stress associated with manufacturing, packaging, storage, and delivery. HACD produced brittle fruit that were difficult to store and transport and were not fully suitable for direct consumption. Convective freezing before MWVD improved the overall appearance of cranberries, whereas cryogenic freezing combined with high temperature HACD adversely influenced the drying rate and produced dried cranberries with suboptimal overall appearance.     

Studies on the response of ‘Tifblue’ and ‘Woodard’ rabbiteye blueberries to fertilizers

A field study was conducted to investigate the effects of three fertilizer placement methods and 11 fertilizer formulations on plant survival, economics of replanting, yield, and fruit size of two rabbiteye blueberry (Vaccinium ashei Reade) cultivars Tifblue and Woodard. Fertilizer rates were either mixed with the soil under plants (before planting), sidedressed, or half-rate was placed under plants with the other half sidedressed. Fertilizers at planting caused a total of 34% Woodard and 12% Tifblue plants to die as compared to 6% for Woodard and none for Tifblue when no fertilizer was applied. Fertilizer formulas 2-1-1 and 5-10-10 oxide ratios placed under Woodard plants caused 100% mortality whereas Tifblue fertilized with oxide ratios 2-2-2 and 5-10-10 under plants reached the maximum 50% mortality. Splitting fertilizer placement under the side of the plants resulted in less Woodard plant mortality (30%) than placing all the fertilizer under plants (54%). However, plant mortality for the side/under group was not different than sidedressing all fertilizer (23%). A planted hectare in this experiment consisted of 1852 Tifblue and 926 Woodard plants, providing one Woodard plant to pollinate two Tifblue plants. Based on the results obtained, the 5-10-10 fertilizer placed under plants would be expected to cause half the Tifblue (926 plants) and all the Woodard (926 plants) to be replanted. Plant costs alone was estimated to be $2315 with additional replanting costs of $93 for Tifblue and much higher for Woodard. Sidedressing 5-10-10 fertilizer eight weeks after planting would have prevented plant mortality. Placement of various fertilizers under Woodard or Tifblue plants resulted in a significant increase in plant mortality as compared to side placement of fertilizers. Yield loss due to plant mortality increased linearly with the N level of the fertilizers (ranging from 0 to 2) for both cultivars. Woodard fruit size was not affected by fertilizer placement but placing fertilizers under Tifblue plants produced smaller yields with larger fruit than sidedressed plants. Blueberry plants in a virgin acidic soil may experience no reduction in yield if fertilization is completely eliminated.     

Phenolics of Vaccinium berries and other fruit crops

The concentrations and profiles of phenolics of selected fruit crops common in the Western diet, including several Vaccinium species, were examined to better understand how these crops may be useful sources of phenolic phytochemicals. Vaccinium fruit had a high phenolic concentration compared to non‐Vaccinium fruit. Some Vaccinium fruit were particularly rich in certain phenolic subgroups, especially anthocyanins and pro‐anthocyanidins. Among the pro‐anthocyanidin oligomers measured using fluorometric and mass spectroscopic detection, the trimers and tetramers were most abundant, while pro‐anthocyanidins with a degree of polymerization greater than 8 were least abundant. As biomedical studies determine which phenolic structures are associated with particular bioactivities, information on the phenolic concentration and profile of selected species will be useful in developing specific uses for fruit crops in human health. Methods were compared to assess the usefulness of simpler versus more sophisticated means of phenolic analysis. The phenolic components of fruit extracts were purified approximately 20‐fold, and not qualitatively altered, by C18 solid‐phase extraction. However, fruit extracts obtained from C18 solid‐phase extraction differed in their relative abundance of phenolic components. Colorimetric and HPLC‐DAD measures of phenolic concentration were correlated (R² = 0.79), as was pro‐anthocyanidin concentration detected fluorometrically and by mass spectrometry (R² = 0.44). Copyright © 2007 Crown in the right of Canada and Society of Chemical Industry     

大兴安岭红豆果汁及果汁饮料的研制与加工

详细阐述了野生红豆浆果的加工工艺、果汁的无菌处理、冷藏方法及果汁饮料的研发。由于红豆浆果的果胶含量较高（达0.3%以上），在果汁加工中采用添加果胶酶的方法，以提高果汁的出汁率，同时对果汁进行澄清处理，使最终果汁产品澄清透明，长期贮存无沉淀。     

Allelopathic effect of phenolic acids from humic solutions on two spruce mycorrhizal fungi:Cenococcum graniforme andLaccaria laccata

The aim of this investigation was to determine the impact ofp-hydroxyacetophenone,p-hydroxybenzoic acid, catechol, and protocatechuic acid on respiration of two spruce mycorrhizal fungi:Laccaria laccata andCenococcum graniforme. These phenols are produced byVaccinium myrtillus,Athyrium filixfemina, andPicea abies, predominant species of spruce forests in the Alps, and they are also present in humic solutions at 10^–10 M or 10^–5 M. Respiration of the two fungi was inhibited by the four phenolic acids, even at concentrations ranging from 10^–5 M to 10^–7 M. These data show phenolic acids from humic solutions have biological activity at extremely low concentrations, suggesting a contribution ofV. myrtillus, A. filixfemina, andP. abies to allelopathic inhibition of mycorrhizal fungi.     

笃斯越桔叶片黄酮类化合物分离组分I结构鉴定

本实验重点研究了笃斯越桔叶片黄酮类化合物分离组分I与特殊试剂颜色反应,紫外光谱特征判断其基本结构为黄酮醇黄酮,为进一步拓宽笃斯越桔在食品领域和药品领域奠定研究基础。     

乌饭果酒发酵工艺的研究

以乌饭树的果实为原料,分析了发酵条件对发酵过程的影响,通过单因素试验和正交试验,得出乌饭果酒的发酵优化条件为乌饭果实预处理打浆后,经100mg/kg的SO2处理,用120mg/kg果胶酶进行酶解,接种0.20%酵母,于25℃发酵8d,14~18℃后发酵20d,可得到口感纯正、营养丰富的乌饭果酒,为乌饭果酒新产品的开发提供参考。     

长白山笃斯越桔果实原花青素浸提工艺的研究

本实验以吉林省长白山野生笃斯越桔为研究对象,对比分析了料液比、浸提温度、浸提时间、浸提次数等工艺参数对原花青素浸提率影响情况,并利用L9(34)正交试验设计优化出最佳浸提工艺参数为:浸提溶剂60%乙醇,浸提温度60℃,料液比1:50,浸提时间80min,浸提两次,原花青素得率9.40%,为深入研究笃斯越桔中原花青素分离纯化工艺奠定工作基础。