超声波辅助提取苹果皮中果胶的研究

[目的]探讨采用超声波辅助提取苹果皮中果胶的工艺条件。[方法]采用超声波辐射萃取法从苹果皮中提取了果胶,并采用单因素试验研究了不同萃取剂、溶剂、超声时间、超声波辐射功率、料液比、乙醇浓度及提取液pH值对果胶提取率的影响。[结果]确立了超声波条件下提取果胶的最佳工艺条件为：用盐酸调pH值为1.8,用水作为溶剂,料液比为1∶20,超声波功率为600W,超声波辐射时间为40 min,乙醇浓度为60%。该工艺条件下,果胶提取率可达12.9%。[结论]为综合利用资源及利用超声波提取苹果皮中果胶提供了一条可行性途径。     

微波辅助提取橘子皮中果胶的工艺研究

[目的]确定微波辅助提取橘子皮中果胶的最佳工艺条件。[方法]采用微波辐射萃取法提取橘皮中的果胶,通过单因素试验研究萃取剂类型、溶剂类型、料液比、微波辐射功率、微波辐射时间、乙醇浓度及pH值对果胶提取率的影响。[结果]以盐酸作为萃取剂,以水作为溶剂,料液比为1∶20,微波辐射功率为600W,微波辐射时间为4min,乙醇浓度为60%,pH值为1.8时,果胶提取率较高,达20.7%。[结论]微波辅助提取橘子皮中果胶的最佳工艺条件为：用盐酸调节提取液pH值为1.8,用水作为溶剂,料液比为1∶20,微波辐射功率600W,辐射时间4min,乙醇浓度60%。     

Utilization of fluted pumpkin fruit ( Telfairia occidentalis) in marmalade manufacturing

Marmalade was produced from fluted pumpkin ( Telfairia occidentalis) fruit. The fruit was pulped, boiled and filtered to obtain pectin extract. The extract was boiled at 102 °C for 30 min with the pH and sugar levels adjusted to 3.2 and 68.5 °Brix, respectively. Fruit shreds were added towards the end of boiling. Results of analyses showed that the pulp is rich in Na, K, Fe, P, Mn and pectin (1.01%), but low in protein (0.86%). The marmalade had a firm gel and was acidic (pH 3.15). Mold was absent and syneresis did not occur. The marmalade contained 68.5% total soluble solids and set at 52–56 °C. Sensory evaluation showed no significant difference (p = 0.05) in taste, consistency, spreadability and overall acceptability between fluted pumpkin marmalade and commercial orange marmalade. Both chemical and sensory results denote that the marmalade was highly desirable and compared favourably with similar preserves produced in Nigeria.     

加工番茄果实成熟过程中果胶积累特性

为探讨加工番茄果实成熟过程中果胶物质的积累特性，对3个加工番茄品种及不同果实生育期和不同坐果节位的果实果胶组成和含量进行测定分析。结果表明，3个品种果实的果胶物质均是由水溶性果胶(WSP)、草酸溶性果胶(OSP)和碱溶性果胶（ASP）构成。在绿熟期果实内以OSP和ASP为主，红熟期果实内以WSP和OSP为主；随着果实的成熟，果实内的WSP含量均呈上升趋势，ASP含量均呈下降趋势，OSP含量表现上升至粉红期后又逐渐降低的趋势；3个不同品种中，Q020 品种的总果胶（TP）含量最高，里格尔87 5品种的TP含量最少，Q020果实内的WSP、OSP和ASP在成熟过程中总体均高于里格尔87 5和屯河8号。     

Biochemical and physiological study of the firmness of table grape berries

Firmness is an essential quality parameter of table grapes (Vitis vinifera) for consumers, with grape bunches that contains soft berries less preferred, resulting in a reduction in the market price. The softening of grape berries has been commonly associated with cell walls, especially the disassembly of pectic polysaccharides. However, the process of berry softening is not completely understood. To investigate the softening process of grape berries, we compared the Thompson Seedless variety, which suffers significant economic losses due to fruit softening, and NN107, a new variety with a significantly higher level of berry firmness. The composition of the cell wall during the berry development of these two grape varieties was compared. NN107 berries had a greater amount of calcium and uronic acids in the cell wall material than Thompson Seedless grapes, suggesting a special role for calcium bridge formation in NN107. Additionally, polyacrylamide carbohydrate electrophoresis (PACE) analysis suggested differences between these varieties in pectin structure. Thompson Seedless grapes showed increased pectolyase hydrolysable site dynamics in the cell wall material and higher polygalacturonase activity than NN107. Immunohistochemistry focusing on the pectin structure confirmed the roles of both calcium bridge formation and cell wall integrity as they relate to a firmer grape berry phenotype.     

Benzyl-aminopurine (BAP) treatments delay cell wall degradation and softening,improving quality maintenance of refrigerated summer squash

Round summer squash are harvested before reaching full maturity and even though they are highly perishable, fruit postharvest handling is mostly based on storage at non-chilling temperatures. Finding complementary treatments minimizing deterioration and reducing postharvest losses would be extremely useful. In this work we evaluated the effect of postharvest cytokinin (CK) treatments on refrigerated round soft rind squash. Fruit were harvested at commercial maturity and sprayed with 1 mmol L⁻¹ benzylaminopurine (BAP) or water (control) prior to storage at 5 °C for 0, 13 or 25 days. Quality was assessed upon removal from cold storage as well as after a 2 day shelf-life period at 20 °C. CK-treated fruit showed slower deterioration and dehydration and remained firmer than the control. BAP sprays did not affect color, respiration or sugar-acid balance. The treatments prevented phenolic compound accumulation, and decreased pectin solubilization. By the end of the storage period BAP-treated squash had higher levels (45%) of tightly-bound polyuronides than untreated controls, indicating a substantial delay in cell wall dismantling. CK sprays also reduced neutral sugar solubilization from pectin-rich fractions, but no changes were found in the cross-linking glycans or cellulose. To our knowledge, this is the first work showing that CK can regulate pectin disassembly in developing fruit. Postharvest BAP sprays preventing texture deterioration may be a simple treatment to complement refrigeration of round, soft rind, summer squash.