石榴果汁花青素的稳定性及其护色工艺研究

研究了石榴果汁花青素在不同条件下的稳定性,并进行了石榴果汁的护色实验。结果表明,石榴果汁花青素在酸性条件下有较好的稳定性;温度、磷酸盐、甜味剂对石榴果汁花青素的稳定性影响不显著;Fe3+,Cu2+能引起花青素的较大损失;在石榴果汁中加入0.4%柠檬酸和0.01%抗坏血酸,可保持稳定的玫瑰红色。      

Study on the development of pomegranate juice processing technology: clarification of pomegranate juice

The effects of clarification agents and methods on pomegranate juice quality were studied. Fruits were pressed as whole, and extracted juice was clarified with gelatin, polyvinylypolypyrrolidone (PVPP) and natural sedimentation. In order to determine the effects of these clarifying techniques on product quality, pH, total phenolic substances (TPS), anthocyanin, turbidity, and total colour density tests were applied to each sample. In clarification, the main purpose was to reduce the amount of phenolic substances. Phenolic substances were controlled in each clarification method. The most effective method was the application of 1 g/L gelatine for clarification. Sensory evaluation also applied for clarified juices and gelatin application was selected by panelists to be superior.     

石榴榨汁方法及其护色工艺研究

石榴的榨汁和护色在石榴汁生产过程中是很重要的工序,直接影响出汁率和产品的品质。对石榴的榨汁和护色方法进行研究表明,剥皮压榨石榴的出汁率和品质明显高于带皮压榨石榴,复合护色剂的护色效果高于单一护色剂,复合护色剂的最佳添加量为0.4g/100g柠檬酸和0.01g/100gVc,石榴汁自然澄清最佳时间为3h。     

石榴汁护色工艺

筛选石榴汁护色剂并确定护色工艺参数。通过单因素和正交实验,结合灭菌方法对比和评价护色剂对石榴汁色泽的影响,获得最佳石榴汁护色剂的工艺参数。结果表明,使用复合护色剂的护色效果优于单一护色剂,复合护色剂的最佳配比为1.0g/L氯化钠、0.6g/L焦磷酸钠、1.0g/L柠檬酸、0.2g/L维生素C。     

保健型石榴清汁饮料的研制

水果中的佳品石榴,种植广泛,营养丰富,石榴的保健功能显著。经榨汁、澄清处理后,加入双歧因子(异麦芽低聚糖)、蜂蜜等经科学调配后,酸甜适口,清澈透明无沉淀,是一种具有开发潜力的新型保健饮料。     

浓缩石榴汁流变特性研究

研究了不同浓度的石榴汁在不同温度下的流变特性。结果表明:在实验范围内,石榴汁表现为胀塑性流体,通过回归分析,温度对表观粘度的影响可以用Arrhenius方程表示,浓度对表观粘度的影响可以用指数方程更好地表示,并推导出温度和浓度对表观粘度综合影响的方程式。该方程的建立可以用来预测实际加工过程中一定温度和浓度时石榴汁的表观粘度。      

酶法澄清石榴果汁的研究

探讨了果胶酶添加量、温度、时间、果汁稀释倍数对石榴汁澄清的影响,在单一因素基础上,果胶酶用量1830￣2550U/mL、酶促反应温度为40￣55℃、澄清时间1.5￣2.5h、稀释倍数0￣5,透光率达59.1%。进行正交实验确定最佳条件,结果表明:石榴果汁中果胶酶用量1830U/mL、澄清时间2h、温度50℃、稀释倍数0,可达到最好的澄清效果。     

怀远石榴果汁饮料加工技术研究

以安徽省蚌埠市怀远县出产的石榴为原料,研究石榴果汁饮料的加工技术,确定了工艺流程、产品配方和最佳工艺参数.结果表明:采用浓度为30%的石榴原汁,8%的白砂糖,0.15%的柠檬酸,2.0%的蜂蜜,0.13%Vc,0.10%黄原胶+0.10%CMC,0.05%的山梨酸钾为配方加工出的石榴果汁,风味最佳.最佳工艺参数为Vc打浆前加入,离心速度为4 000 r/min,离心10 min.     

Spray-drying microencapsulation of pomegranate juice increases its antioxidant activity after in vitro digestion

Most of the work on pomegranate antioxidant and antibacterial activity has been carried out with solvent extracts of different plant or fruit parts. Biosensitive compounds in juice may be subject to oxidation, reducing their biological activities. Microencapsulation can be used to protect compounds, allowing its incorporation into functional foods. This study aimed at investigating antioxidant activity after in vitro digestion of microencapsulated juice. Pomegranate juice was encapsulated by spray drying its maltodextrin and gum arabic. The average diameter of the microcapsules was 10–50 µm. We evaluated the bioaccessibility of microencapsulated phenolic compounds by using an in vitro enzymatic digestion. The total phenolic content in digested microencapsulated juice was three times greater than in undigested, indicating that the compounds were made bioaccessible. Digestion also increased antioxidant activity, as measured by ABTS●+ or by DPPH●. Additionally, microencapsulated pomegranate juice showed antibacterial activity against the nine bacteria species tested.     

Identification of odour-active compounds of pasteurised orange juice using multidimensional gas chromatography techniques

Odour-active compounds present in pasteurised orange juice were identified by gas chromatography–olfactometry (GC–O) employing heart-cut multidimensional GC techniques with olfactometry (O) and mass spectrometry (H/C MDGC–O/MS) and comprehensive two-dimensional gas chromatography–accurate mass time-of-flight MS (GC × GC–accTOFMS). Headspace solid phase microextraction sampling proved to be qualitatively adequate for the analysis of pasteurised orange juice. The GC–O approach distinguished 13 potent odour regions (detection frequency ≥ 3) in the orange juice extract, in which 7 regions were then subjected to detailed identification of the compounds that contribute to the odour, by using higher resolution H/C MDGC–O/MS. This analysis permitted the odour-active peaks to be better resolved on the ²D column, with removal from background matrix, for the seven regions. GC × GC–FID and GC × GC–accTOFMS reveal the overall complexity of the volatile compounds in the product and assisted in assignment of the isolated peaks of the odour-active compounds, confirming the identification in a number of cases. Four aldehydes (hexanal, heptanal, octanal, citral), 2 esters (ethyl butanoate, methyl hexanoate), and 4 monoterpenes (α-pinene, D-limonene, linalool, α-terpineol) were confirmed in accordance with olfactometry assessment in the processed juice. This multi-assessment instrument approach of GC–O, GC × GC, and H/C MDGC provided an effective insight into the processed orange juice aroma.     

Chemical composition of juice and seeds of pomegranate fruit

The edible parts of pomegranate fruit represented 52% of total fruit weight, comprising 78% juice and 22% seeds. The fresh juice contained 85.4% moisture, 10.6% total sugars, 1.4% pectin, 0.1 g/100 ml total acidity (as citric acid), 0.7 mg/100 ml ascorbic acid, 19.6 mg/100 ml free amino nitrogen and 0.05 g/100 ml ash. Meanwhile, the seeds are a rich source of total lipids, protein, crude fibers and ash representing 27.2, 13.2, 35.3 and 2.0%, respectively, and also contained 6.0% pectin and 4.7% total sugars. The iron, cupper, sodium, magnesium and zinc contents of the juice were lower than those of seeds, except potassium which was 49.2 ppm in the juice. On the other hand, the physical and chemical properties of seed's lipids indicated that the refractive index was 1.518, melting point 13.0°C, iodine value 74.2, acid number 1.1, unsaponifiable matters 0.7%, saponification value 188.9, ester value 187.8 and glycerol content 10.3%. Moreover, the studied lipids contained 11 fatty acids, from them caprylic, the predominant acid, represented 36.3%, followed by stearic acid (22.5%). Furthermore, oleic and linoleic acids covered 5.1% and 10.3%, respectively. Otherwise, the saturated fatty acids of seed's lipids of pomegranate composed 83.6% of the total fatty acids content.     

Authentication of sweetness of mango juice using Fourier transform infrared-attenuated total reflection spectroscopy

Fourier transform infrared spectrometer equipped with attenuated total reflection and chemometrics were used to determine added sugar content (ASC), total soluble solids (TSS) and real juice content (RJC) in fresh and commercial mango juice. Sucrose solutions (0-27%), fresh mango juice adulterated with 0-27% sucrose, and two commercial brands were evaluated in wavenumber range of 4000-650 cm⁻¹. Partial least squares (PLS) discrimination and principal component analysis (PCA) were used to classify the samples with or without ASC. PLS and multiple linear regression (MLR) were carried out with and without data treatments. The detection limit for ASC was 3% for samples with low natural TSS, 5% for samples with natural TSS more than 10% and 3.6% for commercial samples. ASC, TSS, and RJC were predicted in the wavenumber range of 1476-912 cm⁻¹ using PLS (multiple correlation coefficient, R = 0.99) and three wavenumbers (1088, 1050, 991 cm⁻¹) using MLR (R = 0.98).     

石榴汁膜除菌工艺研究

以新疆和田酸石榴为原料制作石榴汁,用不同孔径的陶瓷膜对石榴汁进行除菌过滤,对比不同孔径膜的膜通量、除菌效率、成分截留率等参数,确定适于石榴汁膜除菌的膜孔径;并研究了石榴汁陶瓷膜除菌最佳工艺。结果表明,用于石榴汁除菌陶瓷膜的孔径为0.22μm;最佳工艺参数为压力0.20MPa、温度20℃。通过陶瓷膜过滤,可以有效去除石榴汁中的悬浮物和有害微生物,同时保留了其中的营养成分,避免了加热杀菌过程中的褐变、营养成分损失等问题。     

RP-HPLC法测定石榴汁中鞣花酸的含量

目的:建立检测石榴汁中鞣花酸的含量测定方法。方法;采用高效液相色谱法,ArcusEP-C18(250mm×4.6mm,5μm)色谱柱,以甲醇-0.1%TFA为流动相梯度洗脱,流速1.0mL/min,检测波长254nm。结果:鞣花酸0.004～0.064μg之间线性关系良好,平均加样回收率为99.32%。结论:方法精密可靠,可作为检测石榴汁中鞣花酸含量的方法。     

石榴汁花青素的制备与稳定性研究

研究了石榴汁花青素的稳定性，结果表明：石榴汁花青素的最大吸收波长λmax=516nm；温度对该色素有一定的降解作用，在加工中热处理温度应不高于60℃;pH对该色素的影响明显，宜在酸性食品中应用；柠檬酸对该色素有一定的增色作用；蔗糖、葡萄糖、紫外光照射对该色素影响作用很小；低浓度的苯甲酸钠和山梨酸钾对该色素无影响，高浓度的则有降解作用；而H2O2、Na2SO3、VC和O3则对该色素有破坏作用。     

Changes in blocking mechanisms during membrane processing of pomegranate juice

The effect of pressure, velocity, pretreatment, membrane type and pore size on fouling mechanisms were evaluated. Pomegranate juice was treated with polyvinylidene fluoride (PVDF) 0.22 μm and mixed cellulose ester (MCE) 0.1 μm at different pressures. Cake formation which was the dominant mechanism was formed in the first stages of process and, as the filtration proceeded, intermediate, standard, and complete blocking, respectively occurred at higher pressure (5 kPa). At lower pressure (0.5 kPa) the last mechanism did not occur. Results showed that cake formation was the only mechanism in MCE 0.22 μm, however, others occurred with MCE 0.1 μm and PVDF 0.22 μm. Using MCE 0.22 μm prior to MCE 0.025 μm can reduce the role of cake formation in pore blocking. Evaluation of the impact of velocity showed that at the higher velocity (0.53 m s⁻¹) the complete blocking occurred faster than at the lower velocity (0.09 m s⁻¹).