Functional properties of sonicated and non-sonicated extracted leaf protein concentrate from Diplazium esculentum

Leaf protein concentrate of edible fern Diplazium esculentum was extracted using sonication and non-sonication methods and its functional properties were evaluated. The leaf protein concentrate contained 34.28 and 9.89% protein for sonicated and non-sonicated extractions, respectively. Sonication yielded (36.36%) better emulsion activity over non-sonication (31.10%). Foaming capacity was also found better in sonication (7.27%) over non-sonication (6.99%), and oil absorption capacity also improved in sonication (7.55 g of oil/g) over its counterpart (7.41 g of oil/g). Contact angle experiments with the leaf protein concentrate evidenced the enhancement of more hydrophilicity of the sonicated sample. Thermal properties of the leaf protein concentrate with sonication evidenced more stability (55.58 and 95.95°C) over the non-sonicated (46.75 and 75.60°C). Fourier transform infrared spectral analysis with the leaf protein concentrate of Diplazium esculentum was used to assess the secondary structural data such as α-helix and β-sheets. The various percentages of secondary structures of protein in sonicated and non-sonicated samples were 49.06 and 69.16% for α-helix, 33.59% and 17.02% for β-sheet and 42.02 and 35.68% for turn, respectively. The results of the present investigation showed credible evidence to support that sonication method of extraction of leaf protein concentrate was better in terms of protein yield and functional properties as compared to the non-sonication. The sonicated extracted leaf protein concentrate has the potential for developing value added products.     

活性炭吸附原子吸收光度法测定铅锑精矿中金的含量

通过在铅锑精矿焙烧时加入一定量的氧化锌或氧化钙，使铅锑精矿在灼烧过程中的单质硫、有机质、硫化物、碳充分焙烧，然后采用王水分解矿样，活性炭动态吸附富集金，灰化除碳，王水溶解，原子吸收光度法测定铅锑精矿中金含量，方法快速、准确，同时适用于含碳、硫较高焙烧时易结块的精矿样品。     

Chitosan coatings enriched with active shrimp waste for shrimp preservation

An active coating solution composed of chitosan (Ch) and a shrimp protein-lipid concentrate (PCc), both obtained from Litopenaeus vannamei processing wastes, was applied to preserve shrimp during chilled storage. The addition of PCc increased the antioxidant capacity of the Ch coating, yielding a lower-viscosity mixture which, however, was viscous enough to adhere to the shrimp while maintaining its activity. The shrimp storage trial showed that the Ch coatings, especially when enriched with PCc (Ch-PCc), delayed microbial growth, mainly by extending the lag phase. Pseudomonas spp. appeared to be the predominant bacteria in the microbiota. H₂S-producing organisms and luminescent colonies were especially sensitive to this active coating, with inhibition greater than 4 and 2 log cycle respectively, while the growth of lactic acid bacteria was not favored. The Ch-PCc coating delayed the onset of melanosis and did not confer any sensorially detectable color, taste or odor. It therefore shows promise as a means to improve the quality of shrimp during cold storage.     

Anthocyanin profile of red fruits and black carrot juices,purees and concentrates by HPLC‐DAD‐ESI/MS‐QTOF

A fast and reliable method for anthocyanin extraction and identification by HPLC‐DAD‐ESI/MS‐QTOF was used to analyse the anthocyanin composition of commercial red fruit juices (blackberry, redcurrant and pomegranate), purees (strawberry, cherry and raspberry) and concentrates (elderberry, blueberry and red grape). The anthocyanin profile of black carrot juice is also reported. The extraction and analysis method allowed us to detect and quantify a wide range of individual anthocyanins in a simple and rapid way. Pelargonidin‐3‐glucoside was detected in redcurrant for the first time and petunidin‐3‐galactoside quantified for the first time in blueberries. Considering the health benefits that have been associated with anthocyanin consumption, all these fruit and vegetables processed products could appear as a good source of this group of phytochemical compounds for their direct consumption or their use as ingredients for the design of new food product or food supplements.     

Influence of pH on colour and iron content of peptide fractions obtained from bovine Hb concentrate hydrolysates

The effect of pH on colour and iron content (Fe) of peptide fractions obtained from bovine haemoglobin concentrate (BHC) hydrolysates was studied. Four hydrolysates were obtained using three enzymes: Protex‐6‐L (P), Fungal–Protease–Concetrate (FC) and Flavourzyme (F). BHC and its hydrolysates (P, FC, P + F, FC + F) were fractioned at pH 4.5, 7.0 and 9.5. Solubility and Fe from different fractions were measured. Correlations between CIELAB colour parameters and Fe from different fractions were analysed. The colour from different fractions varied from red to yellow (a* and b* positives). Lightness values (L*) ranged from twenty‐four to seventy. FC4.5 and FC + F4.5 fractions were the clearest and yellow (higher L*, b*, h), while BHC9.5 and P + F9.5 fractions had the lowest values of L*, b* and h. There was an inverse linear relationship between b* and L* parameters and Fe from fractions. This relationship could be associated with the pH of extraction. As pH increases Fe significantly increases and lower b* and L* values were obtained.     

Effect of freezing on the viscoelastic behaviour of whey protein concentrate suspensions

The effect of freezing on viscoelastic behaviour of whey protein concentrate (WPC) suspensions was studied. Suspensions with total protein content of 5% and 9% w/v were prepared from a commercial WPC (unheated suspensions). A group of unheated suspensions was treated at two temperatures (72.5 and 77.5 °C) during selected times to obtain 60% of soluble protein aggregates (heat-treated suspensions). Unheated suspensions and heat-treated suspensions were frozen at −25 °C (frozen unheated and frozen heat-treated suspensions). Frequency sweeps (0.01–10 Hz) were performed in the region of linear viscoelasticity at 10, 20, 30, 40, and 50 °C. Mechanical spectra of all studied suspensions at 20 °C were similar to viscoelastic fluids and complex viscosity increased with the frequency (ω). Elastic (G′) and viscous (G″) moduli were modelled using power law equations (G′ = aω^x, G″ = bω^y), using fitted parameters a, x, b, and y for statistical analysis. Exponent y was the most influenced by freezing, indicating the existence of a higher degree of arrangement in frozen unheated suspensions and a lower degree of arrangement in frozen heat-treated suspensions. Only characteristic relaxation times (inverse of the crossover frequency) of suspensions with 5% w/v of total protein content were significantly influenced by freezing. Time–temperature superposition was satisfactory applied in unheated whey protein concentrate suspensions only in the range of high temperatures (30–50 °C). However, this principle failed over the complete temperature range in most of the frozen suspensions. It is possible that freezing produced an increase in the susceptibility to morphological changes with temperature during the rheological measurements.     

硫精矿提硫降杂工业试验研究

为了降低硫精矿中的杂质，提高硫品位，开展了现场工业试验研究．对硫精矿进行两次开路精选，得到高硫矿和低硫矿两个产品，21个班平均指标是：高硫矿产率39．82％、硫品位37．55％、MgO品位0．582％；低硫矿硫品位28．7l％。针对工业试验存在问题，提出了硫精矿再磨增加单体解离度．进行系统稳定试验，探索旋流器分级提硫的改进方案。     

真空缓冷铸渣机冷却炉渣选铜的研究

介绍了真空缓冷炉渣的工艺矿物学特性。试验研究结果表明，该炉渣属于中等可碎性偏难，硬度系数在８￣１６之间，在磨矿细度为－０．０１６ｍｍ占８９％时，粗、扫选抛尾粗精矿再磨再选，以Ｚ－２００、ＳＮ－９和丁胺为混合捕收剂，最终得到铜精矿产率为４．５９％，精矿含铜２３．４８％，含金５．８ｇ／ｔ，铜回收率为８３．７０％；尾矿含铜０．２２％，含金０．１８ｇ／ｔ。     

用武钢程潮铁精矿生产氧化球团试验研究

以程潮磁铁精矿为原料，膨润土为粘结剂，制作了氧化球团矿。实验研究了铁精矿的造球性能以及氧化球团和的焙烧性能，冶金性能，实验结果表明，程潮铁精矿（-0.074mm颗粒大于71％）的适宜造球条件为：膨润土用量2．5％，水分含量8．5％－9．0％，造球时间30min以上。     

超声波强化草酸浸出氧化锌精矿

研究超声波强化草酸浸出氧化锌精矿过程，在试验条件下，用超声波辐射浸出氧化锌精矿同机械搅拌相比，浸出率提高32.12%；锌浸出率随辐射时间延长而提高；超声波辐射强度提高，辐射时间一定时，浸出率提高，浸出率相同时，浸出时间缩短，液固比小，浸出率低，但液固比过大，会给后续工序带来困难。