The Estimation of Pectin as Calcium Pectate and the Application of this Method to the Determination of the Soluble Pectin in Apples

The Effect of High Voltage Electrical Discharge on the Physicochemical Properties and the Microbiological Safety of Rose Hip Nectars

Although neglected as an industrial raw material, rose hip has been important for both nutritional and medical purposes for centuries. The main goal of this study was to propose a rapid and inexpensive non-thermal technique such as high voltage electrical discharge (HVED) to preserve valuable rose hip bioactive compounds, towards the development of high-quality products, including low-calorie products. The objective of this work was to evaluate the effects of HVED on the physicochemical properties and the microbiological safety of rose hip nectar formulations and, for comparison, on a pasteurised sample. Physicochemical analysis proved that rose hip pulp and the prepared nectars were valuable sources of polyphenols and ascorbic acid with high antioxidant activity. The HVED technique had minimal effects on the quality characteristics of the nectars under the different process conditions (50, 100 Hz; 10, 15, 20 min). In addition, the pasteurised nectar showed the greatest loss of ascorbic acid (54%) and phenolic compounds (40%). The microbiological quality of nectars was examined immediately after preparation/treatment and after 6 and 12 days of storage at 4 °C. In addition to the pasteurised sample, HVED-treated rose hip nectar prepared from microwave-blanched puree with extended shelf life had satisfactory microbiological safety after storage.

A New Method for Determination of Pectin Content Using Spectrophotometry

The study aimed at developing a new spectrophotometric method for determining the pectin content. Take commercial pectin as an example, and the method is based on the reaction of copper ions with pectin to produce copper pectate. The spectrophotometer was used to measure the remaining content of copper ions so as to calculate the pectin content. This method eliminated the weight step and avoided the error associated with it. Effects of reaction time, temperature, and pH on absorbance were also studied. Additionally, the accuracy of this method was verified. It indicated excellent repeatability and accuracy with the relative standard deviation of 2.09%. In addition, three different plant types were used to demonstrate the reliability of the method. To summarize, this method can be widely used for the determination of pectin content in many materials.

Pectic Substance of Cotton Fibres in Relation to Growth

The content of pectic substance in cotton fibres at various stages of growth was determined. The results suggest three distinct stages of de velopment of the fibre. The first extends to about the 18th day and is char acterized by a gradual decrease in the content of pectic substance. The second extends from the 18th to about the 35th day during which time there occurs a rapid decrease in the content of pectic substance. In the final stage, which extends from about the 35th day to maturity, there is only a slight decrease in the content of pectic substance. These three stages of de velopment are in good agreement with those deduced by other investigators from different types of data.

Enzymatic pretreatment of lignocellulosic wastes to improve biogas production

The effect of enzymatic pretreatment of sugar beet pulp and spent hops prior to methane fermentation was determined in this study. These industrial residues were subjected to enzymatic digestion before anaerobic fermentation because of high fiber content (of 85.1% dry matter (DM) and 57.7% DM in sugar beet pulp and spent hops, respectively). Their 24h hydrolysis with a mix of enzymatic preparations Celustar XL and Agropect pomace (3:1, v/v), with endoglucanase, xylanase and pectinase activities, was most effective. Reducing sugars concentrations in hydrolysates of sugar beet pulp and spent hops were by 88.9% and 59.4% higher compared to undigested materials. The highest yield of biogas was obtained from the enzymatic hydrolysate of sugar beet pulp (183.39 mL/d from 1g COD at fermenter loading with organic matter of 5.43 g COD/L × d). Fermentation of sugar beet pulp gave 19% less biogas. Methane fermentation of spent hops hydrolysate yielded 121.47 mL/d biogas from 1g COD (at 6.02 g COD/L × d, 13% more than from spent hops). These results provide evidence that suitable enzymatic pretreatment of lignocellulosic wastes improve biogas yield from anaerobic fermentation.

Effect of pre-storage heat treatment on enzymological changes in peach

Peach (Prunus persica (L.) Batsch) fruit was subjected to hot water and moist hot air treatment at varying temperatures. The activities of polyphenoloxidase (PPO) and polygalacturonase (PG) were monitored during storage for 0, 3 and 6 days. PPO activity decreased in all treatments during storage. This decrease was more in hot water treated fruits than in hot air. PPO activity decreased with the increase in treatment duration. However, the PG activity increased in heat treated fruits as well as control. This increase was more in mild heat treatments as compared to severe heat treatment. Both polyphenol and pectin contents decreased during storage in both heat treatments.

Induction and repression of endopolygalacturonase synthesis by Pyrenochaeta terrestris

Endopolygalacturonase (endo-PG) synthesis was inducible in standing and replacement liquid culture by Pyrenochaeta terrestris. Inducers were galacturonic acid, its polymers (pectin and polypectate), and structural relatives (mucic acid, tartronic acid, and dulcitol). On pectin, fungus growth and endo-PG synthesis were proportional to initial pectin concentration.Synthesis of endo-PG on pectin was stimulated by hexose supplements at 0.005 M and repressed by supplements at 0.05 M and above. Thus, repression of induced endo-PG synthesis was not dominant at low supplement concentrations as was found for induced cellulase synthesis by the same organism. This suggests that the production of endo-PG by the parasite during pathogenesis is less repressed by host sugars than is cellulase synthesis.

A NEW TYPE OF INTERMITTENTLY-IRRIGATED SAND CULTURE EQUIPMENT

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