Optimisation of antioxidant extraction from Solanum tuberosum potato peel waste by surface response methodology

Effects of temperature, time, and solvent ratio on the extraction of phenolic compounds and the anti-radical activity of Clinacanthus nutans Lindau leaves by response surface methodology

Background

Clinacanthus nutans Lindau is a well-known plant, native to tropical Asian countries. Reports on this plant that is rich in phenolic compounds have focused on its therapeutic anti-inflammatory, anti-herpes simplex, antioxidant, and anti-cancer characteristics. In this paper, the influence of the extraction parameters—temperatures (60–80 °C), times (80–120 min), and solvent ratios (70:30–90:10) of water:ethanol were investigated using response surface methodology in order to determine the optimum extraction conditions that could produce maximum extraction yields of the phenolic compounds and the highest anti-radical activity of the C. nutans extract.

Results

The optimum conditions suggested by the predicted model were: an extraction temperature of 60 °C, an extraction time of 120 min and a water:ethanol solvent ratio of 90:10 v/v%. The residual standard error of 0.2% indicated that there was no significant difference between the actual and predicted values and it proved that the models were adequate to predict the relevant responses. All the independent variables had a significant effect (p < 0.05) on all the responses which indicated that all extraction parameters employed in this study were important in the optimization process. The R² values for three responses, extraction yields, DPPH radical scavenging activity and TPC were 0.9999, 0.9999 and 0.9983 respectively, suggesting that the quadratic polynomial models developed were satisfactorily accurate to be used in analyzing the interactions of the parameters (response and independent variables).

Conclusion

This study could be useful in the development of cosmeceutical products containing extracts of C. nutans.

Optimisation of Pueraria isoflavonoids by response surface methodology using ultrasonic-assisted extraction

Puerariae Lobatae Radix (PLR) exerts cyto-protective effect against oxidative stress due to its high isoflavonoid content. In this study, the ultrasonic-assisted extraction condition for the maximum recovery of isoflavonoids with high cyto-protective effect was optimised by response surface methodology (RSM). A second-order polynomial fitted the experimental data (R²: 0.9736; p-value <0.0001). The optimal extraction parameters were determined as: extraction time 16.02min, ethanol concentration 41.41% and liquid-to-solid ratio 44.35mL/g. Practical experiments with extraction time 16.00min, ethanol concentration 41.00% and liquid-to-solid ratio 44.00mL/g were carried out in triplicate. This subsequently yielded a cell viability of 82.90±0.78% against hydrogen peroxide-induced oxidative stress on EA.hy926, and was comparable to the predicted of 85.60%. Five chemical constituents in the extract were identified to exert cyto-protective effect. Taken together, this method successfully integrated RSM and the partial least squares regression method to optimise the PLR extract with highest cyto-protective activity.

Side Streams of Plant Food Processing As a Source of Valuable Compounds: Selected Examples

Industrial processing of plant-derived raw materials generates enormous amounts of by-products. On one hand, these by-products constitute a serious disposal issue because they often emerge seasonally and are prone to microbial decay. On the other hand, they are an abundant source of valuable compounds, in particular secondary plant metabolites and cell wall materials, which may be recovered and used to functionalize foods and replace synthetic additives with ingredients of natural origin. This review covers 150 references and presents select studies performed between 2001 and 2016 on the recovery, characterization, and application of valuable constituents from grape pomace, apple pomace, potato peels, tomato pomace, carrot pomace, onion peels, by-products of citrus, mango, banana, and pineapple processing, side streams of olive oil production, and cereal by-products. The criteria used were economic importance, amounts generated, relevance of side streams as a source of valuable compounds, and reviews already published. Despite a plethora of studies carried out on the utilization of side streams, relatively few processes have yet found industrial application.

Phenolic Compounds in the Potato and Its Byproducts: An Overview

The potato (Solanum tuberosum L.) is a tuber that is largely used for food and is a source of different bioactive compounds such as starch, dietary fiber, amino acids, minerals, vitamins, and phenolic compounds. Phenolic compounds are synthetized by the potato plant as a protection response from bacteria, fungi, viruses, and insects. Several works showed that these potato compounds exhibited health-promoting effects in humans. However, the use of the potato in the food industry submits this vegetable to different processes that can alter the phenolic content. Moreover, many of these compounds with high bioactivity are located in the potato's skin, and so are eliminated as waste. In this review the most recent articles dealing with phenolic compounds in the potato and potato byproducts, along with the effects of harvesting, post-harvest, and technological processes, have been reviewed. Briefly, the phenolic composition, main extraction, and determination methods have been described. In addition, the "alternative" food uses and healthy properties of potato phenolic compounds have been addressed.