Phanuphong Chaiwut

Extraction of bromelain from pineapple peels

Large amount of pineapple peels (by-products) is left over after processing and they are a potential source for bromelain extraction. Distilled water (DI), DI containing cysteine and ethylenediaminetetraacetic acid (EDTA) (DI-CE), sodium phosphate buffer pH 7.0 (PB) and PB containing cysteine and EDTA (PB-CE) were used as extractants for bromelain from the pineapple peels. The highest bromelain activity was obtained when it was extracted with PB-CE (867 and 1032 units for Nang Lae and Phu Lae cultv, respectively). The PB could maintain the pH of the extract (pH 5.1—5.7) when compared with others. Under sodium dodecyl sulfate polyacrylamide gel electrophoresis, the extract showed protein bands in the range 24—28 kDa. The protein band with a molecular weight of ∼28 kDa exposed the clear zone on blue background under the casein-substrate gel electrophoresis. The effects of the bromelain extract on the protein patterns of beef, chicken and squid muscles were also determined. Trichloroacetic acid soluble peptide content of all the treated muscles increased when the amount of bromelain extract increased. Decrease in myosin heavy chains and actin was observed in all the muscle types when bromelain extract was used. The best extractant for bromelain from pineapple peels was PB-CE. Moreover, bromelain extract could be used as a muscle food tenderizing agent in food industries.

Use of Response Surface Methodology for Phenolic Antioxidant Extraction from Lotus (Nelumbo nucifera Gaertn.) Pod Pericarp

The pod of lotus (Nelumbo nucifera Gaertn.) was value-added by using as raw material for phenolic antioxidant extraction using conventional shaking method. The pericarp part of lotus pod gave the significantly highest values of extractable phenolic content (EPC), flavonoid content and DPPH radical scavenging activity which were equal to 27.15±1.74 mg gallic acid equivalent (GAE)/g dry weight (dw), 0.59±0.04 mg quercetin equivalent (QE)/g dw and 0.65±0.02 mg trolox equivalent antioxidant capacity (TEAC)/g dw, respectively. Response surface methodology (RSM) was further employed to optimize the extraction conditions of phenolic antioxidant from the pod pericarp. Three independent variables, i.e., ethanol concentration (X1), shaking speed (X2) and extraction time (X3) were investigated through two responses of EPC and DPPH radical scavenging activity. The statistical analysis indicates that the three variables and the contribution of quadratic model had significant influence on the all responses (P<0.05). The optimum extraction condition was provided as follows: ethanol concentration 77.6%, shaking speed 223.4 rpm and extraction time 5.2 h. Under the optimized condition, the predicted values of EPC and DPPH radical scavenging activity were 30.00 mg GAE/g dw and 0.74 mg TEAC/g dw, respectively. This could be hence applied in industrial phenolic antioxidant extraction of inedible pericarp of lotus pod.