The effect of commercial enzyme preparation-assisted maceration on the yield, quality, and bioactivity of essential oil from waste carrot seeds (

Effect of Solid-State Fermentation on the Essential Oil Yield of Curcuma longa Residues

ABSTRACT

The solid waste of Curcuma longa rhizomes generated after its cold juice process making is mostly unused and discarded even though they can contain essential oil. Conventional techniques such as hydrodistillation can be used to extract essential oil, but this generally results in low essential oil yield and inefficient extraction time. Solid-state fermentation as a pretreatment of distillation could improve the yield of essential oil. In this study, we evaluated the effect of solid state fermentation on the yield of extraction of Curcuma longa solid wastes essential oil. The solid-state fermentation was carried out naturally without any addition of inoculum and the extraction was performed by hydrodistillation. Under experimental conditions at room temperature ( 25 ∘ C ) with a moisture content of 44% and anaerobically in the dark, the treatment of 7 days of solid state fermentation followed by 2 h of hydrodistillation provided the highest yield of 1.21% as compared to non-fermented of 0.35% and of 0.96% relative to the raw plant material representing an increase of 71% and 21% respectively. A set of experiments was then carried out by a Doehlert matrix to optimize the yield of extraction. Two independent variables, namely the distillation time and the fermentation time, were studied. Under optimal experimental conditions of 10 days and 4 h, a yield of 1.96% was obtained validating the statistical model. The solid state fermentation applied before the hydrodistillation step has been successful and proves its potential to improve the efficiency of essential oil extraction.

Preparation and Characterization of Antioxidant Peptides from Carrot Seed Protein

Carrot is a very popular vegetable and used for culinary and cosmetic purposes. Carrot seeds can be used for treatment of hangovers and stimulating menstruation. In the present study, the carrot seed protein (CSP) extracted from carrot seed (Daucus carota L.) was hydrolysed by four proteases (papain, trypsin, neutrase, and alcalase). Alcalase hydrolysate exhibited the strongest DPPH radical-scavenging activity (DRSA). The optimum hydrolysis condition for the antioxidant peptide production from CSP was obtained using response surface methodology (RSM). The optimum condition was as follows: hydrolysis time of 3.50 h, substrate concentration of 52.8 g/L, and protease dosage of 419.36 U/g, under which DRSA of 82.46% at 2 mg/mL was obtained. The carrot seed protein hydrolysates (CSPHs) were separated using size exclusion chromatography in order to obtain peptides with stronger antioxidant activity. The hydrolysates were fractionated into four peaks, and fractions F3 and F4 with smaller molecular weight showed stronger antioxidant activity. These findings indicated that the success of RSM in optimizing the hydrolysis conditions and the further work in separation of antioxidant peptides in CSPH is feasible. The CSPH exhibites good antioxidant properties and can be used as useful ingredient in foods.

Generation of bioactive peptides during food processing

Large amounts of peptides are naturally generated in foods through the proteolysis phenomena taking place during processing. Such proteolysis is carried out either by endogenous enzymes in ripened foods or by the combined action of endogenous and microbial enzymes when fermented. Food proteins can also be isolated and hydrolysed by peptidases to produce hydrolysates. endo-peptidases act first followed by the successive action of exo-peptidases (mainly, tri- and di-peptidylpeptidases, aminopeptidases and carboxypeptidases). The generated peptides may be further hydrolysed through the gastrointestinal digestion resulting in a pool of peptides with different sequences and lengths, some of them with relevant bioactivity. However, these peptides should be absorbed intact through the intestinal barrier and reach the blood stream to exert their physiological action. This manuscript is reporting the enzymatic routes and strategies followed for the generation of bioactive peptides.