Development of a microwave‐assisted extraction method for the recovery of bioactive inositols from lettuce (Lactuca sativa) byproducts

Abstract

A microwave-assisted extraction (MAE) method was developed for the extraction of bioactive inositols (D-chiro-and myo-inositols) from lettuce (Lactuca sativa) leaves as a strategy for the revalorization of these agrofood residues. Gas chromatography-mass spectrometry was selected for the simultaneous determination of inositols and sugars (glucose, fructose, and sucrose) in these samples. A Box-Behnken experimental design was used to maximize the extraction of inositols based on the results of single factor tests. Optimal conditions of the extraction process were as follows: liquid-to-solid ratio of 100:1 v/w, 40°C, 30 min extraction time, 20:80 ethanol:water (v/v), and one extraction cycle. When compared with conventional solid-liquid extraction (SLE), MAE was found to be more effective for the extraction of target bioactive carbohydrates (MAE 5.42 mg/g dry sample versus SLE 4.01 mg/g dry sample). Then, MAE methodology was applied to the extraction of inositols from L. sativa leaves of different varieties (var. longifolia, var. capitata and var. crispa). Dchiro-and myo-inositol contents varied between 0.57-7.15 and 0.83-3.48 mg/g dry sample, respectively. Interfering sugars were removed from the extracts using a biotechnological procedure based on the use of Saccharomyces cerevisiae for 24 h. The developed methodology was a good alternative to classical procedures to obtain extracts enriched in inositols from lettuce residues, which could be of interest for the agrofood industry.

Optimizing the Extraction Process of Value-Added Products from Olive Cake Using Neuro-Fuzzy Models

“…Extractions under these conditions led to a significant increase in inositol concentration of up to 70%, i.e., 1126 mg/L (Figure 4). Zuluaga et al [14] obtained inositol from different lettuce types using a microwave-assisted extraction process. The highest inositol concentration (5.42 mg/g dry sample) was obtained using a liquid-solid ratio of 100:1, performing one extraction for 30 min at 40 • C, with an ethanol-water mixture as the solvent.…”

“…For instance, inositol supplements are frequently used to treat anxiety and stress while also exhibiting beneficial effects in other disorders. Despite some authors having reported the extraction of inositol from natural sources, such as mung beans and lettuce [13,14], its potential extraction from olive cake has not been previously studied by other authors. The extraction process was optimized by identifying the most suitable solvent and exploring the influence of the operating variables (i.e., temperature, time, solvent/extract ratio, number of extraction stages, and pH) on the extraction yield.…”

Microwave Assisted Extraction of Bioactive Carbohydrates from Different Morphological Parts of Alfalfa (Medicago sativa L.)

“…Extraction of bioactive carbohydrates from fruits, vegetables, and legumes have been usually carried out by conventional solid-liquid extraction (SLE) [13][14][15][16]. However, there is a growing interest in applying more efficient advanced extraction techniques which help to break vegetable tissues, releasing bioactive compounds from cell structures, as an alternative to the tedious and time-consuming SLE-based processes [17,18]. Among the most outstanding implemented techniques, Microwave Assisted Extraction (MAE) is preferred for its speed, efficiency, and safe operation [16,[18][19][20][21].…”

“…However, there is a growing interest in applying more efficient advanced extraction techniques which help to break vegetable tissues, releasing bioactive compounds from cell structures, as an alternative to the tedious and time-consuming SLE-based processes [17,18]. Among the most outstanding implemented techniques, Microwave Assisted Extraction (MAE) is preferred for its speed, efficiency, and safe operation [16,[18][19][20][21]. During conventional treatments, heat energy is delivered through conduction-convection processes with the consequent loss of heat energy to the environment.…”

“…MAE has been mainly used for the extraction of polysaccharides (i.e., pectins, inulin, etc) from different natural matrices [20,31], although recently its utility for the extraction of bioactive low molecular weight carbohydrates (LMWC) from food residues has been addressed (i.e., lettuce leaves [18], artichoke bracts [20], and legume pods [21]). However, as far as we know, MAE efficiency for the extraction of bioactive carbohydrates from alfalfa has not yet been evaluated.…”