Effect of ultrasound assisted extraction upon the Genistin and Daidzin contents of resultant soymilk

Antioxidative Properties of Fermented Soymilk Using Lactiplantibacillus plantarum LP95

In recent times, there has been a growing consumer interest in replacing animal foods with alternative plant-based products. Starting from this assumption, for its functional properties, soymilk fermented with lactic acid bacteria is gaining an important position in the food industry. In the present study, soymilk was fermented with Lactiplantibacillus plantarum LP95 at 37 °C, without the use of stabilizers as well as thickeners and acidity regulators. We evaluated the antioxidant capacity of fermented soymilk along with its enrichment in aglycone isoflavones. The conversion of isoflavone glucosides to aglycones (genistein, glycitein, and daidzein) was analyzed together with antioxidant activity (ABTS) measurements, lipid peroxidation measurements obtained by a thiobarbituric acid reactive substance (TBARS) assay, and apparent viscosity measurements. From these investigations, soymilk fermentation using Lp. plantarum LP95 as a starter significantly increased isoflavones' transformation to their aglycone forms. The content of daidzein, glycitein, and genistein increased after 24 h of fermentation, reaching levels of 48.45 ± 1.30, 5.10 ± 0.16, and 56.35 ± 1.02 μmol/100 g of dry weight, respectively. Furthermore, the antioxidant activity increased after 6 h with a reduction in MDA (malondialdehyde). The apparent viscosity was found to increase after 24 h of fermentation, while it slightly decreased, starting from 21 days of storage. Based on this evidence, Lp. plantarum LP95 appears to be a promising candidate as a starter for fermented soymilk production.

Generation of garlic flavor after frying by infusing alliin into potato strips using pulsed electric field and assisted infusion methods

A new method of alliin infusion into potato strips to generate garlic flavor upon frying was investigated. Potato strips were treated using pulsed electric field (PEF) and then allin was infused into the treated strips using immersion, ultrasound, or vacuum assisted infusion. Results showed that under lower PEF intensities (0.250, 0.650 and 1.250 kJ/kg), assisted infusion methods significantly improve alliin infusion efficiency (p < 0.05). The kinetics for alliin infusion showed that 1.250 kJ/kg PEF treatment and 35 kHz ultrasound assisted infusion have the highest a values of 94.69 and 94.80 (mg/mL^.h), respectively. Scanning electron microscope (SEM) highlighted different cell structural changes before and after being treated with different PEF intensities and infusion methods. Sensory evaluations confirmed generation of garlic flavor upon frying (p < 0.05).

Impact of Pulsed Electric Field Pre-Treatment on the Isoflavone Profile of Soymilk

In this study, pulsed electric fields (PEFs) were evaluated as extraction-aiding technology during soymilk manufacturing to improve its isoflavone profile. Low-intensity PEFs were applied at different processing conditions in two stages of the soymilk extraction process, hydrated soybeans (HSB) and soybean slurry (SBS), with the soymilk extracted from the conventional process as control (CSM). Overall, resultant soymilk samples from PEF-HSB and PEF-SBS presented lower concentrations of glucosides isoflavones and greater aglycone content than those in CSM. In contrast to genistin (Gin) and daidzin (Din), which decreased around 18.5–52.6% and 10.9–54.6%, respectively, an increase in genistein (Ge, 12.3–64.4%) and daidzein (Da, 9–55.8%) was observed. The total isoflavone content (TIC) of most soymilk samples prepared from PEF-HSB was lower than that of the CSM. Conversely, when PEF-SBS was used, the TIC of resultant soymilk was not significantly affected or slightly decreased. However, PEF treated HSB at 10 kVcm−1/100 pulses and SBS at 6 kVcm−1/10 pulses led to a significant augment in TIC, of up to 109 ± 2.39 and 110 ± 1.26 μg/g, respectively, in the extracted soymilk samples. These results indicated that low-intensity PEF is a potential technology that could be implemented during soymilk manufacturing processing to modify the isoflavone profile and content of soymilk, mainly increasing its aglycone concentration.

Novel Extraction Method Using Excipients to Enhance Yield of Genistein and Daidzein in Trifolium pratensis L

Isoflavones can be found in different chemical forms, but the health beneficial effects mainly appear in their free forms—aglycones. Their yield in red clover (Trifolium pratensis L.) extracts differs due to different extraction and hydrolysis methodologies. The main aim of this study was to obtain the highest yields of daidzein and genistein from red clover blossoms through the various extraction and hydrolysis methods and to increase their quantities using additional excipients. Extracts were obtained by ultrasound-assisted, heat-reflux and maceration methods combining them with acidic, alkaline, and thermal hydrolysis. Using ultrasound-assisted extraction with optimal conditions and heat-reflux method highest yields of isoflavones were obtained in UTE510 (393.23 ± 19.66 µg/g daidzein and 171.57 ± 8.58 µg/g genistein); UTE530 (415.07 ± 20.75 µg/g daidzein and 150.57 ± 7.53 µg/g genistein) and HNE5 (432.30 ± 21.61 µg/g daidzein and 154.50 ± 7.72 µg/g genistein) samples. These conditions were used with excipients: magnesium aluminometasilicate, croscarmellose sodium, sodium carboxymethyl starch and vinylpyrrolidone-vinyl acetate copolymer. This is the first study reporting the ability of the vinylpyrrolidone-vinyl acetate copolymer to promote solubilization and availability of active compounds from a herbal extract, resulting in enhanced isoflavones yield. The results of the present study showing increased solubility and availability provided by the vinylpyrrolidone-vinyl acetate copolymer suggest that this preparation could in principle also reduce variability due to limited water solubility of isoflavones.

High-power ultrasound as pre-treatment in different stages of soymilk manufacturing process to increase the isoflavone content

Ultrasound (US) was applied as a pre-treatment in hydrated soybeans (HSB) and soybean slurry (SBS) during soymilk elaboration process to evaluate the feasibility of increasing the isoflavone content (IC) in the resultant soymilk. A predictive model and optimum US processing conditions were obtained by response surface methodology (RSM) using a three-level-three-factor Box-Behnken statistical design (BBD) in which US amplitude (50, 75, and 100%), temperature (30, 45, and 60 °C), and time (20, 40, and 60 min) were selected as independent variables. Most of the US treatments applied in the HSB or SBS caused a significant increase (3-62%) in the total IC of the obtained soymilks over the control soymilk (6.97 mg/100 mL). However, the IC of the resultant soymilks from sonicated HSB (11.38 mg/100 mL) was significantly higher than that in soymilk prepared from US-treated SBS (8.66 mg/100 mL). Experimental data were fitted into a 2nd-order-polynomial model and processing parameters were optimized (100% amplitude, 30 °C, 20 min) to get the highest predicted and experimental IC, 11.38 and 12.8 mg/100 mL, respectively. These results indicated that US is a potential technology that could be implemented during soymilk manufacturing processing as pre-treatment of HSB to obtain soymilk with high isoflavone content and consequently better functionality.

The isoflavone content of two new alfalfa-derived products for instant beverage preparation

The frequent use of plant-based products to promote health leads to the search for scientific information related to efficacy and safety of those products for human consumption. Two alfalfa-derived products (ADP), freeze-dried juice (FDJ) and dehydrated powder (DP), from alfalfa harvested in Mexico, are being developed as new possible nutraceuticals. To the best of our knowledge, any study reports the real composition of such products used to prepare instant beverages in what concerns isoflavone contents. Seven isoflavones (glycitein, formononetin, biochanin A, daidzein, genistein, daidzin and genistin) were assessed by HPLC-DAD analysis as well as its variation in five different batches of these products. Different solvents were tested in order to choose the best one to extract isoflavones. The results showed the presence of daidzein, genistein, genistin and daidzin in most samples while glycitein, formononetin and biochanin A were not detected. Significant differences between isoflavone contents were found with different solvent systems. Water was the best option to extract daidzein (0.40-1.08 mg per unit and 1.30-4.90 mg per unit for DP and FDJ, respectively) whereas the water-methanol-formic acid mixture was efficient to extract genistein (0.19-0.43 mg per unit and 0.15-0.72 mg per unit for DP and FDJ, respectively). In all cases, the total isoflavone content was higher in freeze-dried juices than in dehydrated powders. Genistein and daidzein were the more abundant isoflavones quantified. Further physiological and nutritional studies are needed to complete the validation of effectiveness and safety of these products.