Changes in polyphenolic compounds and antioxidant activities of seed-used pumpkin during hydrothermal treatment

An environmentally friendly physical processing method, hydrothermal treatment (HT), was used to increase the content of specific compounds and antioxidant activities of seed-used pumpkin byproducts. The influence of hydrothermal temperature (80 °C-160 °C) and time (30-150 min) on changes in polyphenols and antioxidation was evaluated. The results revealed that the maximum free polyphenol content (140 °C for 120 min) was 3.96-fold higher than the untreated samples. Elevated temperature and long duration changed phenolic acid contents. For example, p-coumaric acid, rutin and chlorogenic acid exhibited a decreasing trend, and p-hydroxybenzoic acid, quercetin and cinnamic acid showed an increasing trend. Compared to controls, HT was significantly associated with increased antioxidant activities. To comprehensively reveal the influence of hydrothermal temperature and time on changes in polyphenolic content, back propagation artificial neural network (BP-ANN) models with accurate prediction ability were developed, and the results exhibited well-fitted and strong approximation ability (R² > 0.95 and RMSE < 2 %) and stability.

Membrane permeabilizers enhance biofortification of Brassica microgreens by interspecific transfer of metabolites from tea (Camellia sinensis)

Interspecific metabolite transfer (ISMT) is a novel approach for plants biofortification. In this study, the effect of tea (Camellia sinensis; Cs), with or without membrane permeabilizers EDTA and Tween, as a donor plant on broccoli, cauliflower and kale sprouts was investigated. As a result, caffeine- and catechin-enriched broccoli, cauliflower and kale microgreens were produced. Kale sprouts were most permeable for catechins from Cs, while cauliflower was most permeable for caffeine. Cs + EDTA significantly increased vitamin C in broccoli and kale. Among the tested enzymes activity, pancreatic lipase was the most affected by the treatment with broccoli and cauliflower biofortified with Cs or Cs combined with permeabilizers. Broccoli sprouts biofortified with Cs most significantly inhibited α-amylase, while those biofortified with Cs combined with permeabilizers most significantly inhibited α-glucosidase. Results point to ISMT combined with membrane permeabilizers as a promising and eco-friendly biofortification strategy to improve the biopotential of Brassica microgreens.

Novel green production of natural-like vanilla extract from curcuminoids

The demand for natural vanilla extract, and vanillin in particular, by far exceeds the current production, as both the cultivation of vanilla beans and the extraction of vanillin are laborious. For this purpose, most vanillin used today is produced synthetically, contrary to the general trend toward bio-based products. The present study deals with the synthesis of nature-based vanillin, starting with the more accessible rhizomes of the plant Curcuma longa. Besides vanillin, vanillic acid and p-hydroxybenzaldehyde are synthesized that way, which are also found in the natural vanilla bean. The extraction of the curcuminoids and, finally, their conversion to the flavors are performed using visible light and food-grade chemicals only. A binary mixture of ethanol and triacetin, as well as a surfactant-free microemulsion consisting of water, ethanol, and triacetin, are investigated in this context. The results exceed the literature values for Soxhlet extraction of vanilla beans by a factor > 7.

Indoleamine 2,3 dioxygenase 1 immobilization on magnetic nanoparticles for screening inhibitors from coffee

In this study, a ligand fishing method was developed to screen potential indoleamine 2,3-dioxygenase 1 (IDO1) inhibitors from coffee extracts by immobilization of IDO1 enzyme on amino-modified magnetic nanoparticles combined with UHPLC-Q-TOF-MS/MS analysis. Parameters including enzyme concentration, immobilization time, the pH of glutaraldehyde and the amount of magnetic nanoparticles were optimized. The results indicated that immobilized IDO1 could be reused 5 times and was stable during storage for 7 days. Several IDO1 ligands were captured by incubating immobilized IDO1 with coffee extract, of which 10 showed an obvious difference comparing to non-conjugated bare nanoparticles. In vitro inhibitory activity was further performed by CE analysis, in which ferulic acid and chlorogenic acid had better IDO1 inhibitory activity, with IC₅₀ value of 113.7 μM and 307.5 μM. These results demonstrate that this method provides an effective platform for identifying and screening IDO1 inhibitors from natural products.

Bioaccessibility and gut metabolism of phenolic compounds of breads added with green coffee infusion and enzymatically bioprocessed

This study aimed at investigating two strategies to enhance the bioaccessibility of phenolic compounds from whole-wheat breads: enzymatic bioprocessing and addition of green coffee infusion. Although both strategies had a significant effect on increasing the contents of total soluble phenolic compounds in breads, the addition of green coffee infusion was much more relevant (19.1-fold) than enzymatic bioprocessing (1.8-fold). The phenolic compounds present as soluble forms were completely released from all breads' matrix already at the oral phase of digestion. While gastric digestion did not promote the release of insoluble phenolic compounds, intestinal conditions led to a slight release. All bread samples showed maximum phenolic compounds bioaccessibility after 4 h of gut fermentation. Upon the end of in vitro digestion and gut fermentation, the difference between the strategies was that enzymatic bioprocessing accelerated ferulic acid release, while the addition of green coffee infusion increased 10.4-fold the overall phenolic compounds bioaccessibility.

Influence of drought stress on bioactive compounds, antioxidant enzymes and glucosinolate contents of Chinese cabbage (Brassica rapa)

This study investigated the effects of drought stress on Chinese cabbage (Chcab) by measuring plant growth responses, total antioxidant enzyme activities, the contents of bioactive compounds including glucosinolates (GLS, aliphatic and indolic), and binding with human serum albumin (HSA). Forty-day-old Chinese cabbage (Brassica rapa L. ssp. pekinensis) seedlings were transplanted into pots and maintained for three weeks at 10% (drought-treated, D-T) and 30% (control, C) soil water. The total leaf number, leaf area, and fresh and dry weights were significantly lower in D-T Chcab than in controls. Total GLSs and catalase activities were found to be significantly higher in D-T Chcab than in controls. Indolic GLSs were significantly higher than aliphatic GLSs in D-T Chcab. These results show that D-T Chcab reduced growth parameters and binding properties with HSA and influenced total contents of GLSs, polyphenols, flavonoids, total antioxidant enzyme activities, catalase and peroxidase.

Development of predictive models for total phenolics and free p-coumaric acid contents in barley grain by near-infrared spectroscopy

Barley grains are rich in phenolic compounds, which are associated with reduced risk of chronic diseases. Development of barley cultivars with high phenolic acid content has become one of the main objectives in breeding programs. A rapid and accurate method for measuring phenolic compounds would be helpful for crop breeding. We developed predictive models for both total phenolics (TPC) and p-coumaric acid (PA), based on near-infrared spectroscopy (NIRS) analysis. Regressions of partial least squares (PLS) and least squares support vector machine (LS-SVM) were compared for improving the models, and Monte Carlo-Uninformative Variable Elimination (MC-UVE) was applied to select informative wavelengths. The optimal calibration models generated high coefficients of correlation (r_pre) and ratio performance deviation (RPD) for TPC and PA. These results indicated the models are suitable for rapid determination of phenolic compounds in barley grains.