Methyl jasmonate induces oxidative/nitrosative stress and the accumulation of antioxidant metabolites in Phoenix dactylifera L.

OBJECTIVES: The present study aimed to explore the eliciting effects of increasing concentrations (50, 100, and 200 µM) of methyl jasmonate (MeJA). We cultivated actively proliferating buds of Phoenix dactylifera L. cv. Barhee in a temporary immersion system and we monitored the bioactive compound accumulation after 7 days of culture. METHODS: Total phenolic (TPC) and flavonoid (TFC) contents were determined by high-performance liquid chromatography (HPLC), Fourier-transform infrared (FTIR), and radical scavenging activity using DPPH and ABTS assays. We also explored the activity of phenylpropanoid pathway enzymes, namely phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL) and polyphenol oxidase (PPO). RESULTS: Our results revealed that MeJA treatment induced oxidative stress, and at the same time increased the activity of related defense enzymes in a dose-dependent manner. Exogenous application of MeJA at 200 µM increased ROS (two fold), hydrogen peroxide (3.7 fold), nitric oxide (14 fold), MDA (6.3 fold), superoxide dismutase (5.9 fold), catalase (4.4 fold) and guaiacol peroxidase (3.87 fold). Furthermore, the results demonstrated that 200 µM MeJA treatment enhanced the activities of PAL (3.65 fold), TAL (4.35 fold), PPO (threefold) and increased TPC (twofold) and TFC (1.75 fold) contents in buds cultures higher than the control. HPLC analysis showed that buds cultures exposed to 200 µM MeJA accumulated maximum amount of catechin (11 fold), 4-hydroxybenzoic acid (1.48 fold), caffeic acid (2.5 fold) and p-coumaric acid (1.76 fold) and demonstrate antioxidant capacity with the lowest DPPH (114.5 µg ml-1) and ABTS (90.2 µg ml-1) IC50 values on day 7 of culture as compared to the control. The MeJA in the culture medium directly reduced cell viability in a dose dependent manner up to 35% with the highest concentration. CONCLUSION: The results of this study has revealed, for the first time, that MeJA offers a promising potential for the production of phenolic compound in Phoenix dactylifera L. buds.

Effect of succinylation on the secondary structures, surface, and thermal properties of date palm pollen protein concentrate.

The present study was attempted to investigate the effect of succinylation, as chemical modification, on the functionality of male date palm pollen protein concentrate (MDPPPC). Succinylation was applied at two levels, 4 and 8 mol of succinic acid per mole of lysine. 4 M and 8 M were compared to the native MDPPPC. Findings proved that succinylation improved the surface properties of pollen protein including solubility and surfactant activity. Increased solubility of succinylated MDPPPC has been noticed especially in pH superior to pHi. The results from the differential scanning calorimetry showed a significant decrease (P < 0.05) of the denaturation temperature and the heat enthalpy for succinylated MDPPPC. ß turn of succinylated MDPPPC increased significantly (P < 0.05) at the expense of ß sheet indicating that the protein gained more mobility after succinylation which explains the enhancement of the functional properties and promotes the use of succinylated protein as a techno-functional ingredient.

Reformulation of Tunisian Sun-Dried Merguez with Camel Meat: Characterization of Physicochemical and Compositional Changes in Organic Acids, Fatty Acids, Volatile Compounds, and Minerals.

Traditional sun-dried merguez is an authentic Tunisian dried sausage made with a large number of spices and herbs, which was reformulated in this study with camel meat and hump fat and dried as in the artisanal process. This research studied the physicochemical, microbiological, and chemical compositional changes that occurred in fresh camel merguez (FCM) after 12 days of drying to achieve traditional dried camel merguez (DCM). The results showed significant weight loss (54.1%), as well as significant decreases in pH (5.20-4.97), moisture (60.5-12.3%), and water activity (0.986-0.673). These results and the acceptable microbiological quality of DCM can explain the safety of traditionally practiced long-term storage at room temperature. All chemical compositions increased upon drying. The composition of DCM included several organic acids, mainly lactate (2820 mg.kg-1); diverse unsaturated fatty acids, in particular oleic acid (33.2%); and various minerals, specifically iron (8 mg per 100 g), in addition to volatile compounds impacted by herbs and spices rich in terpenes (56.3%). These results can be useful for investing in indigenous products and promoting the exploitation of camel meat.

Moringa, Milk Thistle, and Jujube Seed Cold-Pressed Oils: Characteristic Profiles, Thermal Properties, and Oxidative Stability.

Cold-pressed moringa, milk thistle, and jujube seed oils were investigated in terms of their characteristic profiles, thermal properties, and oxidative stability. The findings proved that the extracted oils were characterized by high nutritional values, which encourages their use in various fields. Results showed significant differences between the obtained oils. Overall, jujube seed oil exhibited the best quality parameters, with acidity equal to 0.762 versus 1% for the moringa and milk thistle seed oils. Milk thistle seed oil showed absorbance in the UV-C (100-290 nm), UV-B (290-320 nm), and UV-A (320-400 nm) ranges, while the moringa and jujube seed oils showed absorbance only in the UV-B and UV-A ranges. Concerning bioactive compounds, jujube seed oil presented the highest content of polyphenols, which promoted a good scavenging capacity (90% at 10 µg/mL) compared to the moringa and milk thistle seed oils. Assessing the thermal properties of the obtained oils showed the presence of four groups of triglycerides in the moringa and milk thistle seed oils, and two groups of triglycerides in the jujube seed oil. The thermograms were constant at temperatures above 10 °C for milk thistle seed oil, 15 °C for jujube seed oil, and 30 °C for moringa seed oil, which corresponded to complete liquefaction of the oils. The extinction coefficients K232 and K270, monitored during storage for 60 days at 60 °C, proved that jujube seed oil had the highest polyphenols content and was the most stable against thermal oxidation.

Techno-functional characterization of gelatin extracted from the smooth-hound shark skins: Impact of pretreatments and drying methods.

Gelatin derived from marine by-products could be an interesting alternative to classic mammalian gelatin. The pretreatment and extraction conditions could influence the size of the resulting peptide chains and therefore their techno-functional properties. Thus, it is important to optimize the production process to get a gelatin for the appropriate applications. Skin pretreatment was done by microwaves or oven-drying and the extracted gelatin was dried by spray- or freeze-drying. Freeze-dried gelatin extracted from untreated skin (FGUS) had the highest gelatin yield (10.40%). Gelatin proximate composition showed that proteins were the major component (87.12-89.95%), while lipids showed the lowest contents (0.65-2.26%). Glycine showed the highest level (299-316/1000 residues) in the extracted gelatins. Proline and hydroxyproline residues of gelatins from untreated skin were significantly higher than those from pretreated skin-gelatin. FTIR spectra were characterized by peaks of the amide A (3430-3284 cm-1), B (3000-2931 cm-1), I (1636-1672 cm-1), II (1539-1586 cm-1) and III (1000-1107 cm-1). Spray-drying decreased the gelling properties of gelatins, since it reduced gelling and melting temperatures compared to freeze-drying. Skin pretreatment significantly reduced the gel strength of gelatin by about 50-100 g depending on the gelatin drying method. The FGUS showed better surface properties compared to other gelatins. The highest emulsion activity index (39.42 ± 1.02 m2/g) and foaming expansion (172.33 ± 2.35%) were measured at 3% FGUS. Therefore, the promising properties of freeze-dried gelatin derived from untreated skin, gave it the opportunity to be successfully used as a techno-functional ingredient in many formulations.

Optimization of a novel, gluten-free bread's formulation based on chickpea, carob and rice flours using response surface design.

This study aimed to develop nutritious, gluten-free bread with high quality characteristics using a mixture of chickpea, carob and rice flours as substitutes of wheat flour. To optimize the bread formulation, a Box-Behnken experimental design was conducted to evaluate the effect of the corresponding flour blend addition, proofing time and water amount addition on the physicochemical, technological and sensory properties of the obtained formulated bread. The optimized formulation was calculated to contain 70% of mixture flour and 100% of water, with a proofing time of 40 minutes. This formulation produced bread with greater specific volume ( 3.73 ± 0.37 cm3/g) and less baking loss ( 22.98 ± 0.94 % ) than those of control (+) bread ( 2.93 ± 0.21 cm3/g and 31.65 ± 0.72 % , respectively). Findings proved that the mixture flour based on chickpeas, carob and rice represents a good alternative to make gluten-free bread with acceptable baking properties.

Effect of extraction methods on the physicochemical, structural, functional, and antioxidant properties of the dietary fiber concentrates from male date palm flowers.

The current study evaluates the effect of both aqueous and alkaline extraction methods on the physicochemical, structural, functional, and antioxidant properties of dietary fibers (DF) from male date palm flowers (MDPF). The DF extracted by the alkali treatment (ADF) display a higher DF content as well as lower protein and lipid content than the DF resulting from watery extraction (WDF). The scanning electron microscopy, the Fourier-transform infrared spectroscopy, and the X-ray diffraction show that the alkaline treatment contributes to a slight modification of the structural characteristics of ADF leading to better purity and functional properties. The oil holding capacity and the antioxidant activity of ADF have improved compared to the WDF, which makes this concentrate a promoting functional ingredient and a natural antioxidant. Therefore, these findings confirm the wealth of both concentrates in DF, especially ADF, as well as their potential of functional and antioxidant properties, which emphasize their suitability to be used in food applications as functional ingredients. PRACTICAL APPLICATIONS: Nowadays, studies on the extraction of DF from vegetable waste are of considerable interest in the face of the rising global demand for dietetic food. The male date palm flowers (MDPF), an agricultural waste generated during the period of pollination, are valuable natural sources of DF and antioxidants. The insoluble DF of MDPF could be essential in a balanced diet as they could fight against obesity by creating a feeling of satiety. The presence of antioxidants, which are known for preventing or slowing cell damage caused by free radicals, could contribute to the improvement of the antioxidant properties of the formulated food. The functional properties of DF concentrates from MDPF are able to solve the technical problems of agri-food industries when used as food ingredients. The use of DF from MDPF, consequently, contributes to the minimization of waste and provides value addition to the by-product considered as waste in agricultural processing.