Effect of fermentation and subsequent pasteurization processes on amino acids composition of orange juice

Acute and Rapid Response of Melissa officinalis and Mentha spicata to Saline Reclaimed Water in Terms of Water Relations, Hormones, Amino Acids and Plant Oxylipins

The use of reclaimed water is considered an efficient tool for agricultural irrigation; however, the high salinity associated to this water could compromise plant quality and yields. Balm and spearmint plants were submitted for 15 days to three irrigation treatments in a controlled chamber: control with EC: 1.2 dS m^-1 (control), reclaimed water from secondary effluent (EC: 1.6 dS m^-1) (S) and water from secondary effluent with brine (EC: 4.4 dS m^-1) (SB). The plant water status, stomatal and hormonal regulation, nutritional response, concentration of amino acids and plant oxidative stress-based markers, as well as growth were evaluated. Both species irrigated with saline reclaimed water reduced leaf water potential and gas exchange in comparison with control plants, following 2 days of exposure to irrigation treatments. Nevertheless, spearmint plants recovered photosynthetic activity from the seventh day onwards, maintaining growth. This was attributed to hormonal changes and a greater accumulation of some amino acids and some plant oxylipins (phytoprostanes) in comparison to balm plants, which contributed to the improvement in the organoleptic and health-promoting properties of spearmint. A longer irrigation period with saline reclaimed water would be necessary to assess whether the quality of both species, especially spearmint, could further improve without compromising their growth.

The role of plant labile carbohydrates and nitrogen on wheat-aphid relations

Interactions between plants and herbivores are key drivers of evolution and ecosystem complexity. We investigated the role of plant labile carbohydrates and nitrogen on wheat-aphid relations in a 2² factorial combining [CO₂] and nitrogen supply. We measured life history traits (assay 1) and feeding behaviour (assay 2) of bird-cherry oat aphid (Rhopalosiphum padi L.) and English grain aphid (Sitobion avenae F.) forced to feed on single leaf laminae, and reproduction of R. padi in a setting where insects moved freely along the plant (assay 3). Experimental setting impacted aphid traits. Where aphids were constrained to single leaf, high nitrogen reduced their fitness and discouraged phloem feeding. Where aphids could move throughout the plant, high nitrogen enhanced their reproduction. Aphid responses to the interaction between nitrogen and [CO₂] varied with experimental setting. The number of R. padi adults varied tenfold with plant growing conditions and correlated negatively with molar concentration of sugars in stem (assay 3). This finding has two implications. First, the common interpretation that high nitrogen favours insect fitness because protein-rich animal bodies have to build from nitrogen-poor plant food needs expanding to account for the conspicuous association between low nitrogen and high concentration of labile carbohydrates in plant, which can cause osmotic stress in aphids. Second, the function of labile carbohydrates buffering grain growth needs expanding to account for the osmotic role of carbohydrates in plant resistance to aphids.

Chemometric analysis of amino acid profiles for detection of fruit juice adulterations - Application to verify authenticity of blood orange juice

In this work, fruit juices have been analyzed by high-performance liquid chromatography (HPLC) to measure whole amino acid profiles for various fruit types. The fruit juice authentication capabilities of whole amino acid profiles employed in various multivariate analysis methods including principal component analysis (PCA) and partial least squares (PLS) analysis have been investigated. PCA of the profiles exhibited a good separation of most fruit types and were validated using quality control samples. Furthermore, these profiles were considered in a blood orange juice versus blond orange juice adulteration study. Applying PLS regression allowed for the detection of ~20 percent blond orange juice adulterant added in blood orange juice. The highest regression coefficients were found for glutamic acid and valine, with regards to blood orange juice, and for phenylalanine and glycine, with regards to orange juice. These results suggest that chemometric approaches have great potential for the implementation in food testing.

Evaluation of the Probiotic Properties and the Capacity to Form Biofilms of Various Lactobacillus Strains

Over the last 20 years, Lactobacillus species inhabiting the gastrointestinal tract (GIT) have received much attention, and their health-promoting properties are now well-described. Probiotic effects cannot be generalized, and their uses cover a wide range of applications. It is thus important to proceed to an accurate selection and evaluation of probiotic candidates. We evaluate the probiotic potential of six strains of Lactobacillus in different in vitro models representing critical factors of either survival, efficacy, or both. We characterized the strains for their ability to (i) modulate intestinal permeability using transepithelial electrical resistance (TEER), (ii) form biofilms and resist stressful conditions, and (iii) produce beneficial host and/or bacteria metabolites. Our data reveal the specificity of Lactobacillus strains to modulate intestinal permeability depending on the cell type. The six isolates were able to form spatially organized biofilms, and we provide evidence that the biofilm form is beneficial in a strongly acidic environment. Finally, we demonstrated the ability of the strains to produce γ-aminobutyric acid (GABA) that is involved in the gut-brain axis and beneficial enzymes that promote the bacterial tolerance to bile salts. Overall, our study highlights the specific properties of Lactobacillus strains and their possible applications as biofilms.

Diffuse light affects the contents of vitamin C, phenolic compounds and free amino acids in lettuce plants

Enhancement of the diffuse solar radiation to which lettuce plants were exposed clearly affected the vitamin C content and the quantitative and qualitative patterns of phenolic compounds and free amino acids (AA) in the leaves. Although the enhanced level of diffuse light was detrimental to the contents of vitamin C and total phenolic compounds, lowering them by 10-46% and 8-11%, respectively, the content of di-caffeoyltartaric acid increased from 0.26 ± 0.19 to 0.52 ± 0.10 μmol 100 g-1 f.w. for plants harvested in summer. The effect of diffuse light on AA depended on the total amount of global radiation incident on the plants. Considering the lowest amount of global radiation, the enhanced diffuse light increased the AA content from 766 ± 89 to 849 ± 90 μmol 100 g-1 f.w. By contrast, under the highest level of global radiation, diffuse light decreased the amount of AA from 990 ± 16 to 830 ± 76 μmol 100 g-1 f.w.

Phenolic profile, free amino acids composition and antioxidant potential of dried longan fermented by lactic acid bacteria

In this study, dried longan pulp (DLP) was subjected to fermentation using selected strains of lactic acid bacteria (Lactobacillus plantarum subsp. Plantarum and Leuconostoc mesenteroides). We then studied changes in the free and bound phytochemical profile, antioxidant activity, free amino acid, and organic acid composition. Fermentation exhibited a 17.4% and 5.7% increase in the amount of free and total phenolic contents of DLP. Phenolic composition determined by HPLC revealed significant changes due to fermentation that were primarily in the contents of gallic acid, vanillic acid, 4-methylcatechol and p-coumaric acid, resulting in a 37.9% and 25.7% increase in free gallic acid and 4-methylcatechol, respectively. Fermentation was also found to enhance the ferric reducing antioxidant power of both free and total and the oxygen radical absorbance capacity of free phenolic fraction by 18.3%, 11.8%, and 37.4%, respectively. In addition, fermentation was observed to reduce the contents of free amino acids with bitter taste (phenylalanine, tyrosine and leucine), and increase amino acids (taurine, aspartic acid, cysteine, cysteine thiazoline and γ-amino-butyric acid) having antioxidant potential. Therefore, this study provides basis for the production of fermented longan-based functional products with improved antioxidant activity.

Preservation of Bioactive Compounds and Quality Parameters of Watermelon Juice Enriched with L-Citrulline through Short Thermal Treatment

L-citrulline is a nonessential amino acid with demonstrated health benefits for humans, and watermelon is a fruit rich in this amino acid. The juice industry is developing functional beverages through the enrichment with external bioactive compounds; this kind of industry uses conventional pasteurization because of its efficiency and simplicity. In this experiment, the effects of pasteurization (80°C for 40 s or 90 s) and storage (4°C for 30 days) on different parameters were evaluated in a watermelon juice (3.68 g kg−1of natural L-citrulline) enriched with external L-citrulline (12 g kg−1). Enzymatic activity (peroxidase, pectin methyl esterase, and polygalacturonase) was inactivated (74 to 89%, 89 to 90%, and 11 to 15%, resp.) with the pasteurization treatment, obtaining the highest degradation with the longest heating time. According to the rheology study, the juice’s elasticity was mainly affected by type of heat treatment while its viscosity was more stable and affected by storage time. A reduction in bioactive compounds content, around 10–16% for lycopene and 19–20% for L-citrulline, was observed after the pasteurization treatments, with a higher decrease with increased treatment time. Storage time also induced a reduction in lycopene and L-citrulline. The shelf life was limited by sensorial parameters.

Quantitation of Thioprolines in Grape Wine by Isotope Dilution-Liquid Chromatography-Tandem Mass Spectrometry

Cysteine reacts with reactive carbonyls to form thioprolines, which have been demonstrated to possess various pharmaceutical properties. Therefore, thioproline formation is considered as a major detoxification pathway for carcinogenic reactive carbonyls. In this study, we report the initial identification of thiazolidine-4-carboxylic acid (1) and 2-methylthiazolidine-4-carboxylic acid (2), two very common thioprolines, formed by reacting formaldehyde and acetaldehyde with cysteine in grape wine samples. We have developed an isotope dilution-liquid chromatography-tandem mass spectrometry method featuring high sensitivity (limit of detection of ≤1.5 ng/mL) and selectivity to quantitate compounds 1 and 2. The method after validated to be highly accurate (recovery of ≥92%) and precise [intraday relative standard deviation (RSD) of ≤4.1% and interday RSD of ≤9.7%] was applied to determine the varying compound 1 and 2 contents in grape wine samples. Results revealed the grape type and storage duration-dependent formation of thioprolines in grape wines. Overall, the results are expected to facilitate compound-dependent investigations of the health benefits of grape wine, and our findings could be adopted to predict the age of grape wine.