Effects of Arbuscular Mycorrhization on Fruit Quality in Industrialized Tomato Production

Industrialized tomato production faces a decrease in flavors and nutritional value due to conventional breeding. Moreover, tomato production heavily relies on nitrogen and phosphate fertilization. Phosphate uptake and improvement of fruit quality by arbuscular mycorrhizal (AM) fungi are well-studied. We addressed the question of whether commercially used tomato cultivars grown in a hydroponic system can be mycorrhizal, leading to improved fruit quality. Tomato plants inoculated with Rhizophagus irregularis were grown under different phosphate concentrations and in substrates used in industrial tomato production. Changes in fruit gene expression and metabolite levels were checked by RNAseq and metabolite determination, respectively. The tests revealed that reduction of phosphate to 80% and use of mixed substrate allow AM establishment without affecting yield. By comparing green fruits from non-mycorrhizal and mycorrhizal plants, differentially expressed genes (DEGs) were found to possibly be involved in processes regulating fruit maturation and nutrition. Red fruits from mycorrhizal plants showed a trend of higher BRIX values and increased levels of carotenoids in comparison to those from non-mycorrhizal plants. Free amino acids exhibited up to four times higher levels in red fruits due to AM, showing the potential of mycorrhization to increase the nutritional value of tomatoes in industrialized production.

Physiological Approach to the Use of the Natural Compound Quinate in the Control of Sensitive and Resistant Papaver rhoeas

Quinate (1,3,4,5-tetrahydroxycyclohexanecarboxylate) is a compound synthesized in plants through a side-branch of the shikimate biosynthesis pathway, which is accumulated after glyphosate and acetolactate synthase inhibiting herbicides (ALS-inhibitors) and has phytotoxic potential. The objective of this study was to evaluate the phytotoxicity of quinate on several weed species. Among the species evaluated, Cynodon dactylon, Bromus diandrus, Lolium rigidum, Sinapis alba, and Papaver rhoeas, P. rhoeas was the most sensitive, and its growth was controlled with quinate concentrations above 100 mM at the phenological stage of 6–8 true leaves. A physiological study, including the shikimate pathway and the physiological markers of ALS-inhibitors (carbohydrates and amino acids), was performed in the sensitive and resistant plants treated with sulfonylureas or quinate. The typical physiological effects of ALS-inhibitors were detected in the sensitive population (free amino acid and carbohydrate accumulation) and not detected in the resistant population. The mode of action of quinate appeared to be related to general perturbations in their carbon/nitrogen metabolism rather than to specific changes in the shikimate pathway. These results suggest the possibility of using quinate in the weed control management of P. rhoeas.

Free Amino Acids in Three Pleurotus Species Cultivated on Agricultural and Agro-Industrial By-Products

Previous studies have demonstrated the feasibility of employing by-products of the olive and wine sectors for the production of Pleurotus mushrooms with enhanced functionalities. In this work we investigated the influence of endogenous and exogenous factors on free amino acids (FAAs) profile of Pleurotus ostreatus, P. eryngii and P. nebrodensis mushrooms produced on wheat straw (WS), alone or mixed with grape marc (GM), and on by-products of the olive industry (OL). Overall, 22 FAAs were determined in substrates and mushrooms, including all the essential amino acids, the neurotransmitter γ-aminobutyric acid (GABA) and ornithine. On a dry weight (dw) basis, total FAAs ranged from 17.37 mg/g in P. nebrodensis to 130.12 mg/g in P. ostreatus samples, with alanine, leucine, glutamine, valine and serine predominating. Similar distribution patterns were followed by the monosodium glutamate (MSG)-like, sweet and bitter FAAs. Significant differences in FAAs level were observed among the species examined and among the cultivation substrates used. Principal Component Analysis (PCA) performed on the entire FAAs profile of six Pleurotus strains, clearly separated P. ostreatus from P. eryngii and P. nebrodensis, in accordance to their phylogenetic affinity. This is the first report of FAAs in P. nebrodensis.

Analytical strategy coupled to chemometrics to differentiate Camellia sinensis tea types based on phenolic composition, alkaloids, and amino acids

Catechins, amino acids, and alkaloids are primary chemical components of tea and play a crucial role in determining tea quality. Their composition and content largely vary among different types of tea. In this study, a convenient chemical classification method was developed for six Camellia sinensis tea types (white, green, oolong, black, dark, and yellow) based on the quantification of their major components. Twenty-one free amino acids, 6 catechins, 2 alkaloids, and gallic acid in 24 teas were quantified using ultra-high-performance liquid chromatography (UHPLC). The total catechin contents in these tea samples ranged from 10.96 to 95.67 mg/g, while total free amino acid content ranged from 2.63 to 25.89 mg/g. Theanine (Thea) was the most abundant amino acid in all tea varieties. Catechin and amino acid levels in tea were markedly reduced upon fermentation of tea. Furthermore, high-temperature processing (roasting) during tea production induced degradation and epimerization of catechins, yielding epimerized catechins, simple catechins, and gallic acid. Principal component analysis revealed that major ester-catechins (EGCG and ECG), major amino acids (Thea), and major alkaloids (caffeine) are potential factors for distinguishing different types of tea. Linear discriminant analysis showed that 100% of teas were correctly classified in which (+)-catechin, ECG, EGC, gallic acid, GABA, cysteine, lysine, and threonine were the most discriminating compounds. This study shows that quantification of the major tea components combined with chemometric analysis, can serve as a simple, convenient, and reliable approach for classifying tea according to fermentation level. PRACTICAL APPLICATION: Different Camellia sinensis tea types can be produced worldwide but it is still challenging to know which chemical markers can be used to trace their production. in this paper we used a targeted methodology to classify six tea types (white, green, oolong, black, dark, and yellow) based on phenolic composition, alkaloids, and amino acids. The main chemical markers responsible for the discrimination were pinpointed with the use of chemometric tools.

Fatty Acids and Free Amino Acids Changes during Processing of a Mediterranean Native Pig Breed Dry-Cured Ham

The aim of this work is to analyse the intramuscular fatty acids and the free amino (FAA) acids in Chato murciano dry-cured ham. There are several Mediterranean native pig breeds whose characteristics of derived products have been described, but the impact of lipolysis and proteolysis on Chato murciano dry-cured ham has not yet been studied. Fatty acids and free amino acids were determined in the fresh piece and at 14, 18, 22 and 24 months of manufacturing. Monounsaturated fatty acids are the majority in the neutral lipids and free fatty acid fractions. Lipolysis took place mainly until the 18th month, resulting in a decrease in the levels of fatty acids of neutral lipids (from 95.43% to 83.38%) and polar lipids (from 2.57% to 0.41%), accompanied by a corresponding increase in free fatty acids (from 2% to 16.21%). Neutral lipids hydrolysis provides the main free fatty acids as in other native breeds. Results for FAA showed an increase in concentration during the time preceding the 14th month. From this point onwards, until month 18, total FAA concentration remained stable, and the content decreased at the end of the processing (between months 22 and 24).

Mechanisms of Soybean Host-Plant Resistance Against Megacopta cribraria (Hemiptera: Plataspidae)

A number of soybean varieties traditionally bred for resistance to various soybean arthropod pests have been identified as resistant to Megacopta cribraria (F.) (Hemiptera: Plataspidae). However, the mechanisms of host-plant resistance (HPR) in this system are not understood. The goal of this study was to identify the mechanisms of resistance by examining the role of plant volatile organic compounds (VOCs) and free amino acids (FAAs) among 16 soybean varieties. Choice and no-choice cage experiments identified several soybean varieties that demonstrated antixenosis as well as antibiosis. However, resistance varied over time in certain soybean varieties, such as N02-7002 and PI567352B. Mean nymph number from choice experiments had positive correlations with the FAAs asparagine, tryptophan, alanine, phenylanaline, and serine; negative correlation with leucine and threonine. Four plant volatiles, hexanal, 2-pentylfuran, beta-cyclocitral, and cis-9-hexadecenal, were positively correlated with subsequent nymph development, whereas n-hexadecenoic acid was negatively correlated with nymph number only, in adult choice cage experiments. This study contributes to understanding the mechanisms of HPR through associations with plant VOCs and FAAs in relation to M. cribraria development and provides useful knowledge for developing soybean varieties for M. cribraria management.

Changes in free amino acids of fermented minced peppers during natural and inoculated fermentation process based on HPLC-MS/MS

Free amino acids (FAAs) participate in the synthesis of quality characteristic ingredients and taste substances in fermented minced peppers (FMPs), and they can be affected by fermentation method and time. In this study, changes in FAAs of FMP during natural fermentation (NF) and inoculated fermentation (IF) process were characterized by HPLC-MS/MS. The results showed that a total of 20 FAAs were identified, including 8 essential amino acids (AAs), 2 semiessential AAs, and 10 nonessential AAs. Comparing with other FAAs, Gln, Arg, and Asn presented higher content in the whole NF or IF periods. The FAAs content of NF and IF samples showed similar tendency during fermentation process, which first increased and then decreased. The highest content of most FAAs in IF and NF samples was obtained on the 18- and 12-day, respectively. Moreover, the FAA content in IF samples was higher than that in NF ones at the same fermentation time. The taste AAs content accounted for 23.3% to 50.0% in total FAAs, and taste activity value of bitter and umami was higher than sweet and aromatic ones. Based on principal component analysis, comprehensive analysis ranking, and heat map clustering analysis, FMP obtained by IF posed better FAAs quality than NF samples during fermentation process. PRACTICAL APPLICATION: Free amino acids (FAAs) participate in the synthesis of quality characteristic ingredients and taste substances in fermented minced peppers (FMPs), and they can be affected by fermentation method and time. Changes in FAA varieties and level in FMP during natural fermentation (NF) and inoculated fermentation (IF) process were analyzed using HPLC-MS/MS. Then, they were performed by principal component analysis (PCA), and clustered with the heat map. The results showed that FMP obtained by IF posed better FAAs quality than NF samples in the whole fermentation. HPLC-MS/MS was a reliable and effective mean for determining the FAAs and could provide regulation guidelines for improving the quality of FMP during fermentation process.

Determination of free amino acids, organic acids, and nucleotides in 29 elegant spices

Spices can be used in cooking to enhance the flavor of food. In order to systematically summarize and discuss the flavor components of 29 elegant spices, the free amino acids, nucleotides, and organic acids in these spices were detected by high-performance liquid chromatography. Cluster analysis was carried out to classify the 29 elegant spices based on similar data. The results showed considerable variations in the total free amino acids (1.12‒31.59 g/kg), organic acids (9.63‒71.90 g/kg), and nucleotides (0.03‒2.72 g/kg) in the elegant spices. Nine of the amino acids, especially glutamic acid and arginine, were found to have a taste active value (TAV) greater than 1. The TAVs of the 5'-nucleotides, succinic acid, oxalic acid, tartaric acid, and ascorbic acid were all >1. The equivalent umami concentration (EUC) of sweet marjoram was 83.69 g MSG/100 g. The 29 elegant spices were divided into two categories according to cluster analysis of the EUC. Oregano fell into one category, and the remaining 28 spices fell into the other category.

Ecometabolomics for a Better Understanding of Plant Responses and Acclimation to Abiotic Factors Linked to Global Change

The number of ecometabolomic studies, which use metabolomic analyses to disentangle organisms' metabolic responses and acclimation to a changing environment, has grown exponentially in recent years. Here, we review the results and conclusions of ecometabolomic studies on the impacts of four main drivers of global change (increasing frequencies of drought episodes, heat stress, increasing atmospheric carbon dioxide (CO2) concentrations and increasing nitrogen (N) loads) on plant metabolism. Ecometabolomic studies of drought effects confirmed findings of previous target studies, in which most changes in metabolism are characterized by increased concentrations of soluble sugars and carbohydrate derivatives and frequently also by elevated concentrations of free amino acids. Secondary metabolites, especially flavonoids and terpenes, also commonly exhibited increased concentrations when drought intensified. Under heat and increasing N loads, soluble amino acids derived from glutamate and glutamine were the most responsive metabolites. Foliar metabolic responses to elevated atmospheric CO2 concentrations were dominated by greater production of monosaccharides and associated synthesis of secondary metabolites, such as terpenes, rather than secondary metabolites synthesized along longer sugar pathways involving N-rich precursor molecules, such as those formed from cyclic amino acids and along the shikimate pathway. We suggest that breeding for crop genotypes tolerant to drought and heat stress should be based on their capacity to increase the concentrations of C-rich compounds more than the concentrations of smaller N-rich molecules, such as amino acids. This could facilitate rapid and efficient stress response by reducing protein catabolism without compromising enzymatic capacity or increasing the requirement for re-transcription and de novo biosynthesis of proteins.

The Impact of High-Pressure Processing on Physicochemical Properties and Sensory Characteristics of Three Different Lamb Meat Cuts

This study investigated the effects of high pressure processing (HPP) on the physicochemical properties and sensory characteristics of different lamb meat cuts. Lamb meat discolouration occurred when HPP was applied at 400 and 600 MPa. Thiobarbituric acid reactive substances (TBARS) values significantly increased with pressure increase from 200 to 600 MPa for loin cut, and 300 to 600 MPa for shoulder and shank cuts. Saturated fatty acid and polyunsaturated fatty acid content significantly decreased with pressure increase from 200 to 600 MPa for shank and shoulder cuts, and 300 to 600 MPa for loin cut. Free amino acids content significantly increased in shank and loin cuts with pressure increase after 200 MPa, and in shoulder cuts after 400 MPa. In addition, samples treated with HPP at high pressure levels of 400 and 600 MPa were associated with browned, livery and oxidized flavours. The pressure levels applied and type of cuts used are important considerations during HPP processing as they influenced physicochemical and sensory properties of lamb samples.

Research on the quality changes of grass carp during brine salting

The research on the quality changes of grass carp during brine salting with 6%, 8%, and 10% salt additions was evaluated by chemical and physical indicators, as well as a sensory assessment and microbiological analysis. The NaCl content was proportional to salt addition and salting time. The increase of salt addition could lead to the increase of hardness and chewiness in which change trends were contrary to the pH within 24 hr. All K values were less than 10% during brine salting. The effect of 8% salt additions on free amino acids was relatively smaller. Higher levels of salt additions could inhibit bacterial growth. Combined with sensory assessment, equivalent umami concentration (EUC), and taste activity value (TAV) to analysis comprehensively, it was suggested that grass carp meat should be eaten at 4-8 hr of brine salting with 8% salt additions or processed for the next step, in which the grass carp meat had a better taste and quality.

Free Amino Acids in Human Milk: A Potential Role for Glutamine and Glutamate in the Protection Against Neonatal Allergies and Infections

Breastfeeding is indicated to support neonatal immune development and to protect against neonatal infections and allergies. Human milk composition is widely studied in relation to these unique abilities, which has led to the identification of various immunomodulating components in human milk, including various bioactive proteins. In addition to proteins, human milk contains free amino acids (FAAs), which have not been well-studied. Of those, the FAAs glutamate and glutamine are by far the most abundant. Levels of these FAAs in human milk sharply increase during the first months of lactation, in contrast to most other FAAs. These unique dynamics are globally consistent, suggesting that their levels in human milk are tightly regulated throughout lactation and, consequently, that they might have specific roles in the developing neonate. Interestingly, free glutamine and glutamate are reported to exhibit immunomodulating capacities, indicating that these FAAs could contribute to neonatal immune development and to the unique protective effects of breastfeeding. This review describes the current understanding of the FAA composition in human milk. Moreover, it provides an overview of the effects of free glutamine and glutamate on immune parameters relevant for allergic sensitization and infections in early life. The data reviewed provide rationale to study the role of free glutamine and glutamate in human milk in the protection against neonatal allergies and infections.

[Gender differences in the pool of free amino acid neurotransmitters in Krushinsky-Molodkina rats]

The study of the role of neurotransmitter systems in the pathogenesis of epilepsy is one of the priorities of epileptology. New data on the functions of free neurotransmitter-like amino acid in the central nervous system are of the greatest importance and determine the prospects for the development of novel effective anticonvulsants. It is widely believed in clinical medicine that epilepsy has distinct gender characteristics. The aim of this study was to investigate the gender peculiarities in the content of neurotransmitter amino acids in the brain of Krushinsky-Molodkina (KM) rats, which were used as model organisms for the study of genetically induced audiogenic epilepsy. The content of Asp, Glu, GABA, Gly, and Tau of the medulla oblongata, hippocampus and cerebral cortex were determined using high-performance liquid chromatography (HPLC) in intact KM rats, KM rats exposed to a series of epileptiform seizures, and Wistar rats (control group). Both the Wistar and KM rats had gender distinctions in the distribution of free amino acids among the investigated brain parts. The audiogenic epilepsy was characterized by smoothing gender differences as well as differences between the concentrations of free amino acids in the cortex and medulla oblongata, specific for Wistar rats. The changes observed in male rats after the set of seizures included the increase in GABA concentration and a decrease in the Gly level in all investigated brain parts, as well as the decrease of the Tau content in the cortex and hippocampus. At the same time, the Glu content in cortex increased, while the Asp level decreased. After 6 days of audiogenic stimulations the female KM rats demonstrated the increase in the Glu level in all investigated brain parts, the increase in Gly and Asp levels in hippocampus, and no changes in the GABA content. Thus, after the set of epileptiform seizures the KM rats achieved a new steady state of the studied amino acids pool, which differed in males and females. In this case, gender differences significantly changed after the seizures.

Impact of Nisin-Producing Strains of Lactococcus lactis on the Contents of Bioactive Dipeptides, Free Amino Acids, and Biogenic Amines in Dutch-Type Cheese Models

The goal of this study was to determine changes in contents of free amino acids, biogenic amines, and bioactive dipeptides (anserine and L-carnosine) in cheese models produced with the addition of nisin-producing strains of Lactococcus lactis over their ripening period. After 5 weeks of ripening, contents of total biogenic amines in the cheese models with the addition of L. lactis strains were lower than in the control cheese model. The cheese models examined differed significantly in contents of free amino acids through the ripening period. Individual free amino acids, such as ornithine, were found in some of the cheese models, which is indicative of their specific microbial activities. Both anserine and L-carnosine were detected in all variants of the cheese models. After 5-week ripening, the highest total content of bioactive dipeptides was determined in the cheese models produced with the nisin-producing culture of L. lactis 11454 (142.15 mg∙kg⁻¹).

Novel processing techniques and spinach juice: Quality and safety improvements

In this study, the combined effect of ultrasound (US) and pulsed electric field (PEF) techniques was analyzed for the quality improvement and microbial safety of spinach juice. The spinach juice was treated with US at frequency of 40 kHz, radiating power of 200 W below 30 ± 2 °C temperature for 21 min in ultrasonic bath cleaner, and PEF treatment (pulse frequency: 1 kHz, flow rate: 60 mL/min, temperature: 30 ± 2 °C, time: 335 µs, electric field strength 9 kV/cm) was done. In results, the combined (US-PEF) treatment attained the highest value of minerals and total free amino acids as compared to US or PEF treatment alone. US-PEF treatment significantly reduced the total plate count (3.83 to 1.97 log CFU/mL), E. coli/Coliform (1.90 to 0.75 log CFU/mL) and yeast and mold (4.23 to 2.22 log CFU/mL). Fourier-transform infrared spectroscopy (FT-IR) spectra showed that all nonthermal treatments led to a higher concentration of carbonyl compounds rather generate new carbonyl compounds. US-PEF treatment significantly reduced the particle size. The rheology of spinach juice was drastically changed by all nonthermal techniques, indicating non-Newtonian modal accompanied by a decrease of consistency index (K), apparent viscosity (η), and increase of flow behavior (n). Overall, the improved quality of spinach juice shows the suitability of both technologies for industrial applications despite the variations in rheological properties. PRACTICAL APPLICATION: Nowadays, nonthermal technologies like US and PEF are being used to enhance the nutritional quality and stability of different fruits and vegetable juices. The current research shows that US-PEF application can enhance the free amino acids and mineral contents while significantly decrease microbial activities and particle size. The rheology of spinach juice can be dramatically changed, through the reduction of consistency index (K), apparent viscosity (η) and elevation of flow behavior (n). The results of this research proposed that US-PEF treatment can be a more suitable nonthermal application to enhance the quality of spinach juice at an industrial scale.

Impact of Extending Hard-Cheese Ripening: A Multiparameter Characterization of Parmigiano Reggiano Cheese Ripened up to 50 Months

Extending ripening of hard cheeses well beyond the traditional ripening period is becoming increasingly popular, although little is known about the actual evolution of their characteristics. The present work aimed at investigating selected traits of Parmigiano Reggiano cheese ripened for 12, 18, 24, 30, 40 and 50 months. Two cheeses per each ripening period were sampled. Although moisture constantly decreased and was close to 25% in 50-month cheeses, with a parallel increase in cheese hardness, several biochemical changes occurred involving the activity of both native and microbial enzymes. Capillary electrophoresis demonstrated degradation of α_s1- and β-casein, indicating residual activity of both chymosin and plasmin. Similarly, continuous release of free amino acids supported the activity of peptidases deriving from lysed bacterial cells. Volatile flavor compounds, such as short-chain fatty acids and some derived ketones, alcohols and esters, evaluated by gas chromatography with solid-phase micro-extraction, accumulated as well. Cheese microstructure was characterized by free fat trapped in irregularly shaped areas within a protein network, with native fat globules being no longer visible. This study showed for the first time that numerous biochemical and structural variations still occur in a hard cheese at up to 50 months of aging, proving that the ripening extension deserves to be highlighted to the consumer and may justify a premium price.

A free amino acid-based diet partially prevents symptoms of cow's milk allergy in mice after oral sensitization with whey

BACKGROUND

Amino acid-based formulas (AAFs) are used for the dietary management of cow's milk allergy (CMA). Whether AAFs have the potential to prevent the development and/or symptoms of CMA is not known.

OBJECTIVE

The present study evaluated the preventive effects of an amino acid (AA)-based diet on allergic sensitization and symptoms of CMA in mice and aimed to provide insight into the underlying mechanism.

METHODS

C3H/HeOuJ mice were sensitized with whey protein or with phosphate-buffered saline as sham-sensitized control. Starting 2 weeks before sensitization, mice were fed with either a protein-based diet or an AA-based diet with an AA composition based on that of the AAF Neocate, a commercially available AAF prescribed for the dietary management of CMA. Upon challenge, allergic symptoms, mast cell degranulation, whey-specific immunoglobulin levels, and FoxP3+ cell counts in jejunum sections were assessed.

RESULTS

Compared to mice fed with the protein-based diet, AA-fed mice had significantly lower acute allergic skin responses. Moreover, the AA-based diet prevented the whey-induced symptoms of anaphylaxis and drop in body temperature. Whereas the AA-based diet had no effect on the levels of serum IgE and mucosal mast cell protease-1 (mMCP-1), AA-fed mice had significantly lower serum IgG2a levels and tended to have lower IgG1 levels (P = .076). In addition, the AA-based diet prevented the whey-induced decrease in FoxP3+ cells. In sham-sensitized mice, no differences between the two diets were observed in any of the tested parameters.

CONCLUSION

This study demonstrates that an AA-based diet can at least partially prevent allergic symptoms of CMA in mice. Differences in FoxP3+ cell counts and serum levels of IgG2a and IgG1 may suggest enhanced anti-inflammatory and tolerizing capacities in AA-fed mice. This, combined with the absence of effects in sham-sensitized mice indicates that AAFs for the prevention of food allergies may be an interesting concept that warrants further research.

Cysteine Protease Inhibitors Reduce Enzymatic Browning of Potato by Lowering the Accumulation of Free Amino Acids

Enzymatic browning is a major issue affecting the quality of processed potato (Solanum tuberosum L.). To understand the molecular mechanism of browning, transcriptional analyses were performed by employing potatoes that differed in browning. Coexpression analysis indicated that 9 out of 15 upregulated genes in browning-less groups encoded for potato protease inhibitors (StPIs). In addition, gene otology analysis showed that the enriched terms were mainly involved in protease inhibitors. Overexpression of cysteine StPI 143 and StPI 146 individually reduced browning and lowered protease activities and tyrosine and total free amino acid (FAA) contents, but they could not decrease polyphenol oxidase activity. Moreover, supplementing exogenous tyrosine or total FAAs into transgenic potato mash to wild-type amounts promoted mash browning, browning with total FAAs, more than with tyrosine, resembling wild-type levels. These results implied that cysteine StPIs reduced browning via lowering the accumulation of FAAs in addition to tyrosine. Our findings have enriched the knowledge about the roles and mechanisms of protease inhibitors in regulating enzymatic browning of potato, which provide new ways for controlling potato browning.

Differentiation between Ripening Stages of Iberian Dry-Cured Ham According to the Free Amino Acids Content

In this paper, the differentiation of three ripening stages, postsalting, drying, and cellar, of Iberian dry-cured ham has been carried out according to their free amino acids contents. Eighteen L-amino acids, alanine, 2-aminobutanoic acid, aspartic acid, cysteine, glutamine, glycine, histidine, hydroxyproline, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tyrosine, and valine have been determined by gas chromatography with derivatization with N,O-bis(trimethylsilyl)-trifluoroacetamide. Gas chromatography-mass spectrometry was used to confirm the presence of the eighteen amino acids in the ham samples, and gas chromatography using a DB-17HT column and flame ionization detector was used for quantitative determination. Extraction with a mixture methanol-acetonitrile has been carried out, achieving recoveries in the range 52-164%. Methimazole was used as internal standard. Limits of detection ranged between 7.0 and 611.7 mg·kg-1. Free amino acids have been used as chemical descriptors to differentiate between the ripening stages. Principal component analysis and linear discriminant analysis have been used as chemometric techniques, achieving complete differentiation between the ripening stages. Alanine, tyrosine, glutamine, proline, 2-aminobutanoic acid, cysteine, and valine were the most differentiating amino acids.

Effect of heat wave on N2 fixation and N remobilisation of lentil (Lens culinaris MEDIK) grown under free air CO2 enrichment in a mediterranean-type environment

The stimulatory effect of elevated [CO₂ ] (e[CO₂ ]) on crop production in future climates is likely to be cancelled out by predicted increases in average temperatures. This effect may become stronger through more frequent and severe heat waves, which are predicted to increase in most climate change scenarios. Whilst the growth and yield response of some legumes grown under the interactive effect of e[CO₂ ] and heat waves has been studied, little is known about how N₂ fixation and overall N metabolism is affected by this combination. To address these knowledge gaps, two lentil genotypes were grown under ambient [CO₂ ] (a[CO₂ ], ~400 µmol·mol^-1 ) and e[CO₂ ] (~550 µmol·mol^-1 ) in the Australian Grains Free Air CO₂ Enrichment facility and exposed to a simulated heat wave (3-day periods of high temperatures ~40 °C) at flat pod stage. Nodulation and concentrations of water-soluble carbohydrates (WSC), total free amino acids, N and N₂ fixation were assessed following the imposition of the heat wave until crop maturity. Elevated [CO₂ ] stimulated N₂ fixation so that total N₂ fixation in e[CO₂ ]-grown plants was always higher than in a[CO₂ ], non-stressed control plants. Heat wave triggered a significant decrease in active nodules and WSC concentrations, but e[CO₂ ] had the opposite effect. Leaf N remobilization and grain N improved under interaction of e[CO₂ ] and heat wave. These results suggested that larger WSC pools and nodulation under e[CO₂ ] can support post-heat wave recovery of N₂ fixation. Elevated [CO₂ ]-induced accelerated leaf N remobilisation might contribute to restore grain N concentration following a heat wave.

Lighting intensity and photoperiod serves tailoring nitrate assimilation indices in red and green baby leaf lettuce

BACKGROUND

Understanding plant responses to light quantity in indoor horticultural systems is important for optimising lettuce growth and metabolism as well as energy utilisation efficiency. Light intensity and photoperiod sufficient for normal plant growth parameters might be not efficient for nitrate assimilation. Therefore, this study explored and compared the effects of different light intensities (100-500 μmol m-2 s-1 ) and photoperiods (12-24 h) on the growth and nitrate assimilation in red and green leaf lettuce (Lactuca sativa L.).

RESULTS

For efficient nitrate assimilation, 300-400 μmol m-2 s-1 photosynthetic photon flux density (PPFD) and 16-18 h photoperiod is necessary for red and green lettuces. The insufficient light quantity resulted in reduced growth and remarkable increase in nitrate and nitrite contents in both cultivars. Short photoperiods, similarly to low PPFD, growth parameters, chlorophyll indices and nitrate assimilation indices showed the shortage of photosynthetic products for normal plant physiological processes. Short photoperiods had the least pronounced effect on nitrate and nitrite contents in lettuce leaves.

CONCLUSION

Light intensity was superior compared to photoperiods for efficient nitrate assimilation in both lettuce cultivars. Under short photoperiods, similarly to low intensity, growth parameters, chlorophyll index and nitrate assimilation indices showed a shortage of photosynthetic products for normal physiological processes. The free amino acid concentration increased, but it was not efficiently incorporated in proteins, as their level in lettuce was lower compared to those for moderate photoperiods. © 2019 Society of Chemical Industry.

A Comparative Characterization of Physicochemical and Antioxidants Properties of Processed Heterotrigona itama Honey from Different Origins and Classification by Chemometrics Analysis

Stingless bee honey produced by Heterotrigona itama from different botanical origins was characterised and discriminated. Three types of stingless bee honey collected from acacia, gelam, and starfruit nectars were analyzed and compared with Apis mellifera honey. The results showed that stingless bee honey samples from the three different botanical origins were significantly different in terms of their moisture content, pH, free acidity, total soluble solids, colour characteristics, sugar content, amino acid content and antioxidant properties. Stingless bee honey was significantly different from Apis mellifera honey in terms of physicochemical and antioxidant properties. The amino acid content was further used in the chemometrics analysis to evaluate the role of amino acid in discriminating honey according to botanical origin. Partial least squares-discriminant analysis (PLS-DA) revealed that the stingless bee honey was completely distinguishable from Apis mellifera honey. Notably, a clear distinction between the stingless bee honey types was also observed. The specific amino acids involved in the distinction of honey were cysteine for acacia and gelam, phenylalanine and 3-hydroxyproline for starfruit, and proline for Apis mellifera honey. The results showed that all honey samples were successfully classified based on amino acid content.

Quantitative Analyses of Key Odorants and Their Precursors Reveal Differences in the Aroma of Gluten-Free Rice Bread and Wheat Bread

Rice flour is one of the most important raw materials in gluten-free products. However, the aroma of gluten-free rice bread is less accepted by consumers than that of commercial wheat bread. Therefore, 18 selected aroma compounds were determined in rice and wheat breads by stable isotope dilution assays (SIDA) to elucidate differences in the sensory characteristics, concentrations, and odor activity values (OAVs). The OAVs of most aroma compounds varied greatly between a rice and a wheat bread. In particular, 2-aminoacetophenone with a grape-like, medicinal aroma was characteristic for rice bread crumb and crust, while maltol was only relevant in wheat bread crust. Ehrlich pathway products varied in their concentration between the bread crumbs and were correlated with the contents of their corresponding free amino acid precursors in the flours and doughs. The analysis of rice flour revealed that only a few aroma compounds were retained in the bread. Consequently, the bread making process has a high relevance in aroma compound formation. In a comparison of breads prepared from fresh and stored rice flour, hexanal was identified as an important indicator for aging in rice bread and flour.

Free Amino Acid Content in Human Milk is Associated with Infant Gender and Weight Gain during the First Four Months of Lactation

Background: There is a growing interest regarding the physiological role of free amino acids (FAA) present in human milk (HM). Recent studies show FAA in HM could be influenced by infants’ gender and could have an important role in their growth and development. We studied the concentrations of FAA in HM and potential associations with infants’ gender and their patterns of growth in a cohort of Ecuadorian women. Methods: Human milk samples were collected after approximately eight hours of overnight fast within one week (colostrum), 2 weeks (transition milk), and 2 and/or 4 months (mature milk) after parturition. Free AA were determined by cation-exchange chromatography separation. Results: We observed significantly higher concentrations of Glu 14.40 (1.35, 27.44), Gly 1.82 (0.24, 3.4), Cys 0.36 (0.03, 0.68), and Tyr 0.24 (0.02, 0.46) in HM intended for boys. Free Glu, Gly, Cys, and Tyr concentrations increased with time of lactation. In addition, there were higher concentrations of Glu 28.62 (1.78, 55.46) and Ala 7.16 (1.26, 13.06) in HM for children that presented faster weight gain than for those with slower gain. Conclusions: The present results showed that there are differences in FAA levels in HM intended for male and fast-growing children.

Anti-Microbiological, Anti-Hyperglycemic and Anti-Obesity Potency of Natural Antioxidants in Fruit Fractions of Saskatoon Berry

The aim of the present work was to evaluate for content of phytochemicals (monophosphate nucleotides, free amino acids, polyphenols), and for anti-microbiological, anti-diabetic (ability to inhibit pancreatic lipase, α-glucosidase, and α-amylase), and antioxidant activities in seven selected fruit and fruit fractions of Amelanchier alnifolia. Most of the fruit and fruit fractions analyzed in this study have not been examined in this respect until now. The content of monophosphate nucleotides and free amino acids were tested by ultra-performance liquid chromatography coupled with photodiode array detector and electrospray ionization-mass spectrometry (UPLC-PDA-ESI-MS). The distribution of the examined compounds and biological activity differed significantly depending on the tested fruit and parts of the fruit. Cultivars “Smoky” and “Thiessen” had a high content of essential free amino acids, monophosphate nucleotides, and the highest antioxidant activity. They were also accountable for the high ability to inhibit Enterococcus hirae (anti-bacterial activity), of activity toward α-amylase, α-glucosidase, and pancreatic lipase. Moreover, the fruit peel was abundant in polyphenolic compounds and showed the highest antioxidative activity, which were strongly correlated with each other. In addition, the peel was characterized by a high concentration of monophosphate nucleotides, free amino acids, and were responsible above all for the strong ability to inhibit pancreatic lipase enzymes contributing to the development of obesity. The seeds were rich in uridine 5’-monophosphate, and total essential and non-essential free amino acids, whose contents correlated with the inhibitory activity toward α-amylase and α-glucosidase. The fruit flesh showed a high content of total free amino acids (hydroxy-L-proline, O-phosphoethanolamine, L-citruline). There was a positive correlation between antioxidant capacity and the content of polyphenolic compounds, nucleotide, and ability to inhibit pancreatic lipase, and between anti-hyperglycemic and free amino acids in fruits and fruit fractions. Therefore, the tested fruit of A. alnifolia and their fractions could be essential ingredients of new functional products and/or probiotic food.