Edmundo Mercado-Silva

Fruit development, harvest index and ripening changes of guavas produced in central Mexico

Abstract The variabilities in guava ( Psidium guajava cv. ‘Media China’) development period, and physical and chemical properties were determined for the spring–summer and autumn–winter harvest seasons in Mexico. At 20 day intervals, fruit diameter, weight, specific gravity (SG), total soluble solids content (SSC), ascorbic acid, titratable acidity, color and firmness were determined. Fruit growth showed a double sigmoidal pattern, with spring–summer fruit needing 130 days while autumn–winter fruit required 190 days to reach the ripe stage. Acidity decreased during development while ascorbic acid and SSC increased during the last stage of growth. Autumn–winter fruit had higher SCC, titratable acidity, and ascorbic acid concentrations than spring–summer fruit. The climacteric peaks in carbon dioxide and ethylene production were reached after 7–8 days in autumn–winter fruit as compared with 4–5 days in spring–summer fruit. The best maturity index was color: the mature green fruit could be harvested with L *, a * and Hue values of 65±3, −15±2 and 110±2, respectively. These values corresponded to fruit with yellowish green external color.

Effect of chemical elicitors on peppermint (Mentha piperita) plants and their impact on the metabolite profile and antioxidant capacity of resulting infusions.

Infusions are widely consumed all over the world and are a source of dietary antioxidants, which can be improved in plants using elicitors. The aim of this study was to evaluate the foliar application of salicylic acid (SA) (0.5, 1 and 2mM) or hydrogen peroxide (H2O2) (0.05, 0.1 and 0.5mM) on peppermint (Mentha piperita) plants and its effect on the metabolite profile and antioxidant capacity of resulting infusions. Whereas 2mM SA treatment improved plant growth parameters and metabolite profile (carbohydrates and amino acids), 0.5 and 1mM SA treatments increased phenolic compound concentration. Sinapic acid, rutin and naringin were detected only in SA treatments; antioxidant capacity was also improved. Regarding H2O2 treatments, no differences in plant growth parameters, metabolite profile or antioxidant capacity were found. Therefore, the application of SA to peppermint is recommended in order to improve bioactive compounds and the antioxidant capacity of infusions.

Effect of chemical stress on germination of cv Dalia bean (Phaseolus vularis L.) as an alternative to increase antioxidant and nutraceutical compounds in sprouts

The aim of this study was to determine the effect of chitosan (CH), salicylic acid (SA) and hydrogen peroxide (H2O2) at different concentrations on the antinutritional and nutraceutical content, as well as the antioxidant capacity of bean sprouts (cv Dalia). All elicitors at medium and high concentrations reduced the antinutritional content of lectins (48%), trypsin inhibitor (57%), amylase inhibitor (49%) and phytic acid (56%). Sprouts treated with CH, SA and H2O2 (7μM; 1 and 2mM, and 30mM respectively) increased the content of phenolic compounds (1.8-fold), total flavonoids (3-fold), saponins (1.8-fold) and antioxidant capacity (37%). Furthermore, the UPLC-ESI-MS/MS analysis showed an increase of several nutraceutical compounds in bean sprouts treated with SA such as coumaric (8.5-fold), salicylic (115-fold), gallic (25-fold) and caffeic (1.7-fold) acids, as well as epigallocatechin (63-fold), rutin (41-fold) and quercetin (16.6-fold) flavonoids. The application of elicitors in bean seed during sprouting enhances their nutraceutical properties.

Development of chilling injury in five jicama cultivars

Five commercially important jicama (Pachyrhizus erosus) cultivars (‘Agua Dulce’, ‘Cristalina’, ‘San Juan’, ‘San Miguelito’, and ‘Vega de San Juan’) were stored at 10°C and 13°C to study postharvest quality changes and chilling susceptibility. Decay development, weight loss after storage, internal color and texture, respiration rates and ion leakage were the parameters used to evaluate differences in chilling susceptibility. All cultivars were very chilling sensitive, with symptoms of injury occurring after 1 week at 10°C plus 1 week at room temperature. Roots of cvs ‘Vega de San Juan’ and ‘San Miguelito’ were the most and least tolerant to 10°C storage, respectively. Roots stored at 13°C showed few internal quality changes over a 5-month period, although weight loss exceeded 35%.

Low temperature conditioning of garlic (Allium sativum L.) “seed” cloves induces alterations in sprouts proteome

Low-temperature conditioning of garlic “seed” cloves substitutes the initial climatic requirements of the crop and accelerates the cycle. We have reported that “seed” bulbs from “Coreano” variety conditioned at 5°C for 5 weeks reduces growth and plant weight as well as the crop yields and increases the synthesis of phenolic compounds and anthocyanins. Therefore, this treatment suggests a cold stress. Plant acclimation to stress is associated with deep changes in proteome composition. Since proteins are directly involved in plant stress response, proteomics studies can significantly contribute to unravel the possible relationships between protein abundance and plant stress acclimation. The aim of this work was to study the changes in the protein profiles of garlic “seed” cloves subjected to conditioning at low-temperature using proteomics approach. Two sets of garlic bulbs were used, one set was stored at room temperature (23°C), and the other was conditioned at low temperature (5°C) for 5 weeks. Total soluble proteins were extracted from sprouts of cloves and separated by two-dimensional gel electrophoresis. Protein spots showing statistically significant changes in abundance were analyzed by LC-ESI-MS/MS and identified by database search analysis using the Mascot search engine. The results revealed that low-temperature conditioning of garlic “seed” cloves causes alterations in the accumulation of proteins involved in different physiological processes such as cellular growth, antioxidative/oxidative state, macromolecules transport, protein folding and transcription regulation process. The metabolic pathways affected include protein biosynthesis and quality control system, photosynthesis, photorespiration, energy production, and carbohydrate and nucleotide metabolism. These processes can work cooperatively to establish a new cellular homeostasis that might be related with the physiological and biochemical changes observed in previous studies.

Metabolite profile, antioxidant capacity, and inhibition of digestive enzymes in infusions of peppermint (Mentha piperita) grown under drought stress.

Peppermint (Mentha piperita) infusions represent an important source of antioxidants, which can be enhanced by inducing abiotic stress in plants. The aim of this study was to evaluate the effect of drought stress on peppermint cultivation as well as the metabolite profile, antioxidant capacity, and inhibition of digestive enzymes of resulting infusions. At 45 days after planting, irrigation was suppressed until 85 (control), 65, 35, 24, and 12% soil moisture (SM) was reached. The results showed that 35, 24, and 12% SM decreased fresh (20%) and dry (5%) weight. The 35 and 24% SM treatments significantly increased total phenolic and flavonoid contents as well as antioxidant capacity. Coumaric acid, quercetin, luteolin, and naringenin were detected only in some drought treatments; however, in these infusions, fewer amino acids and unsaturated fatty acids were identified. The 24 and 12% SM treatments slightly improved inhibition of pancreatic lipase and α-amylase activity. Therefore, induction of moderate water stress in peppermint is recommended to enhance its biological properties.

Pitaya—Hylocereus undatus (Haw)

Abstract Dragon fruit or pitahayas or are native to southern Mexico and Central America. Due to their attractive color and flavor, the world production is increasing quickly and new fruit crops for dry lands are under development. Today it is commercially cultivated in the Bahamas, Bermuda, Indonesia, Colombia, Israel, Philippines, Maymar, Malaysia, Mexico, Nicaragua, northern Australia, Okinawa (Japan), Sri Lanka, southern China, southern Florida, Taiwan, Thailand, Vietnam, and the West Indies. This chapter reviews the botanical aspects, fruit physiology and potential commercial applications of dragon fruit.