Raspberries are important sources of bioactive compounds, whose synthesis is influenced by the fertilization system and the maturity stage. This study evaluated the effect of organic and conventional fertilization systems on raspberries at three maturity stages, pink, ripe, and overripe. Physicochemical characteristics, bioactive compounds (phenolic profile, vitamin C), antioxidant capacity (DPPH, FRAP, TEAC, and ORAC), phenolic-associated enzyme, phenylalanine ammonia lyase (PAL), and antioxidant enzymes (SOD, CAT, GPx, and APX) were evaluated. The physicochemical determination of the fruit did not reveal differences between fertilization systems. Regarding bioactive compounds, higher content of anthocyanins was found in organic raspberries at all maturity stages. Organic fertilization increased the content of ellagic acid and gallic acid at all stages of maturity. Higher content of caffeic, hydroxybenzoic, protocatechuic acid, and vitamin C was observed in organic raspberry at the overripe stage. Raspberries grown with organic fertilization exhibited higher values of antioxidant capacity by the DPPH, FRAP, and TEAC methods at all maturity stages. Raspberries under organic fertilization showed significantly greater activity of CAT, SOD, APX, GPX, and PAL. The present study suggests that organic fertilization induces oxidative stress causing an increase in antioxidant defense mechanisms, enhancing bioactive compound production, and improving antioxidant capacity in raspberries.

Volatile compounds contribute to aroma and flavor, these being the main sensory attributes in food acceptance. This work addresses the physicochemical, volatile compounds, polyphenols, and flavonoids content and, antioxidant activity of apple-raspberry (90/10%) juice treated by thermal and ultraviolet radiation (UV-C) alone or in combination with moderate heat-treatment. Nineteen volatile compounds were identified which experienced changes depending on the treatment. Compounds such as α-ionone and β-ionone, that contribute to raspberries characteristic aroma, were present in a greater concentration in the UV-C treatment and lower in the thermal treatment. Likewise, 2-methyl butyl acetate, which give a fruity-sweet aroma typical of apples was present in a greater concentration in the UV-C treatment. Regarding polyphenol content, control and combined treatment presented the greater concentrations. However, after twenty days of storage, control and combined treatment presented the lower flavonoid concentration. Nevertheless, at this time, treatments showed no variations in antioxidant activity. Yeast and mold and total aerobic mesophilic and psychrophilic counts were reduced in the heat and combined treatments. In conclusion, UV-C and moderate heat might successfully be used to process a stable apple-raspberry juice while maintaining its quality and safety.

Intensive horticultural crop production usually involves challenges from excessive application of fertilizer, mainly nitrogen (N). The effect of N fertilizer on the fruit quality and antioxidant status of two cherry tomato cultivars (Caballero and Victoria) under greenhouse conditions was performed. Nitrogen treatments were applied ranging from conditions comprising deficiency to toxicity (0, 15, 30, 45 and 60 mmol•L-1). Yield, weight, diameter, fruit quality, phenols, flavonoids, lycopene, ascorbic acid and antioxidant capacity were measured at physiological maturity of the fresh tomato fruits. N treatment with 30 mmol•L-1 produced the highest yield, fruit weight, firmness and diameter in both cultivars. However, increasing N from 30 to 60 mmol•L-1 increased the concentration of phenolics, flavonoids, and antioxidant capacity by 50, 125 and 33% in 'Caballero' tomatoes and by 60, 95 and 24% in 'Victoria' tomatoes, respectively. Lycopene content increased with increasing N doses (45 and 60 mmol•L-1) for 'Caballero' tomatoes, while vitamin C decreased as N concentration increased, suggesting that ascorbic acid acts by protecting against oxidative stress in tomato. The present work shows how N fertilization considerably influences yield and quality of tomatoes, as well as nutritional and healthy values.

Raspberry production represents an alternative for farmers in the temperate zones of Mexico. Due to the environmental impact caused by conventional agriculture, there is currently greater demand for organic food in the national and international market. To achieve this need, new fertilization techniques based on organic amendments are being tested. In the present study, yields and quality were evaluated over a 3-year period (2015, 2016 and 2017) as well as the phytochemical compounds of the production in 2017, with management of organic versus conventional fertilization of raspberry crop in open field in Cuauhtémoc, Chihuahua, Mexico. During the three years of study, the conventional fertilization system obtained higher yields, compared to the organic one, with values of 2,698 and 2,351 g per linear meter in 2015, 2,423 and 1,301 g per linear meter in 2016 and the data for 2017 were 3,077 and 2,550 g per linear meter, respectively. Regarding quality, the results showed no statistical differences between the two systems of production about colour, firmness, total soluble solids, titratable acidity and pH of the fruit. Differently the composition of phytochemicals, phenols, flavonoids, total anthocyanins and antioxidant capacity was better under the organic management. In conclusion, the conventional system showed higher yields, the quality of the fruits was not different between the two systems, while the levels of phytochemicals were higher with the organic farming. Therefore, it is important to continue the research in order to improve soil fertility and achieve higher yields under the organic management.

Raspberries are widely consumed; the taste of these is determined by the interaction between sugars, organic acids and a set of volatile compounds. Meanwhile, organic agriculture has developed rapidly as an alternative to conventional system, and has been driven by the demand for pesticide-free food that brings greater benefits to human health. However, this system can alter the integral quality of the fruit, including the aroma, which has been little studied. Therefore, the objective of this study was to evaluate the effect of the application of organic and conventional fertilizers, in the presence of volatile compounds synthesized in the cv. 'Heritage' raspberry, during two crop cycles. The qualitative profile of volatile compounds was analysed by mass gas chromatography, obtaining as a result that fertilization treatments significantly affected the emission of volatile compounds in the most abundant functional group (C13 norisoprenoids) 48.5 vs. 25.8% and 56.9 vs. 29.1% in conventional and organic, in 2017 and 2018, respectively (p <= 0.05). The crop cycle affected the concentration of aldehydes (11.2 vs. 30.6% in organic, in 2017 and 2018, respectively (p <= 0.05). Impact compounds such as alpha-ionone (13.92 vs. 9.08% and 25.34 vs. 9.17% in conventional and organic in 2017 and 2018, respectively) and beta-ionone (24.93 vs. 14.10% and 22.66 vs. 15.94% in conventional and organic in 2017 and 2018, respectively), presented greater abundance in conventional fertilization (p <= 0.05). Since there were changes in the volatile compounds, it is recommended to study whether the consumer perceives these changes.

Foliar sprays of growth regulators have commercial potential for improving the performance of some of the parameters associated with alternate bearing in pecan trees. The objective was to evaluate the behaviour of alternate bearing through analysis of seasonal variations in buds and leaflets of non-structural carbohydrates (glucose, fructose, sucrose, and starch), mineral nutrients (N-total, P, K⁺, Ca²⁺, Mg²⁺, Fe²⁺, Cu²⁺, Mn²⁺ and Zn²⁺), yield components (nut weight per kilogram and kernel percentage) and oxidative metabolism (superoxide dismutase, hydrogen peroxide, catalase, guaiacol peroxidase and antioxidant capacity) in cv. Wichita pecan trees in response to foliar applications of gibberellic acid (50 mg L⁻¹), calcium prohexadione (500 mg L⁻¹) or thidiazuron (10 mg L⁻¹). The experiment was of a completely randomized experimental design with five replicates. Foliar growth regulator (GRs) sprays help maintain the concentration of non-structural carbohydrates in the leaflets and buds between the evaluation years. With the exception of K⁺ (12.9 and 10.9 g kg⁻¹) and Zn²⁺ (45.1 and 30.5 mg kg⁻¹), the GRs did not show any effects on the concentrations of the foliar mineral nutrients. The results suggest foliar sprays of gibberellic acid improve the performance of parameters associated with alternate bearing, including oxidative metabolism.