种植密度和施氮量对鲜食糯玉米果穗性状的影响研究

采用裂区设计研究了不同种植密度和施氮量对鲜食糯玉米果穗性状的影响,结果表明,随种植密度提高,鲜食糯玉米果穗长度有所下降,果穗直径显著变小,果穗行粒数降低,秃尖长度逐渐增加,单果穗鲜重显著下降,但果穗籽粒行数和穗轴直径与种植密度无关。果穗长度、果穗籽粒行数、穗轴直径、单穗重均以中等施氮量最大,果穗秃尖度以中等施氮量最低。种植密度和施氮量对果穗主要性状也有明显的交互效应。     

Sonoprocessing improves phenolics profile,antioxidant capacity,structure, and product qualities of purple corn pericarp extract

For the first time, purple corn pericarp (PCP) was converted to polyphenol-rich extract using two-pot ultrasound extraction technique. According to Plackett-Burman design (PBD), the significant extraction factors were ethanol concentration, extraction time, temperature, and ultrasonic amplitude that affected total anthocyanins (TAC), total phenolic content (TPC), and condensed tannins (CT). These parameters were further optimized using the Box-Behnken design (BBD) method for response surface methodology (RSM). The RSM showed a linear curvature for TAC and a quadratic curvature for TPC and CT with a lack of fit > 0.05. Under the optimum conditions (ethanol (50%, v/v), time (21 min), temperature (28 °C), and ultrasonic amplitude (50%)), a maximum TAC, TPC, and CT of 34.99 g cyanidin/kg, 121.26 g GAE/kg, and 260.59 of EE/kg, respectively were obtained with a desirability value 0.952. Comparing UAE to microwave extraction (MAE), it was found that although UAE had a lower extraction yield, TAC, TPC, and CT, the UAE gave a higher individual anthocyanin, flavonoid, phenolic acid profile, and antioxidant activity. The UAE took 21 min, whereas MAE took 30 min for maximum extraction. Regarding product qualities, UAE extract was superior, with a lower total color change (ΔE) and a higher chromaticity. Structural characterization using SEM showed that MAE extract had severe creases and ruptures, whereas UAE extract had less noticeable alterations and was attested by an optical profilometer. This shows that ultrasound, might be used to extract phenolics from PCP as it requires lesser time and improves phenolics, structure, and product qualities.