Preparation, Multispectroscopic Characterization, and Stability Analysis of <i>Monascus</i> Red Pigments—Whey Protein Isolate Complex

Monascus red pigments (MRPs) are mainly used as natural food colorants; however, their application is limited due to their poor stability. To expand their areas of application, we investigated the binding constants and capacity of MRPs to whey protein isolate (WPI) and whey protein hydrolysate (WPH) and calculated the surface hydrophobicities of WPI and WPH. MRPs were combined with WPI and WPH at a hydrolysis degree (DH) of 0.5% to form the complexes (DH = 0.0%) and (DH = 0.5%), respectively. Subsequently, the structural characteristics of complex (DH = 0.5%) and WPI were characterized and the color retention rates of both complexes and MRPs were investigated under different pretreatment conditions. The results showed that the maximum binding constant of WPI with MRPs was 0.670 ± 0.06 U−1 and the maximum binding capacity was 180 U/g. Furthermore, the thermal degradation of complex (DH = 0.0%), complex (DH = 0.5%), and MRPs in a water bath at 50–100 °C followed a first-order kinetic model. Thus, the interaction of WPI with MRPs could alter the protein conformation of WPI and effectively protect the stability of MRPs

Correction of Iron Deficient Yellowing of Huangguogan by Different Application of Chelated Iron under Different Mulching Material

In this experiment, the asbestos chinensis was selected as the experimental material, and it was treated with black mulch, straw mulch, horticultural cloth mulch and river sand mulch, and compared with the control group to study the correction of iron deficiency yellowing of the leaves of Huangguogan. The results showed that the application of chelated iron under different mulching materials can significantly improve the photosynthesis index and leaf fluorescence characteristics of leaves, and correct the problem of iron deficiency yellowing of yellow fruit orange. The degree of correction of leaf iron deficiency yellowing by root-chelating iron was different under different mulching materials. In general, the correction effect of river sand mulch treatment was the most obvious, and the correction effect of black mulch was the worst. It was economical, practical, simple and convenient to correct the iron deficiency yellowing of the yellow fruit by mulching the material, and it had certain promotion value

Effects of Chelated Iron on Roots under Different Mulching Materials on Fruit Quality of Huangguogan

In this experiment, Huangguogan in Shimian County was selected as the experimental material, and the effects of different treatments on the fruit quality of Huangguogan were studied by mulching treatments with black film, straw, horticultural cloth and river sand. The results of this study showed that the application of chelated iron to the roots under different mulching materials could significantly improve the fruit quality, and the application of chelated iron to the roots under different mulching materials had different effects on fruit quality. The river sand mulching treatment had the highest single fruit weight, vertical and horizontal diameters, while CK had the lowest one. The four mulching treatments all increased the contents of total soluble solids, soluble sugar and sucrose. The river sand mulching treatment had the highest contents, which were 13.96%, 13.09 and 6.93 g.100 mL-1, respectively. There were significant differences in the titratable acid, vitamins C and sugar-acid ratio between the different mulching treatments, and the river sand mulching treatment had the highest effect. In general, the river sand mulching treatment had the best effect on promoting fruit quality, and plastic film mulching treatment had the worst effect