Repellency Mechanism of Natural Guar Gum-Based Film Incorporated with Citral against Brown Planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae)

Using of plant essential oil that coevolved as a defense mechanism against agriculture insects is an alternative means of controlling many insect pests. In order to repel brown planthoppers (BPHs), the most notorious rice insect pest, a new film based on guar gum incorporated with citral (GC film) was formulated, which was effective while being environmentally friendly. In this paper, the effect and mechanism of GC film repellency against BPHs were determined. Repellent activity test and olfactory reaction analysis showed that GC film had repellency effect against BPHs, with repellency of 60.00% and 73.93%, respectively. The result of olfactory reaction indicated that GC film repellency against BPHs relied on smell. EPG analysis showed the proportion and mean duration of np waveform were significantly higher than in CK and increased following the treatment concentration, which indicated that GC film affected the recognition of BPHs to rice. Further analysis by RNA sequencing analysis showed a total of 679 genes were significantly upregulated and 284 genes were significantly downregulated in the BPHs fed on the rice sprayed with GC film compared to control. Odorant-binding protein (OBP) gene 797 and gustatory receptor gene (GR)/odorant receptor (OR) gene 13110 showed a significant decrease in differential expression and significant increase in differential expression, respectively. There were 0.66 and 2.55 differential expression multiples between treated BPHs and control, respectively. According to the results described above, we reasoned that GC film repellency against BPHs due to smell, by release of citral, caused the recognition difficulties for BPHs to rice, and OBP gene 797 and GR/OR gene 13110 appeared to be the crucial candidate genes for GC film repellency against BPHs. The present study depicted a clear and consistent repellency effect for GC film against BPHs and preliminarily clarified the mechanism of GC film as a repellent against BPHs, which might offer an alternative approach for control of BPHs in the near future. Our results could also help in the development and improvement of GC films.

Effect of hydrocolloids on physicochemical properties, stability, and digestibility of Pickering emulsions stabilized by nanofibrillated cellulose

In this study, effect of hydrocolloids with different electrostatic characteristics, i.e. negatively charged xanthan gum (XG), positively charged chitosan (CH), and non-ionic guar gum (GG) on physicochemical properties, stability, and...

Comparison of the hydrocolloids application efficiency for stabilizing the foam of beer

Subject of research: technology of high gravity brewing, developed to improve production efficiency and reduce energy consumption. This technology has a wide range of benefits, from improving process economics to reducing environmental impact. Investigated problem: despite the presence of significant advantages, there are a number of problems in the technology of high gravity brewing that need to be solved. The main problem is to reduce the foam stability of the resulting beer, which, together with the appearance, aroma and taste, is the most important attributes of the quality of the beverage for the consumer. The stability and texture of the foam depend, among other things, on the quality of grain and hop raw materials, and the course of technological processes. Elevated levels of key malt proteins (LTP1, Z4 and Z7) and hop α-acids have a positive effect on foam quality. Yeast protease A has a negative effect. Yeast secretes this enzyme to a greater extent during fermentation of high gravity wort, which may be one of the reasons for the decrease in foam stability in high gravity brewing. High molecular weight a- and b-glucans with hydrophilic properties can play an important role in foam stabilization. They increase the viscosity of the liquid, slow down its drainage from the foam segments and thereby increase the foam retention. Main scientific results: the effect of hydrocolloids (highly methoxylated pectin, carboxymethyl cellulose, xanthan gum, guar gum, a mixture of xanthan and guar gum) on foam performance and beer filtration rate was investigated. The advantages of pectin as an additive allowing to stabilize beer foam, in particular, in high gravity - brewing, have been established. The recommended dosage of the additive is 0.4-1 g/hl. Highly methoxylated pectin is a good alternative to the currently widespread use of propylene glycol alginate. The area of practical implementation of the research results: brewing companies. Innovative technological product: highly methoxylated pectin as a stabilizing additive for beer foam. Scope of application of the innovative technological product: the use of highly methoxylated pectin as additives that stabilize beer foam, in particular in high gravity brewing.