As the EtOH concentration increases during fermentation, the solubility of polyphenols, including the larger and more hydrophobic phenolics, will increase. Moreover, a decrease in the polarity of the solution by the presence of ethanol can disrupt hydrophobic interaction, increasing the molecules in solution. To the best of our knowledge, there is only one other study that has investigated the decrease in anthocyanin concentration over time when in contact with skin cell wall analogues. No known study has analyzed the synergistic effect of EtOH and temperature on the adsorption of anthocyanins overtime as well as their influence on adsorption to different cell wall material components. In this work, the effects of temperature and EtOH concentration on the kinetics of anthocyanin adsorption and desorption interactions were investigated with five different CWM compositions. Using temperatures of 15 ◦C and 30 ◦C and model wine with EtOH content of 0% and 15% over a time period of 120 min, the adsorption and desorption interactions of five anthocyanin-glucosides with CWM were analyzed.Ash, lipid content, proteins, uronic acid, soluble polysaccharides, cellulose, Klason lignin, and non-cellulosic glucose of all the different CWMs isolated were determined . In all cases, the ash content was lower than 5%. This agrees with previous characterization of CWM from different cultivars as the main components of CWM are cellulose, pectin, round plastic pot hemicellulose and lignin. CWM4 and CWM5 had slightly higher protein content due to the absence of the phenol wash during the isolation process. CWM2 exhibited a higher protein content than CWM1 and CWM3 potentially due to the linking of oligosaccharides to proteins.
CWM1 and CWM3, although lower than the other CWM preparations, still contained a significant amount of protein due the fact that the phenol buffer treatment only removes cytoplasmic proteins. Other types of proteins may exist within the structure of the CWM matrix such as glycoproteins and wall proteins. Regarding lipid concentration, CWM3 and CWM5 presented the highest values due to the absence of the MeOH/chloroform extraction during the isolation process. As for soluble polysaccharide content, the CWM that were extracted with HEPES buffer presented very low amounts. The small amounts found could be explained by the existence of glycolipids and glycoproteins on the CWM that were not removed during the different washes. The difference in soluble polysaccharides between CWM2 and CWM5 may be the result of consecutive washings of CWM2 to remove other CWM components resulting in inadvertent removal of polysaccharides. The amounts of Klason lignin, cellulosic glucose and non-cellulosic glucose as well as uronic acids are comparable for all types of CWM analyzed, as they are not influenced by any of the extraction solvents used during the different isolation steps. The total polyphenolic content was less than 5% in all cases.Regarding the type of anthocyanin, no differences in binding were found between non-acetylated and acetylated anthocyanin. Nevertheless, the detailed anthocyanin profile showed that delphinidin- 3-glucoside and petunidin-3-glucoside had a larger percentage adsorbed compared to the rest of the molecules analyzed at all the conditions analyzed. The adsorption percentage of delphinidin 3-glucoside ranged from 20% to 85% depending on the experimental conditions, and malvidin 3-glucoside adsorption percentage ranged from 10% to 70%. This trend was found for all the types of CWM suggesting that the presence of hydroxyl groups on the anthocyanin contribute to the potential hydrogen bonding between the anthocyanin molecules and the CWM polysaccharides that influence adsorption kinetics. Similar to these findings, previous studies found that non-acetylated and acetylated anthocyanin showed similar behavior in the presence of skin CWM.
Additionally, Vasserot et al. obtained similar results regarding polarity on the study of adsorption of five monoglycoside anthocyanins onto yeast CWM in the presence of alcohol. Table 2 shows the percentage of adsorption of individual anthocyanin species onto CWM1 under all the conditions analyzed. In the absence of EtOH the order of anthocyanins was: delphinidin-3-glucoside, petunidin-3-glucoside, malvidin-3-glucoside, malvidin-3-acetyl-glucoside and peonidin-3-glucoside. However, when EtOH concentration increases to 15%, the order of anthocyanins changes to delphinidin- 3-glucoside, petunidin-3-glucoside, peonidin-3-glucoside, malvidin-3-glucoside and malvidin-3-acetyl-glucoside. Adsorption fluctuations could be due to the disruption of hydrogen bonds by EtOH. Additionally, the decrease in polarity of the solution in the presence of EtOH increased the concentration of the less polar molecules in solution. The presence of EtOH did not have a large impact on the adsorption process, this could be potentially due to the fact that the maximum concentration tested was 15%. Furthermore, the order of anthocyanin adsorption was not impacted by temperature changes between 15 and 30 ◦C. This trend was observed for all the different CWM matrixes tested.Significant differences in the binding response between anthocyanin and the CWM at different conditions were determined from triplicate experiments using a multi-way analysis of variance . The results indicated that all the variables have a significant impact on the adsorption process . It has been observed that anthocyanin molecules can undergo thermal degradation by breaking the O-glycosidic bond. In this study, the potential presence of break-down products produced by the degradation of anthocyanins was investigated by means of LC-DAD-MS/MS. In all samples, all screened break-down compounds fell below the LOD indicating changes in anthocyanin concentration were due to adsorption. This could be due to the fact that 30 ◦C is a low temperature to breakdown the short time period of the experiment .
Desorption assays were performed under the same sets of temperature and EtOH as those for the adsorption experiments. The rates of the desorption process were faster than adsorption reaching a plateau within the first 30 min. Figure 3 shows the kinetics of desorption for CWM2 at all the conditions tested. As can be observed, the desorption kinetics depended not only on the conditions of the experiment but also on the amount of anthocyanin initially adsorbed onto the CWM. Concerning the type of anthocyanin, delphinidin-3-glucoside and petunidin-3-glucoside showed the lowest percentage of desorption suggesting the breakdown of hydrophobic interactions by the solvent prior to hydrogen bonds. Similar trends were found for the other CWMs studied. Table 3 shows the amount of anthocyanin molecules adsorbed at the beginning of the desorption experiment, the amount released after 120 min and the percentage desorbed after 120 min for each of the experiments performed. At low temperature, round pot the presence of alcohol resulted in an increase in the desorption percentage likely due to the disruption of the hydrophobic interactions or an increase in the solubility of anthocyanins in solution. A similar trend was observed when the temperature was increased in the absence of alcohol. However, at a higher temperature in the presence of EtOH this trend was not noted , potentially due to the expansion of the Molecules CWM and the low amount adsorbed of anthocyanin adsorbed under these conditions.Interactions between anthocyanin molecules and skin CWM can occur spontaneously and rapidly. For all the experiments performed the maximum adsorption was reached after 60 min, suggesting no influence of the composition of the CWM on the rate of adsorption. However, the presence of different macromolecules on the CWM does result in the modification of the binding capacity of the CWM. The amount of adsorbed molecules was found to be positively influenced by the absence of large macromolecules blocking the binding sites, attaining the maximum percentage of adsorption with the cleanest CWM . Both temperature and alcohol percentage had a significant impact on adsorption. All the experiments showed that an increase in temperature and ethanol produces a decrease in the adsorption percentage potentially due to the increase of the solubility of the pigments in the model wine. Anthocyanin polarity appeared to be important as the more polar molecules showed a higher percentage of adsorption. Desorption was mostly influenced by temperature and EtOH increasing the desorption rate—no trends were found regarding CWM composition. The results suggest the presence of different types of interactions between the CWM and the anthocyanin molecules. The existence of a base layer with the strongest interactions between the anthocyanin and the CWM cellulose/pectin network has been previously reported. Additionally, hydrogen bonding between the hydroxyl groups of pigments and the oxygen atoms of the cross-linked ether bonds of sugars present in the CW polysaccharides as well as hydrophobic interactions take place. Additionally, concentration related π-π interactions between anthocyanin molecules can potentially form anthocyanin complexes, which can potentially stack on to the CWM. CWM is also a complex porous structure, which may trap molecules in solution. Our findings are in good agreement with the phenomena routinely observed in wineries where wines with higher alcohol content or fermented at higher temperatures extract more phenolics and color .
This work shows that a high concentration of phenolics in wine depends not only on grape phenolic composition but also on temperature and EtOH conditions during fermentation as well as adsorption/desorption interactions of the phenolics with solids in the fermentor. Additionally, differences in the composition of grape CWM could directly affect both the release and adsorption processes, leading to a different final wine phenolic profile. The coffee trade is, after petroleum, the most valuable commodity globally in terms of total value, and yet it faces severe issues with pests. Te coffee sector had a retail market value of USD 83 billion, providing jobs for 125 million people on 12.5 million farms worldwide, mostly smallholder farms including 22 Low Human Development Countries . In 2017, 70 per cent of total coffee production worth USD 19 billion was exported. Te coffee berry borer Hypothenemus hampei is the most important pest of coffee worldwide causing immense economic losses in the main production areas of Central and South America, Indonesia, South East Asia, Hawaii, and Puerto Rico where infestation levels are variable but can reach up to 95%. Like many ambrosia beetles that form galleries for the development of progeny, mated adult CBB females bore into coffee berries to form galleries. CBB is not effectively controlled by the action of parasitoids, the establishment of which in new world coffee has proven difficult. An early multitrophic study of the coffee agroecosystem using the mechanistic physiologically based demographic modeling approach demonstrated that CBB parasitoids alone were not efficient in controlling CBB. Those findings were confirmed in subsequent restudy of the coffee system using PBDMs that introduced extensive new data from Colombia on the dynamics of coffee growth and development, the effects of solar radiation on foral bud initiation; effects of leaf water potential on breaking dormancy in flower buds; effects of low temperature on photosynthesis and defoliation; enhanced CBB biology and population dynamics including the effects of intraspecific competition, temperature and rainfall on CBB adult emergence; the impact of baited traps for CBB control; and refinements of parasitoid biology and interactions . These PBDMs provided excellent fits to the field data on coffee growth and development, on CBB dynamics, and provide a solid base for evaluating the efficacy of the four parasitoids singly and in combinations in mitigating the impact of CBB . In this paper, we add to the PBDM system the following factors: Conventional cultural practices using intensive harvesting, cleanup of abscised berries, and insecticides, and biopesticides based on two entomopathogenic fungal species , and two entomopathogenic nematodes , and the interaction of all control components. Te scope of the coffee system components included in the analysis are depicted in Fig. 1. Field data are time consuming and prohibitively expensive to collect and are unlikely to yield global conclusion across time and geographic space. Realistic mechanistic weather driven PBDMs used as the objective function in our bio-economic analysis are not constrained by such limitations. There are two main periods of fruit ripening in the Colombian coffee region, April–June, and September–November, but occasional dry periods occur in between that induce the presence of ripe fruits on the plant and abscised fruit on the ground. Common cultural practices for CBB control are periodic harvesting of overripe and dry fruits on the tree and cleanup of abscised fruit on the ground . Insecticides are commonly used for CBB control, causing mortality of free-flying adult females before they bore into berries. Te action of insecticides decreases over 15 days from the time of application. Benavides and Arévalo and Benavides et al. recommended, that chemical control should start 90 days after flowering, when berries have a dry matter content of approximately 20%, and that it should be continued if infestation levels are higher than 2%. However, because berries are often present year around in Colombia, it is difficult to apply this criterion for initiating chemical control.