Decision-tree-based ion-specific dosing algorithm for enhancing closed hydroponic efficiency and reducing carbon emissions.

The maintenance of ion balance in closed hydroponic solutions is essential to improve the crop quality and recycling efficiency of nutrient solutions. However, the absence of robust ion sensors for key ions such as P and Mg and the coupling of ions in fertilizer salts render it difficult to effectively manage ion-specific nutrient solutions. Although ion-specific dosing algorithms have been established, their effectiveness has been inadequately explored. In this study, a decision-tree-based dosing algorithm was developed to calculate the optimal volumes of individual nutrient stock solutions to be supplied for five major nutrient ions, i.e., NO3, K, Ca, P, and Mg, based on the concentrations of NO3, K, and Ca and remaining volume of the recycled nutrient solution. In the performance assessment based on five nutrient solution samples encompassing the typical concentration ranges for leafy vegetable cultivation, the ion-selective electrode array demonstrated feasible accuracies, with root mean square errors of 29.5, 10.1, and 6.1 mg·L-1 for NO3, K, and Ca, respectively. In a five-step replenishment test involving varying target concentrations and nutrient solution volumes, the system formulated nutrient solutions according to the specified targets, exhibiting average relative errors of 10.6 ± 8.0%, 7.9 ± 2.1%, 8.0 ± 11.0%, and 4.2 ± 3.7% for the Ca, K, and NO3 concentrations and volume of the nutrient solution, respectively. Furthermore, the decision tree method helped reduce the total fertilizer injections and carbon emissions by 12.8% and 20.6% in the stepwise test, respectively. The findings demonstrate that the decision-tree-based dosing algorithm not only enables more efficient reuse of nutrient solution compared to the existing simplex method but also confirms the potential for reducing carbon emissions, indicating the possibility of sustainable agricultural development.

Evaluation of In Vitro Antioxidant Activity of the Water Extract Obtained from Dried Pine Needle (Pinus densiflora).

Antioxidant activities of water extracts obtained from dried pine needle (Pinus densiflora) were measured at 0, 4, 20, 100, 500, 1,000, and 1,200 ppm and compared with those of phenolic compounds of butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, ferulic acid, and α-tocopherol. The activity was determined as the ability to scavenge 1,1-diphenyl-2-picrylhydrazyl radical and hydrogen peroxide, reductive power, and inhibition of lipid peroxidation in a linoleic acid system using the ferric thiocyanate method and thiobarbituric acid method, respectively. Pine needle water extract (PNWE) exhibited antioxidant activity in a concentration-dependent mode at the same parameters mentioned above, and a significant difference (P<0.05) was observed at 1,000 ppm. The protective activity of PNWE as a potent antioxidant in a non-cellular system was compared with that of phenolics at 150.67 µg/mL in the two assays using biological cellular systems, namely 2,2'-azobis(2-amidinopropane) dihydrochloride-initiated hemolysis and Fe2+-induced lipid peroxidation, using rat red blood cells and rat brain homogenate, respectively. The PNWE showed a strong power comparable to those of commercial phenolic compounds in biological systems. These results indicated that the protective activity of PNWE could be due to the presence of naturally-occurring phenolic compounds, which act as potent in vitro antioxidants in both non-cellular and cellular systems.

Antioxidant activity and total phenolic content in shiitake mycelial exudates.

Exudates (DE) secreted from two shiitake mushroom mycelia (strains 1358 and L5458) were evaluated for their antioxidative properties and phenolic content. 1358DE and L5458DE showed distinct antioxidant activity in different in vitro assays, including scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, hydroxyl radical, superoxide anions and hydrogen peroxide; the ability to chelate ferrous ions; reducing power; hemolysis inhibition activity in rat erythrocyte; and lipid peroxidation inhibition (IC50 values of 1358DE and L5458DE were 3.3 and 132.6; 44.5 and > 1000; 26.9 and 53.7; 153.6 and > 175.0; 176.0 and 521.0; 26.7 and 746.4; 47.8 and 736.9; and 3.1 and > 1000 microg/mL, respectively). Their total phenolic content was 237.33 and 24.08 mg gallic acid equivalent (GAE)/g of dry DE, respectively. Overall, these results show that 1358DE generally possesses better antioxidant properties than L5458DE, possibly due to its larger total phenolic content. Shiitake mushroom mycelial exudates, particularly of 1358DE, could be a good source of natural antioxidants.

Cytoprotective effect of polysaccharide isolated from different mushrooms against 7-ketocholesterol induced damage in mouse liver cell line (BNL CL. 2).

Cytoprotective ability of polysaccharides isolated from different edible mushrooms was investigated on the 7-ketocholesterol-induced damaged cell line. Polysaccharide extracts from six different edible mushrooms-Flammulina velutipes, Peurotus ostreatus, Lentinus edodes, Agrocybe aegerita, Agaricus blazei, and Cordyceps militaris- were prepared by hot water extraction and alcohol precipitation. Cytoprotective ability was evaluated by measuring the viable cells of the normal embryonic liver cell line (BNL CL. 2) in the presence of 7-ketocholesterol. At 80 microg/mL of 7-ketocholesterol, cytotoxicity was very high with a loss of 98% of viable cells after 20 h of incubation. With the addition of 200 microg/mL of each polysaccharide isolate to the cell line containing 80 microg/mL of 7-ketocholesterol, polysaccharide isolates from both Flammulina velutipes and Peurotus ostreatus could significantly inhibit the 7-ketochoelsterol-induced cytotoxicity in the cells. But other polysaccharide isolates were not effective in inhibiting cell damage caused by the oxLDL-induced cytotoxicity.

Enhancement of bromophenol levels in aquacultured silver seabream (Sparus sarba).

The effect of the addition of marine algae in fish feed on the levels of bromophenols in fish flesh was studied. These bromophenols include 2-bromophenol, 4-bromophenol, 2,4-dibromophenol, 2,6-dibromophenol, and 2,4,6-tribromophenol. Two types of algae-containing fish feeds with 30% Padina arborescens and 30% Sargassum siliquastrum were developed. The total bromophenol contents of these feeds were 132 and 340 ng/g respectively, which were significantly higher than that of the control feed (8.9 ng/g) (ANOVA, p < 0.05). Silver seabream was used as the model fish for the feeding experiment. Bromophenol contents of both fish gut and flesh were monitored at 2-week intervals throughout the 8-week period. Two-way ANOVA showed that only the 30% S. siliquastrum-containing feed significantly (p < 0.05) increased the total bromophenol content in the fish flesh with time. This also produced sensorial differences in the fish flesh.

Aroma impact components in commercial plain sufu.

Volatile components of three commercial plain sufus or fermented soybean (Glycine max) curds (A-C) were extracted by a supercritical fluid extraction apparatus and analyzed by gas chromatography-mass spectrometry. A total of 83 compounds were found, of which 68 compounds were common among the three samples. Samples A, B, and C had 76, 75, and 74 components, respectively. Alcohols (17), acids (15), and esters (16) were the major classes. The rest of the classes were miscellaneous compounds (9), aldehydes (7), alkanes (5), aromatic compounds (5), ketones (3), furans (2), S-containing compounds (2), and other N-containing compounds (2). Gas chromatography-flame ionization detection-olfactometry analyses identified 17 potent odorants with different odor descriptions such as sour, sweet, fruity, coconut-like, and meaty. Fourteen odorants were further pinpointed by omission experiments among the 17 to be critical to the odor of commercial plain sufu. Acetic acid, methional, ethyl (Z,Z)-9,12-octadecadienoate, ethyl (Z)-9-ocatadecenoate, and 3-methylbutanoic acid were some of the potent odorants found.

Odor-active headspace components in fermented red rice in the presence of a monascus species.

Headspace components from rice and agar with (experimental) and without (control) inoculation with a Monascus spp. were investigated. Kinetics studies were carried out. Using rice as a substrate, 10 and 19 compounds were found for the control and the experimental groups, respectively, at day 14. Experimental group compounds were composed mainly of alcohols, ketones, and esters, whereas control group compounds were composed of aldehydes and ketones. With agar as a substrate, only five and three components were found in the control and experimental groups, respectively. Five alcohols, four esters, two ketones, and one furan with odor activity values (OAV) >1 dominated the overall flavor of the product. With liquid inoculation, the first six components with high OAVs were in the following order: 3-methyl-1-butanol (17) > ethanol (14) > ethyl acetate (10) > 2-methyl-1-propanol (15) > ethyl butanoate (11) > 3-methylbutyl acetate (13). Kinetic studies showed that most compounds reached their maximum concentrations at 10-12 days. Many compounds identified in the model red rice were reported in commercial red sufus, and several appeared to contribute solely by red rice.

Seasonal distribution of bromophenols in selected Hong Kong seafood.

Selected seafood including rabbitfish (Siganus canaliculatus), brown-spotted grouper (Epinephelus areolatus), clam (Tapes philippinarum), oyster (Ostrea rivularis), shrimp (Penaeus japonicus), and crab (Charybdis feriatus), commonly found in the Hong Kong wet market, was monitored for their distribution and seasonal variations of their bromophenol contents. Specifically, 2-bromophenol (1). 4-bromophenol (2). 2,4-dibromophenol (3). 2,6-dibromophenol (4). and 2,4,6-tribromophenol (5). were monitored due to their flavor impact to seafood. All samples of marine origin contained bromophenols throughout a year. Crab had the highest concentration of total bromophenol content throughout the season. Concentrations of compounds 1, 4, and 5 in the local seafood were generally higher than that found in the literature values to provide characteristic flavor, but lower than that required to cause off-flavor. Variations of the flavor impact of bromophenols in seafood during a season could be better shown by their flavor values. Distribution and seasonal variations of bromophenol content in seafood coincided well with the seasonal growth cycle of the bromophenol synthesizing seaweeds, e.g. brown algae, in the region suggesting the abundant source of bromophenols in the environment might have a high impact on the quantity of bromophenols found in seafood.

Seasonal variations of bromophenols in brown algae (Padina arborescens, Sargassum siliquastrum, and Lobophora variegata) collected in Hong Kong.

Distributions and seasonal variations of the key seafood flavor compounds including 2-bromophenol, 4-bromophenol, 2,4-dibromophenol, 2,6-dibromophenol, and 2,4,6-tribromophenol in three species of brown algae (Padina arborescens, Sargassum siliquastrum, and Lobophora variegata) found in Hong Kong waters were investigated. Bromophenols were extracted by simultaneous steam distillation and solvent extraction apparatus and analyzed by gas chromatography-mass spectrometry. On a dried weight basis, the total bromophenol content (TBC) determined varied widely with seasons (from 40.9 to 7030 ng/g). The TBCs detected were higher in winter and lower in summer. Except for 2-bromophenol, the rest of the bromophenols were detected in all of the algal samples. The TBC of L. variegata was generally the highest among all of the algae collected. Relatively high concentrations of bromophenols in algae supported the fact that marine algae were major producers of bromophenols in the marine environment.