Organic Acid-Catalyzed Subcritical Water Hydrolysis of Immature Citrus unshiu Pomace

Immature Citrus unshiu pomace (ICUP) was hydrolyzed under organic acid-catalyzed, subcritical water (SW) conditions to produce flavonoid monoglucosides (hesperetin-7-O-glycoside and prunin) and aglycons (hesperetin and naringenin) with high biological activities. The results of single-factor experiments showed that with 8 h of hydrolysis and an increasing citric acid concentration, the yield of flavonoid monoglucosides (hesperetin-7-O-glycoside and prunin) increased from 0 to 7% citric acid. Afterward, the hesperetin-7-O-glycoside yield remained constant (from 7 to 19% citric acid) while the pruning yield decreased with 19% of citric acid, whereas the aglycon yield increased continuously. In response surface methodology analysis, a citric acid concentration and hydrolysis duration of 13.34% and 7.94 h were predicted to produce the highest monoglucoside yield of 15.41 mg/g, while 18.48% citric acid and a 9.65 h hydrolysis duration produced the highest aglycon yield of 10.00 mg/g. The inhibitory activities of the SW hydrolysates against pancreatic lipase (PL) and xanthine oxidase (XO) were greatly affected by citric acid concentration and hydrolysis duration, respectively. PL and α-glucosidase inhibition rates of 88.2% and 62.7%, respectively, were achieved with 18.48% citric acid and an 8 h hydrolysis duration, compared to 72.8% for XO with 16% citric acid and 12 h of hydrolysis. This study confirms the potential of citric acid-catalyzed SW hydrolysis of ICUP for producing flavonoid monoglucosides and aglycons with enhanced enzyme inhibitory activities.

Study of the Annealing Effect of Starch/Polyvinyl Alcohol Films Crosslinked with Glutaraldehyde

Films were fabricated using a mixture of polyvinyl alcohol (PVA)/cassava starch and incorporated citric acid in a concentration range between 5% and 40%. The films were annealed through thermal treatment in a temperature range between 30 °C and 90 °C with 0.3% glutaraldehyde incorporated as the crosslinking agent. This study presents the results of an experimental design analyzed using the response surface methodology. The multiple regression analysis allowed us to obtain the second-order models, which relate the annealing factors and citric acid concentration to Maximum Tensile Strength (MTS), Young’s Modulus (YM), and the Maximum Elongation at Break (MEB). The optimization and validation of the obtained model were carried out with error values below 10.08% for all the response variables, indicating that the response surface methodology and optimization were correct. Finally, as a complementary analysis, the differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR) tests were carried out, which revealed a higher packaging of the heat-treated films and verified their crosslinking.

Karakteristik Fisikokimia dan Sensoris Selai Bengkuang (Pachyrhizus Erosus L.) dengan Penambahan Pektin dan Asam Sitrat pada Berbagai Konsentrasi

This research aimed to figure out the effect of differences in concentration of citric acidand pectin and their interactions on the content of proximate and sensory of jam.The research was conducted using a completely randomized design (CRD) with a factorial pattern consisting of two factors.The first factor was the comparison of thethree levels of citric acid (A) concentration:1% (A1), 2% (A2),and 3% (A3) of the total ingredients for making jam.The second factor was pectin concentration (P) in 4 levels: 0.83%(P1), 1.0% (P2), 1.17% (P3), and 1.34% (P4) of the total ingredients for making jam.The chemical parameters tested included moisture content, fiber content, ash content, and antioxidant, while the physical parameters included pH and viscosity.The sensory test assessments includedaroma, taste, color, preference, and spreadability.The results indicated that the comparison of the concentration of citric acid (A) had a significant effect on the proximate analysis of the pH variable; however, it had no significant effect on several other variables:moisture content, crude fiber content, ash content, viscosity, and antioxidant.The results of the sensory test did not significantly affect the variables of aroma, taste, color, preference, and spreadability.In addition, the treatment of pectin (P)concentration ratio had a significant effect toward proximate analysis on water content and viscosity variable, but it had no significant effect on the variables offiber content, ash content, pH, and antioxidant.Meanwhile, the sensory test had a significant effect on the preference variable and had no significant effect on the aroma, taste, color, and spreadibilityvariables.The treatment interactions (AxP) significantly affectedproximate analysis on pH and viscosity variables.However, it did not affect the variable of water content, fiber content, ash content, and antioxidantsignificantly.The sensory test results hada significant effect onpreference variable.The best treatment wason the use of 1% citric acid concentration and 0.83% pectin concentration (A1P1) with 42.63% water content, 37.54% fiber content, 0.25% ash content, pH of 3.30, a viscosity of 8.49 cP, and an antioxidant of 9.22%.The treatment resulted in the aroma of 3.67 (delicious), taste of 4.67 (delicious), color of 4.00 (yellowish white), preference of 5.00 (likevery much), and spreadability 3.67 (easy).

Recovery of cobalt and molybdenum from spent catalyst using citric acid

Valuable metals play essential roles in various industrial sectors, such as petroleum, petrochemical, and steel industries. Potential secondary resources of these metals can be obtained from spent catalysts, which are a solid waste of the chemical and oil industries. Spent catalysts contain valuable metal compounds such as nickel (Ni), vanadium (V), cobalt (Co), molybdenum (Mo), rhodium (Rh), platinum (Pt), alumina (Al), etc. In this research, the recovery of cobalt and molybdenum from the spent catalyst of Pertamina Refinery Unit IV, Cilacap, Indonesia, was leaching using citric acid. Samples of spent catalyst were analyzed using EDXRF prior to the leaching process. Citric acid at various concentrations of 1.0, 1.5 and 2 M was used as a leaching agent. The leaching experiment was carried out for 300 minutes and sampling was undertaken at 1, 3, 5, 15, 30, 90 and 300 minutes. Each sample was separated between solid and liquid phases using a centrifuge at 400 rpm for 10 minutes. For analysis, 2 ml of the liquid phase was taken and the cobalt and molybdenum concentrations were analyzed using ICP-OES. It was found that at higher the citric acid concentration and temperature, the recovery of cobalt and molybdenum was also higher. The best leaching condition is obtained at a citric acid concentration of 2 M and 60ºC, where recovery of cobalt and molybdenum were 17.35% and 2.27%, respectively.

Biological production of citric acid in submerged culture of Aspergillus niger using cassava pulp wastes

Utilization of cassava pulp wastes for citric acid production was investigated using Aspergillus niger in a submerged culture. A series of experiments were designed on various fermentation parameters to establish the optimal conditions for citric acid production from cassava pulp. This study revealed that production parameters such as cassava pulp concentration, initial pH, incubation temperature, agitation, and nitrogen source and fermentation period had effect on the amount of citric acid produced from cassava pulp. Citric acid concentration increased as the concentration of cassava pulp increases up to 20% with maximum citric acid concentration of 14.9 ± 0.413 g/l after 120 hours of fermentation. pH 5.5 was the optimum with maximum citric acid concentration of 16.8 ± 0.23 g/l after 120 hours of fermentation. Incubation temperature at 300 C was the optimum, with citric acid concentration of 19.15 ± 0.43 g/l. Increased in agitation speed from 100 to 225 rpm gave the maximum citric acid concentration of 25.2 ± 0.32 g/l after 120 hours of fermentation. Soybean meal supplementation was the best maximum citric acid concentration of 28.2 ± 0.51 g/l. Evaluating the effect of different concentration of soybean meal shows that 0.3 % supplementation was the optimum with maximum concentration of 31.2 ±0.35g/l from cassava pulp after 120 hours of fermentation. The result suggested that citric acid can be accumulated using cassava pulp by Aspergillus niger in submerged culture during fermentation. Cassava pulp if well harnessed can be used for large scale citric acid production.

Physicochemical Properties of Mesoporous Organo-Silica Xerogels Fabricated through Organo Catalyst

The physicochemical properties of organo-silica xerogels derived from organo catalyst were pervasively investigated, including the effect of one-step catalyst (citric acid) and two-step catalyst (acid-base), and also to observe the effect of sol pH of organo-silica xerogel toward the structure and deconvolution characteristic. The organo-silica xerogels were characterized by FTIR, TGA and nitrogen sorption to obtain the physicochemical properties. The silica sol–gel method was applied to processed materials by employing TEOS (tetraethyl orthosilicate) as the main precursor. The final molar ratio of organo-silica was 1:38:x:y:5 (TEOS:ethanol: citric acid: NH3:H2O) where x is citric acid concentration (0.1–10 × 10−2 M) and y is ammonia concentration (0 to 3 × 10−3 M). FTIR spectra shows that the one-step catalyst xerogel using citric acid was handing over the higher Si-O-Si concentration as well as Si-C bonding than the dual catalyst xerogels with the presence of a base catalyst. The results exhibited that the highest relative area ratio of silanol/siloxane were 0.2972 and 0.1262 for organo catalyst loading at pH 6 and 6.5 of organo-silica sols, respectively. On the other hand, the organo-silica matrices in this work showed high surface area 546 m2 g−1 pH 6.5 (0.07 × 10−2 N citric acid) with pore size ~2.9 nm. It is concluded that the xerogels have mesoporous structures, which are effective for further application to separate NaCl in water desalination.

Obtaining and characterization films of a bioplastic obtained from passion fruit waste (Passiflora edulis)

Objective: Obtaining films from a vegetable biopolymer from the peel (a by-product) of passion fruit (Passiflora edulis) (BPM) and contribute to reduce the environmental pollution generated by the consumption of petroleum-derived plastics.Design / methodology / approach: By acid hydrolysis at four concentrations of citric acid (0, 1, 2, and 3 %), pectin was extracted of passion fruit peels, making a paste mixture with glycerol. The obtained biofilms with an approximate 1 mm thickness wereNcharacterized by transformed Fourier infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) with coupled elemental analyzer (EDS).Results: XRD diffractograms revealed that passion fruit bioplastic had a semi-crystalline structure and a calculated crystallinity index of 74.6 %. Its value reduced by the half as the citric acid increased concentration, the samples with lower concentration with greater flexibility (1 %). FTIR analysis suggested alterations in the BMP structures and adecrease of methoxyl groups in the polymeric chains with the increasing in citric acid content. Limitations/implications: SEM micrographs showed homogeneity in the films, although with some granular irregularities and folding.Findings/conclusions: The increase in citric acid concentration decreased the degree of gelation in the writing of the obtained biofilms, suggested by EDS and FTIR results, with a consequent reduced flexibility of the GMP films.

Optimization of Betalain Pigments Extraction Using Beetroot by-Products as a Valuable Source

(1) Background: This study is designed to extract the bioactive compounds from beetroot peel for future use in the food industry. (2) Methods: Spectrophotometry techniques analyzed the effect of conventional solvent extraction on betalains and polyphenolic compounds from beetroot peels. Several treatments by varying for factors (ethanol and citric acid concentration, temperature, and time) were applied to the beetroot peel samples. A Central Composite Design (CCD) has been used to investigate the effect of the extraction parameters on the extraction steps and optimize the betalains and total polyphenols extraction from beetroot. A quadratic model was suggested for all the parameters analyzed and used. (3) Results: The maximum and minimum variables investigated in the experimental plan in the coded form are citric acid concentration (0.10–1.5%), ethanol concentration (10–50%), operating temperature (20–60 °C), and extraction time (15–50 min). The experimental design revealed variation in betalain content ranging from 0.29 to 1.44 mg/g DW, and the yield of polyphenolic varied from 1.64 to 2.74 mg/g DW. The optimized conditions for the maximum recovery of betalains and phenols were citric acid concentration 1.5%, ethanol concentration 50%, temperature 52.52 °C, and extraction time 49.9 min. (4) Conclusions: Overall, it can be noted that the extraction process can be improved by adjusting operating variables in order to maximize the model responses.

Phytoextraction of Lead Using a Hedge Plant [Alternanthera bettzickiana (Regel) G. Nicholson]: Physiological and Biochemical Alterations through Bioresource Management

Phytoremediation is a cost-effective and environmentally friendly approach that can be used for the remediation of metals in polluted soil. This study used a hedge plant–calico (Alternanthera bettzickiana (Regel) G. Nicholson) to determine the role of citric acid in lead (Pb) phytoremediation by exposing it to different concentrations of Pb (0, 200, 500, and 1000 mg kg−1) as well as in a combination with citric acid concentration (0, 250, 500 µM). The analysis of variance was applied on results for significant effects of the independent variables on the dependent variables using SPSS (ver10). According to the results, maximum Pb concentration was measured in the upper parts of the plant. An increase in dry weight biomass, plant growth parameters, and photosynthetic contents was observed with the increase of Pb application (200 mg kg−1) in soil while a reduced growth was experienced at higher Pb concentration (1000 mg kg−1). The antioxidant enzymatic activities like superoxide dismutase (SOD) and peroxidase (POD) were enhanced under lower Pb concentration (200, 500 mg kg−1), whereas the reduction occurred at greater metal concentration Pb (1000 mg kg−1). There was a usual reduction in electrolyte leakage (EL) at lower Pb concentration (200, 500 mg kg−1), whereas EL increased at maximum Pb concentration (1000 mg kg−1). We concluded that this hedge plant, A. Bettzickiana, has the greater ability to remediate polluted soils aided with citric acid application.