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Avocado contains a variety of essential nutrients and important phytochemicals. At present, the drying method is widely used to increase the commercial life and availability of avocado pulp. In this study, the drying characteristics of avocado pulp by freeze drying (FD) and superheated steam drying (SHD) methods were evaluated. The SHD process occurred faster than FD, respectively, by 4 and 15 h. The loss of polyphenols and antioxidant activity of avocado flesh on drying process was relatively high, depending on the drying method and temperature. SHD has a lot of superiority that is a suitable drying method for avocado pulp. The empirical data on avocado pulp drying were used to build mathematical models that simulate moisture ratios against operating times. The statistical values revealed that the Wang and Singh model and the Page model were appropriate to depict dehydration behaviour for avocado pulp by FD, whereas the Page and Modified Page models were appropriate for the SHD method.

Nylon 66, which is an important membrane class used in manufacturing of chitin and chitosan, have a number of features that can be improved by surface functionalizations into a novel composite structure with support of ultrasound and silica gel (SiG) catalyst in a doubled amidation reaction. Firstly, nylon 66/para-phenylenediamine thin film composite (NP-TFC) is prepared from commercial nylon 66 membrane in an ultrasound assisted hydrolysis-amidation reaction. Secondly, carboxylic functionalized multi-walled carbon nanotubes (MWCNT-COOH) are grafted on the NP fiber in an ultrasound assisted/SiG-catalyzed amidation reaction, where para-phenylenediamine (pPD) role is cross-linking. As an excellent result confirmed by either Fourier transform infrared (FTIR), Raman spectrometry or scanning electron microscopic (SEM), bundled MWCNTs bridges are easily built in SiG-catalyzed ethanol media to connect nylon 66 fibers at distances of 0.3–1 μm. The vacuum filtration test confirmed that as-prepared nylon 66/pPD/MWCNTs structure has superior Ca2+ rejection efficiency to that of original nylon 66.

Gamma- Aminobutyric Acid (GABA) has been known as a bioactive related to the hyperglycemia, boosting the immune system, lowering blood pressure, inhabitation of development of cancer cells and assists the treatment of anxiety disorders. It has been supplied for human from germinated beans, cereal grains and tea. Recently, GABA has been also synthesized from the fermentation through the assimilation of glutamic acid by bacteria. In this paper, application of ultrafiltration (UF) for recovery of GABA from the fermentation broth of rice bran extract was investigated, with 1,000 Da of molecular weight cut off of membrane. Pretreatment of the broth by combination of centrifugation and microfiltration prior to UF improved the performance of UF process. Influence of operating pressure, in range of 2 -10 bar, was investigated and 6 bar was suitable value of operating pressure for UF of the fermentation broth. The mechanism of fouling in UF under influence of methods of pretreatment and operating pressure was also analysed, consequently, determined the flux decline model in UF. Compared to feed, content of protein in broth reduced 65 %, while, content of GABA was insignificantly changed, at 2.5 of concentration factor. Content of soluble solid, sugar and amino acid in the broth also reduced after UF process. It means that, UF process is potential technology for recovery of GABA from fermentation broth of rice bran extract.

Crude rice bran oil (CRBO) contains high levels of oryzanol, a bioactive shows many significant benefits for human health. The content of oryzanol in CRBO is relatively low for recovery by solvent extraction. Tthe refinery by chemical process also causes to lose a significant amount of oryzanol. Dense membranes can be applied for treatment of CRBO to refine the oil. The limitation of dense membranes is high resistant to permeate flux, consequently, very low capacity. In this research, the porous composite membrane was applied for enrichment of oryzanol, simultaneously, refinery of CRBO. The influences of temperature, pressure and adding of organic solvent (ethanol and n-hexane) on the separation of oryzanol, phospholipids (PL) and wax were conducted. Results show that, increase in temperature led to increase in oryzanol rejection. On the other hand, increase in operating pressure and adding of organic solvent caused decrease in oryzanol rejection. Under the operating conditions as the following: polypropylene membrane (HR98PP), ambient temperature, 50 bar and adding n-hexane with 4: 1 (w:w) of solvent: CRBO, at 1.73 of the concentration factor; the content of oryzanol in accumulative permeate was 1.8 g/L, consequently, increased 1.41 fold compared to the feed. More than 97 % of PL and wax were rejected from the feed. It means that, treatment of RBO by composite membrane is the potential technique for not only enrichment of oryzanol, but also refinery of CRBO.

Pineapple has been known as one of the most popular tropical fruits in Vietnam with a production of over 674,000 t in 2018. However, by-products from pineapple cultivation account for approximately 65 % of the fresh fruit weight and are mostly being dumped, decomposed or burnt now. Therefore, it has recently raised great concern about environmental pollution. For the first time, extracted fibres from pineapple leaves being utilized for developing successfully eco-friendly and cost-effective pineapple fibres (PFs) aerogels by using polyvinyl alcohol as a cross-linker and following a freeze-drying method. The morphology of the PFs aerogels can be controlled well by changing the PFs concentration (0.5 - 2.0 wt%). The PFs aerogels exhibit extremely low densities (12.7 - 32.6 kg/m3) and high porosities (96.9 - 98.8 %). The BET result shows that the surface area of the PFs aerogel has up to 5.6 m2/g and their pore size of 1.3 - 2.2 nm. The developed PFs aerogels show extremely low thermal conductivities ranging from 0.030 to 0.034 W/m.K. Due to the low Young’s modulus values ranging from 0.47 - 7.86 kPa, the PFs aerogels are flexible and can be used for heat insulation of the buildings as well as food preservation.

The influence of an alternating current (AC) frequency from 50 to 20,000 Hz at 30 V/cm using ohmic heating on the inactivation of E. coli O157:H7 in buffer peptone water (BPW) and pomelo juice was investigated. Frequency affected bacterial reduction in both BPW and pomelo juice with the same trend, and the most efficient reductions were obtained at 60 and = 500 Hz. Besides, the resistance of E.coli O157:H7 was investigated. BPW and pomelo juice were treated at different temperatures (62-71 C) for various times (0-30 s) by ohmic heating (OH) and compared with conventional heating (CH). The technical parameters of OH were an electric field strength of 30 V/cm and frequencies of 60 and 500 Hz. At each temperature, the decimal reduction time (D) and the decimal reduction temperature (z) were determined. Microorganism reduction was significantly higher (P < 0.05) with OH than with CH, and there was no significant difference between the juice samples treated by OH at 60 and 500 Hz. For OH at 60 Hz, the D values of E. coli O157:H7 in pomelo juice were 59.0, 27.3, 10.3, and 3.6 s at temperatures of 60, 62, 65, and 68 C, with a z value of 6.7 C. For CH, the D values were 35.4, 14.3, 8.2, and 2.9 s, with a z value of 8.6 C. From the calculated D and z values, a processing schedule for the pasteurization of pomelo juice can be estimated. Observing the bacterial cells by transmission electron microscopy (TEM) showed considerable changes in the morphology of the bacterial cells with OH, which might be the cause of cell death. These results demonstrated that the electric field obtained with OH yields additional microbial destruction. As a result, the time and temperature required for bacterial inactivation can be reduced, diminishing the negative heat effects of pasteurization on the food products.

The paper focused on the influence of operative conditions on the separation of benzoic acid from 10 °Brix cranberry juice by cross-flow nanofiltration with a plate and frame pilot scale (DDS Lab Module Type 20 system). Six kinds of commercial nanofiltration membrane were investigated. The results showed that the rejection of benzoic acid was significantly lower than that of other components in cranberry juice, including sugars and other organic acids. In a range of 2–7.5 L/min, feed flow rate slightly affected the performance of nanofiltration. Higher temperatures resulted in higher permeate flux and lower rejection of benzoic acid, whereas rejection of sugar and organic acid was stable at a high value. In a range of 2.5–5.5, pH also significantly affected the separation of benzoic acid and negative rejection against benzoic acid was observed at pH 4.5 with some of the membranes. This implies that pH 4.5 is considered as an optimum pH for benzoic acid separation from cranberry juice. The lower permeate flux caused a lower rejection of benzoic acid and negative rejection of benzoic acid was observed at the low permeate flux. Pretreatment by ultrafiltration with CR61PP membranes could improve the permeate flux but insignificantly influenced the efficiency of separation. The results also indicated that NF99 and DK membranes can be effectively used to separate benzoic acid from cranberry juice.