Mango purée is a byproduct of the current production processes (such as freeze-drying, dehydration) after the product shaping stage or grades II and III mangoes. Currently, fruit bar is a convenient and highly nutritious snack made from fruit. The objective of this study is to utilize mango byproduct in order to develop a fruit bar processing technology, which is based on evaluating the quality (color, break force, vitamin C content, and sensory) when varying the pH of mango purée and the concentration of added pectin. Additionally, total soluble solids (TSS) after blending at 80°C were also investigated. The increase in pH, pectin concentration of mango purée, and TSS after blending showed that vitamin C content in fruit bars tended to decrease. TSS results revealed that at °Bx, pH 3.3, and a pectin concentration of 1.3%, the product received a high rating of 6.3. Additionally, the vitamin C content of the product reached 7.82 mg/100 gDW. The results of this study are expected on the diversification of products from mango. Solving the situation that grades II and III mangoes are difficult to be commercialized and making the most of the byproduct mango flesh after certain production processes.

The isolation of acid-soluble collagen (ASC) from by-products of snakehead fish (Channa striata), including skin and the mixture of skin and scale, has been investigated. The recovery yield of fish skin ASC (13.6%) was higher than ASC from fish skin and scale (12.09%). Both ASCs were identified as type I collagen and showed maximal solubility at pH 2. Collagen samples from the mixture of skin and scale had higher imino acid content (226 residues/1000 residues) and lower wavenumber in the amide I and amide III region (1642 and 1203 cm⁻¹, respectively) than the fish skin ASC (the imino acid content was 220 residues/1000 residues and the wavenumber in the amide I and amide III were 1663 and 1206 cm⁻¹, respectively. The difference scanning calorimeter (DSC) showed higher thermal stability in ASC from the mixture of skin and scale (T_d of 35.78 °C) than fish skin ASC (34.21 °C). From the result, the denaturation temperature of ASC had a close relationship with the content of imino acid as well as with the degradation of α-helix in amide I and III. These results suggest that collagen could be obtained effectively from snakehead fish by-products and has potential as a realistic alternative to mammalian collagens.

Pomelo (Citrus maxima (Burm. f.) Merr). juice is known as an enriched source of antioxidants and nutrients. It is therefore necessary to develop a preservation method for freshly prepared juice. This study aims to determine the effect of the vacuum concentration process on the change in color, bioactive compounds and antioxidant activity of pomelo juice. High pressure showed negligible effects on color. However, longer heating time seemed to cause browning in juice. In comparison with the fresh sample, total color difference (TCD) value of the treated sample was 6.73 ± 0.58 after 150 min of heating at 85°C. The total polyphenol content (TPC) values in the sample also increased with longer heating time or increased pressure. The total flavonoid content (TFC) seemed to be non-responsive to changes in heating time and pressure but was closely related to total soluble solid. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) of pomelo juice are affected by heat and, to a lesser extent, by pressure. The changes caused by the application of vacuum dehydration in the juice texture resulted in a higher water loss and higher sugar content (52.92 ± 0.79 °Brix).

This study aimed to identify phytochemicals and evaluate antioxidant activities of different extracts from Eucalyptus camaldulensis, an aromatic plant in the Myrtaceace family. Examined extracts in different solvents such as diethyl ether extract (DEE), the ethanolic extract (EE) and the aqueous extract (AE). Total polyphenol and total flavonoid contents were determined via aluminum chloride colorimetric method. Antioxidant activity was performed via ABTS and DPPH radical scavenging assays. The results showed that a wide variety of pharmacologically active compounds such as alkaloid, oil, flavonoid, triterpenoid, saponin, tannin and polyphenol were present in the leaves of Eucalyptus camaldulensis. The result of quantitative determination showed that total polyphenol content of the diethyl ether extract, ethanolic extract and aqueous extract achieved 73.47 ± 1.64, 306.48 ± 3.87 and 76.47 ± 1.64 mgGAE/g, respectively. Meanwhile, total flavonoid content was 41.74 ± 2.21, 45.98 ± 1.79 and 18.05 ± 0.81 mgQE/g, respectively. The ethanolic extract exhibited the highest DPPH (IC50 = 10.52 ± 0.14 μg/mL) and ABTS (IC50 = 9.86 ± 0.17 μg/mL). These results indicate that Eucalyptus camaldulensis leaves can be used in dietary applications with the potential to reduce oxidative stress.

This study attempted the optimization of the extraction process involving essential oils from Vietnamese pomelo fruits. Three influential parameters including ratio of water and material, extraction time, and temperature were assumed to be impactful to the oil yield and were investigated by establishing a statistical model. A central composite design was adopted to generate dataset required for estimation of the model. Analysis of variance was used to calculate model significance. The results showed that optimum yield of pomelo oil is 4.46 % (v/w) corresponding to water ratio of 507 mL water to 100 g sample, temperature at 119.29 ºC and distillation time of 113.68 min. Predicted values proposed by the Design Expert 11 software well-agreed with the empirical data, suggesting the excellent predictability of the proposed models. In addition, the essential oil obtained under optimal conditions was analyzed by gas chromatography-mass spectrometry. The results indicated that D-limonene is the main component (97.318 %) of essential oil.

The lemongrass (Cymbopogon citratus L.) essential oil plays a vital role as an ingredient in different fields due to aromatic, antibacterial properties and antifungal activity. In this study, essential oil of lemongrass was obtained using hydrodistillation method and evaluated for chemical compositions and physico-chemical characteristics. The averaged physico-chemical parameters were determined as specific gravity (0.8865 g/cm3), acid index (2.948), ester index (6.402) and refractive index (9.35). Moreover, the hydrodistillation process performance was achieved 0.29%. The composition of essential oils was analyzed by GC-MS, revealing a total of 18 volatile constituents existing in the lemongrass oil. The major components were α-citral (40.838%), β-citral (28.494%), β-myrcene (16.654%), 2,3-dehydro-1,8-cineole (2.264%) and geraniol (2.388%). The citral component accounts for high content (more than 70% of volume) of oil.