The aims of this study were to analyze the chemical composition and to investigate the antimicrobial activity of pomelo peel oil (Citrus grandis (L.) Osbeck) extracted by steam distillation method. The antibacterial ability of essential oils was evaluated at different concentrations (50%, 25%, 10% and 5%) by agar well diffusion method with Staphylococcus aureus, Bacillus cereus, and Escherichia coli. The anti-mould acitivity of essential oils was also tested with Aspergillus flavus by agar well diffusion method. An average yield of 1.78% essential oil was achieved from pomelo peel and 25 main components in essential oil were analyzed, including terpenes, alcohols, aldehydes. The ability to inhibit 3 strains S. aureus, B. cereus and E. coli at the essential oil concentrations of 50% of the antibacterial diameter were 15.67 ± 0.76 mm, 14.0 ± 0.92 mm and 12.33 ± 0.57 mm, respectively; at 25% concentrations were 13.33 ± 0.58 mm, 11.0 ± 0.87 mm and 9.33 ± 0.58 mm. Results of resistance to A. flavus fungus by agar well diffusion method with antifungal performance at essential oil concentrations (50%, 25%, 10% and 5%) were 81.24 ± 2.25%, 62.58± 2.04%, 26.19 ± 2.02%, and 8.35 ± 2.24%, respectively.

Orange fruits contain important natural compounds with diverse biological activities. Developing new products, especially soft dried oragne, which can utilize the abundant amount of orange fruit, and provides a sustainable output for domestic production is become urgent. However, bitterness in certain orange productions is one of the major problems of the orange processing industry. Therefore, research to reduce the bitter taste in dried orange fruit need to be necessary.The objectives of the study were to determine the influence of (i) chemical type (NaOH, Na3C6H5O7, NaOH + Na3C6H5O7, NaCl and Na2CO3) and pretreatment method (soaking and blanching); (ii) concentrations of chemical (0, 50, 100, 150 and 200 ppm)  on the reduction of naringin content and remaining the nutritional value of soft dried Sanh orange. The results showed that the use of NaOH (150 ppm) as blanching solution gave the highest efficiency in reducing naringin (from 18.75 to 2.11 mg/100 g). The polyphenol and vitamin C content of sample treated with this condition remained at a high level, 5.57 mgGAE/g and 71.71 mg%, respectively.

This study was performed to isolate and identify fungi associated with two cultivars of pomelo commonly growing in the Mekong Delta, Da Xanh and Nam Roi pomelo. The results show that both cultivars of pomelo demonstrated the high frequency of fungus isolate, which was seen in a total of 8 isolates. Isolated fungi were identified morphologically, microscopically using molecular standard procedures, ITS1, and ITS4. From the peel of Da Xanh pomelo, the isolated fungal genera were Aspergillus brunneoviolaceus, A. aculeatus, A. carbonarius, Neurospora intermedia. The identification by sequencing of ITS (internal transcribed spacer) gene revealed that 8 selected isolates from Nam Roi pomelo had 98 ÷ 100% identity to A. niger, A. assiutensis, A. aculeatus,  N. intermedia, Schizophyllum commune and Penicillium sp. The identification of fungi strains presented on pomelo peel is the first step for proposing pretreatment and post-harvest technology, helping to prolong the shelf life of fresh pomelo.

The study was conducted to investigate the effects of fish status before bleeding (with and without stunning), bleeding media (water and air) and bleeding conditions (bleeding time and temperature) on the quality of snakehead fish fillets. The flesh colour, cooking yield, texture, heme iron, non-heme iron and lipid oxidation (peroxide value-PV and thiobarbituric acid-reactive substances-TBARS) were determined. The results indicated that fish fillets with stunning before bleeding had higher L* values, lower a* and b* values, and higher bleeding efficiency (lower heme iron and non-heme iron contents) compared to fish fillets without stunning. Water was a suitable medium for bleeding snakehead fish. Bleeding time and temperature were two important factors affecting the bleeding efficiency. The optimal conditions for bleeding snakehead fish were water temperature of 23-25°C for 20 minutes. 

This research is aimed to establish the processing technology of making herbal tea bags from pomelo peel of Nam Roi cultivar (Citrus grandis (L.) Osbeck). The main contents included (i) investigating the effects of pretreatment conditions (blanching, soaking in NaCl) to reduce bitter taste and maintain quality of the tea; (ii) determining tea processing conditions (pre-drying, roasting) suitable for the product; (iii) evaluating the quality of the final product by current standards. The results showed that blanching pomelo peel in boiling water (100°C) for 60 seconds helps to maintain the green color while keeping TPC, TFC, TEAC loss at the lowest. After blanching, soaking in 10% NaCl salt solution (1: 5 w/v) and then rinsing with water (1: 4, w/v) helped to remove the bitter agent and to control the bioactive ingredients of pomelo peel. Pre-drying conditions with hot air at 60°C before roasting at 140°C to final moisture of 8% helped to maintain product color and quality. The final product was safe without toxins or pesticide residues, and had the microorganisms within the maximum permissible limits.

The lime tree is a high potential crop in the Mekong River Delta. The assessment of the fruit’s quality is necessary as a basis for production and application in processing technology to add value for lime fruits. This study aimed to assess the fruit’s quality parameters of common lime cultivars in Mekong River Delta. “Chanh khong hat” (Citrus latifolia), “chanh giay” (Citrus aurantifolia) and “chanh bong tim” (Citrus limonia) were analyzed in terms of physicochemical parameters (e.g. pH value and juice color), juice percentage, total soluble solids (TSS), total titratable acidity (TTA) and sugar content. Vitamin C and citric acid were analyzed by high-performance liquid chromatography. The technological index of the fruits was also calculated and compared. The results showed that “chanh khong hat” was relatively high in TSS (8oBrix). The highest fruit percentage (40%), total sugar (2.11 g/100 mL), total vitamin C (32.5 mg/100 mL) and technological index (3.2) were found in “chanh khong hat” cultivar. The findings indicate that “chanh khong hat” would be the most potential cultivar for juice processing.

Nam Roi pomelo is a type of pomelo grown popularly in the Mekong Delta. In the process of growing pomelo, fruit can be pruned or fallen by itself at different maturity period such as 1-2 months, 3-4 months, 5-6 months until 7-8 months (nearly - ripening or ripening stage) and > 9 months is the stage when pomelo is fully ripe or overripe. The albedo of pomelo contains biological compounds with antioxidant activity. The ultrasonic-assisted extraction (UAE) and the heat-assisted extraction (HAE) were used in this study to compare polyphenol, flavonoid content and antioxidant activity of albedo at other maturity periods. The results showed that the ultrasonic-assisted extraction method had the higher efficiency in obtaining active ingredients than the heat-assisted extraction method; pomelo at the harvest age of 1-2 months had the highest content of , the second highest content followed by 3-4 months, then > 9 months, then 7-8 months and the harvest age of 5-6 months had the lowest content of bioactive substances.

The study was conducted to determine the hydrolysis conditions on the recovery of fish protein hydrolysate from snakehead fish head by using alcalase in the first stage and flavourzyme in the second stage. The research included four experiments: (i) the effects of the ratio of alcalase to material, (ii) the hydrolysis time by alcalase enzyme, (iii) the ratio of flavourzyme to material, and (iv) the hydrolysis time by flavourzyme enzyme. Fish head was hydrolyzed at 50℃, pH 8.0, and the ratio of material: ethanol 20o solution was 1:1. The results showed that fish head was hydrolyzed with 0.2% alcalase for 12 hours in the first stage and continued with 0.4% flavourzyme for 9 hours in the second stage to obtain the fish protein hydrolysate with the highest amino acid content, nitrogen recovery and degree of hydrolysis were 6.58 g/L, 44.6% and 38.0%, respectively whereas ammonia content was low at 0.269 g/L.

The Mekong Delta is one of the largest tropical fruit producing regions in Viet Nam. However, more than half of all fruits produced in this region are sold in fresh form to consumers. As a result, postharvest losses in quantity and quality of these fruits are usually substantial, especially with export fruits and those that are transported in long distance. The following review will update the factors affecting the quality of fruits with a focus on postharvest biology and technology. Important issues relevant to each specific product are discussed, such as postharvest physiology, preharvest factors affecting postharvest quality, quality maintenance postharvest, and value-added processed products.

Naringin is a flavonoid glycoside found with high levels in pomelo peels. Naringin has many good effects for human health such as antioxidant activity, cholesterol reduction, prevention of high blood pressure, etc. This study is aimed to investigate the conditions for extraction of naringin from pomelo peels. The research was carried out to select the appropriate conditions for naringin extraction including the ratio of ethanol and water (100:0, 80:20, 70:30 v/v), soaking time (0.5, 1.0, 1.5 hours), ratio of sample and solvent (1:10, 1:12, 1:14, 1:16 w/v), extraction time for immersion method (from 0,5 to 5 hours) and for Soxhlet method (from 0,5 to 7 hours). The optimal extraction conditions of naringin from Nam Roi pomelo peels were determined as followed: the ratio of ethanol and water at 80:20 v/v, the soaking time of 1.5 hours, the ratio of sample and solvent at 1:14 w/v, the extraction time of 3.5 hours for the immersion method and 5.5 hours for the Soxhlet method. The highest naringin concentrations were achieved at 0.0879 ± 0,0021 mg/mL and 3.9157 ± 0,0921 mg/mL, respectively.

The aim of study is to produce a safe antifungal polymer membrane surrounding the fruit surface which has the selective gas permeability to minimize biochemical processes and prolong the shelf life of post-harvest oranges. The antimicroorganism envelope was formed from the solution of chitosan, CMC, and silver nitrate mix into ethanol extract of physalis angulata. The fresh oranges were cleaned and dipped in the chitosan emulsion for a certain amount of time. The results showed that most of the processed samples into the preserve are fine for up to 30 days under normal conditions. The weight loss was stable, in addition, the fruit color and hardness did not change significantly, in contrast with the others. With this method, oranges can be better than usual storage, be transported to many places for a long time and are not infected with fungal diseases.

The object of this study was to obtain calcium-rich mineral powder from snakehead fish bone by alkaline enzyme, the research was carried out via the three main experiments: the bone sample was heated at 95-100  for 10 minutes before being hydrolyzed at 50  for 6 hours with the variety of enzyme concentrations (i), the influences of the drying time to the quality of mineral powder (ii), and the quality changes of calcium mineral powder occurred in 4 weeks of storage at room temperature (iii). The results showed that the hydrolyzed bone with the alkaline enzyme conccentration of 0.6% was removed 47.5% protein. After that, the sample was dried at 50  for 2 hours to obtain calcium-rich mineral powder with moisture content, solubility, recovery yield and lighteness were 10.3%; 15.1%; 70.1% and 83.6, respectively. The product of calcium-rich mineral powder from snakehead fish bone contained mineral content of 62.8% and calcium accounts for 21.01%. The product still maintained good quality, food hygiene, and food safety after being stored for 4 weeks at room temperature.

This study was aimed to identify the demands among consumers of products made from snakehead fish in the Mekong Delta of Viet Nam. A quantitative surveying of 817 consumers aged 18 to 75, in which the majority are consumers aged 25 to 35. Most consumers of this product are in the income range of 3 to 5 million VND. Current findings suggest that most respondents are willing to consume snakehead fish-derived products to diversify their daily diets due to a number of advantages. Fish paste is especially easy to prepare and could be used in a variety of dishes, hotpots and appetizers. Research showed that consumers desire to use products derived from snakehead fish to diverse family meal, fish paste were preferred because of the convenience in processing, creating many different products like hot pot, appetizer dishes. On the other hand, surveyed consumers in the Mekong Delta region had demands for products from snakehead fish such as fresh paste, dried fish, cooked fish balls/slices (fried or steamed), and even fish floss. The features that attracted consumers including a clear origin, labeling, sensory quality, natural dark color, brand name, package, quality standards applied, ingredients, and reasonable price.

The study was conducted to evaluate the quality of dried snakehead fish (Channa striata) stored at different temperatures and to compare the quality of experimental dried fish with commercial dried fish products. The results showed that low temperature limited the lipid oxidation to extend storage time, quality assurance, and food safety of dried fish products. The dried snakehead fish was still ensured about microbial standard, heavy metal, and aw after 12-week storage at room temperature (28-30°C), 32-week storage at cold temperature (0-4°C), and 48-week frozen storage (-18 to -20°C). Besides, the quality and sensory of the dried snakehead fish product in this study were higher than commercial dried fish, as well as met the standards of TCVN 5649: 2006 and TCVN 10734: 2015.

In this study, the moisture migration and solute diffusion during osmotic soaking of King mandarin in honey solution were modeled by power-law profile. Osmotic process of the product was performed until equilibrium was obtained under experimental conditions. The water loss (WL) and solid gain (SG) were computed on the basis of mass balance and the kinetic rate constants and other statistical parameters for each process were determined. Box-Behnken design was employed in order to determine the optimal processing parameters, including blanching time (30-90 seconds), honey concentration (60-80% v/v) and ratio of osmotic solution to King mandarin (1-2 times, v/w). Ascorbic acid content as well as sensory quality score at equilibrium were determined and all response data were analyzed by Statgraphics Centurion XV.I software. The optimal soaking conditions for King mandarin in honey were blanching time of 66.39 seconds, the honey concentration of 71.96% and the ratio of immersion to material of 1.57 times. The WL and SG were found to be 39,39 and 18,83 (%), respectively. The product reached equilibrium after 7 days, ascorbic acid content was found to be 9.43 mg/100 g; the sensory quality scores in terms of color and taste-flavor of product were 4.42 and 4.61, respectively.

This study is aimed to determine the physicochemical properties of Da Xanh and Nam Roi pomelos collected in the Mekong Delta region of Vietnam, thereby establishing a basis for product diversification and valorization of these two varieties. The results highlighted the difference in morphology, chemical composition, and quality characteristics of these two varieties. Da Xanh pomelo has a larger fruit size and edible pulp than Nam Roi fruit. Da Xanh pomelo's juice has the highest TSS content and the most extensive TSS /TA index, corresponding to the highest food quality. In contrast, Nam Roi pomelo contains higher levels of vitamin C, total polyphenols, and flavonoids.

The aim of the present study was to develop quality index method (QIM) and Torry shemes for assessment of freshness of vacuum-packaged snakehead fillets stored at 2-4°C. A QIM based on a total of 12 demerit points describing five sensory attributes, including colour of skin side, colour of flesh side, texture, odour, and stickness was developed. The results indicated both Quality Index (QI = 0.799*storage time + 0,6241, R2=0.9605) and Torry scores were in high correlations with storage time. Based on the Torry scores, the shelf life of snakehead fillets was 13 days that corresponded to the QI of 11. According to the results, the developed QIM scheme could be used to assess the freshness and the shelf life of snakehead fillets in combination with Torry sheme.

The present work was aimed at recovering soluble polyphenolic compounds from pomelo peel (Citrus maxima (Burn.) Merr.) of Da Xanh cultivar in different extraction and rotary evaporation conditions. To this end, the effect of raw material condition, the process of extraction, and the process of rotary evaporation (air pressure, weight loss) were examined to acquire the concentrated aqueous extract high in bioactive compounds. The analysis of data showed that by following the industrial extraction process of crushing and pressing (fresh material, with the addition of ethanol 40⁰ at the ratio of 1:1, w/v, heating to 90⁰C for 2 minutes) helped to achieve the concentrated aqueous extract with high bioactive compounds content and reduced the energy cost compared to the common approach (carried out on dried material, by immersion method with or without the assistance of microwave). Besides, rotary evaporation at the absolute pressure of 160-180 mBar was determined to be the most effective, especially in the capacity to increase the TPC, TFC, and TEAC value of the extract after solvent removal. The highest quality of concentrated aqueous extract can be obtained by rotary evaporation until 92,5% loss of weight.

Pomelo’s flavedo is rich in bioactive compounds that support health and as a source of raw materials for the food, cosmetic and pharmaceutical industries. This study is aimed to investigate effects of convection drying temperature in the range of 50-55-60-65℃ and extraction on the percentage of total phenolic contents (TPC) retention, total flavonoid content (TFC), and free-radical scavenging activity by DPPH and ABTS assays. Thereby, giving suitable drying parameters to limit the loss when heat treatment pomelo peel. The results indicate that there was a remarkable reduction (> 50%) in TPC and TFC values. Particularly, the TPC was reduced by at least 80% when the flavedo was dried 60 and 65℃ (the TPC retention was 19.21 ± 3.21% and 18.99 ± 0,87%, respectively). Temperature unfavorably affected the TFC value and led to a moderate DPPH and ABTS value. About 50% of four evaluation values were lost after the hot air convection drying.

Citrus spp. (Rutaceae) play a very important role in human food components. After harvesting, the fruits are often physiological disorders, weight loss, susceptible to fungal diseases, enable damage and reduced qualily, which greatly affects the economic value of the fruits. The diseases that occur with citrus fruits are mainly caused by pathogenic fungi on trees, including Penicillium digitatum, Penicillium italicum, Colletotrichum ssp., Lasiodiplodia ssp., Phomopsis ssp., Alternaria ssp. and Phytophthora ssp., etc. As a result, coating methods using synthetic or natural polymers are often applied to prevent the onset of pathogens. In addition to enhancing the fruit's resistance to infection, safe antifungal agents may be added to the coating of the fruit, which are approved as generally recognized as safe (GRAS) or natural edible plant extracts. In this article, the published coating methods to effective postharvest preservation of Citrus spp. fruits are categorized and presented.

Fish protein hydrolysate was performed from snakehead fish head by using flavourzyme. The research included four experiments: (i) the effects of the ratio of material: water (1:0.3; 1:0.8; 1:1.8; 1:2.8 and 1:3.8 w/v), (ii) the ratio of flavourzyme to material (0.2; 0.4; 0.6; 0.8; 1.0 and 1.2%), (iii) the hydrolysis time (12, 18, 24, 30 and 36 hours), and (iv) the hydrolysis temperature (30, 40, 50, 60 and 70oC) on the quality of fish protein hydrolysate. The results showed that fish protein hydrolysate had the highest amino acid content, nitrogen recovery and degree of hydrolysis were 6.49 g/L, 42.5% and 39.1%, respectively whereas ammonia content was the lowest at 0.205 g/L when fish head was hydrolysed at the ratio of material: water of 1:0.8 and the ratio of flavourzyme to material of 0.6% for 30 hours at 50oC.

The research was aimed to evaluate the production process and analyze the quality of commercial dried snakehead fish. The two investigated production areas are Cho Moi district, An Giang province and Tam Nong district, Dong Thap province. The finding reveals that dried fish and fish floss are the two most common products from snakehead fish, with 28 households producing dried fish and 06 households producing fish floss and all of these households have been making stable incomes. Both products processed according to traditional methods, the processing formula based on experience, equipment/machinery is not synchronized. The dried fish production scale is larger and more common when compared with the fish floss. The analytical results showed that all five commercial dried fish samples had higher microbiological parameters than the permitted level. The water activity was all higher than 0.75 - the lowest value is according to TCVN 10734: 2015. For snakehead fish floss, the products' quality and safety meet the requirements, but the phosphate content (% P2O5) has the value 0.62-0.78% - higher than the permitted level (0.5%).