Physicochemical properties and oxidative storage stability of milled roselle (Hibiscus sabdariffa L.) seeds

Milled Roselle (Hibiscus sabdariffa L.) seeds of the UMKL cultivar were analyzed for proximate composition, water and oil absorption capacity, and the influence of storage conditions on storage stability. The storage stability was determined under four types of conditions: light/oxygen (air) (LO), light/nitrogen (LN), darkness/oxygen (air) (DO), and darkness/nitrogen (DN) while monitoring for seven consecutive months. During the storage period, the formation of volatiles was determined using dynamic headspace sampling and Gas Chromatography-Mass Spectrometry (GC-MS) analysis. In total, 85 volatiles were identified, mainly aldehydes, alcohols, ketones, furans, and acids indicating lipid oxidation. It is recommended that milled Roselle seeds should be flushed with nitrogen and stored in darkness. Under these conditions, the seeds can be stored for at least three months without changes in volatile profile. This is important to ensure the good quality of milled Roselle seeds for further commercialization

The influence of internship determinants on hospitality undergraduates’ satisfaction level: A case of public universities in Malaysia / Syafinaz Ruslan … [et al.]

Being a university undergraduate no longer guarantees job placement. Previous literature has proven that the work experiences of an internship program make a significant impact on students' career choices as it provides students with realistic expectations of their future careers. Students who have undergone their internship program agree that internship satisfaction would have a strong influence on their career intentions. Although several studies emphasized on student internship experiences and career intention, there is a lack of empirical research that has been carried out on the relationship between internship determinants and internship satisfaction, particularly within the hospitality context. Therefore, this present study aims to examine the factors associated with internship satisfaction. There are three factors identified as the determinants of the internship satisfaction, namely job characteristics, organizational environment, and contextual factors. A quantitative research method involving 302 hospitality undergraduates from seven public universities that offer Bachelor in Hospitality and Food Service courses in Malaysia had been conducted. Findings from the three independent variables (job characteristics, organizational environment, and contextual factors) show that the organizational environment has the highest impact on internship satisfaction (beta = .480), followed by job characteristics (beta = .366), and contextual factors (beta = .113)

Optimization of hot-air drying conditions on the physicochemical characteristics of torch ginger (Etlingera elatior).

Response surface methodology (RSM) was used to determine the effect of hot-air drying on physicochemical characteristics of torch ginger (Etlingera elatior). Three independent variables were time (3-5 hours), temperature (40-80°C) and loading capacity (0.5-2 kg/m 2). In this research, 20 treatments were assigned based on central composite design (CCD) containing 8 factorial points, 6 centre points and 6 axial points. The quality of dried Torch ginger produced was evaluated by determining moisture content, water activity, Hunter L, a, b values and texture (brittleness). The results revealed that the linear terms exhibited significant (P0.05) lack of fit was indicated for the reduced models, except for the models fitted for texture. The optimization results indicated that the best response, within the range studied, was reached when the drying time was 4.1 h, the drying temperature 79°C and loading capacity 0.7kg/m 2, respectively. No significant (p>0.05) difference was found between the experimental and predicted values, thus ensuring the adequacy of the response surface models employed for describing the effects of hot-air drying on physicochemical properties of Torch ginger

High-performance liquid chromatography (HPLC) analysis for flavonoids profiling of Napier grass herbal tea

Natural plant products are becoming more and more essential in helping to promote safe well-being worldwide. This leads to a substantial rise in the consumption of various herbal teas. The presence of beneficial bioactive ingredients such as flavonoids may be correlated with Napier grass herbal tea having health benefits associated with their intake. Studies have shown that herbal teas have preferentially high antioxidant activity due to the presence of flavonoids in them. The purpose of this study was to identify the Napier grass herbal teas flavonoids prepared under different conditions. Napier grass herbal teas have been formulated using green tea and black tea processes, respectively. The tea samples were extracted in water (95°C, 30 mins) and 60% (v/v) aqueous methanol (30 mins), respectively. Approximately, 1% (v/v) aqueous acetic acid solution (solvent A) and acetonitrile (solvent B) were used as the mobile phase. The flow rate was adjusted to 0.7 mL/min, the column was thermostatically controlled at 28°C, and the injection column was kept at 20 μL. HPLC chromatograms were detected using a photodiode array UV detector at 272 nm. Gallic acid, P-coumaric acid, catechin, epigallocatechin gallate, quercetin, rutin, myricetin and kaempferol were found in both Napier grass water and methanolic extracts, respectively. The findings suggested that the HPLC techniques are ideal for the detection and identification of flavonoids in Napier grass teas

Influence of pectinase–assisted extraction time on the antioxidant capacity of Spent Coffee Ground (SCG)

Spent Coffee Ground (SCG) comprises a range of functional components with high antioxidant potential and health benefits. Although SCG has many advantages, antioxidant values obtained using enzymes is still scarce. Several studies reported that the use of enzyme-assisted extraction techniques could improve the detection of antioxidant compounds in samples of by-products. In this study, SCG was extracted using enzymeassisted techniques for different periods (0, 20, 40, 60, 80 and 100 mins). The total antioxidant capacity was measured using Peroxidase, Catalase, Ferric reducing antioxidant power (FRAP), Superoxide radical scavenging assay (SRSA) and 2,2-diphenyl-2- picrylhydrazyl (DPPH) analysis. 60 mins extraction was found to exhibit antioxidant activity in DPPH, SRSA, Catalase and Peroxidase of 84.18±7.01%, 32.83±6.75%, 76.65±5.52% and 75.01±7.67%, respectively. Besides that, the extraction also gave a high amount of content with 267.17±26.69 mg TAE/mL and 58.30±2.36 mg QE/g in total phenolic content and total flavonoid content respectively. Flavonoids such as quercetin, kaempferol, rutin, gallic acid, catechin, epigallocatechin, p-Coumaric acid and myricetin were found to be present in SCG extract. A high amount of catechin was found in all periods of extraction, whereby 60 mins had the highest concentration of 1741.65 mg/L, while 40 mins had the lowest concentration which was 389.85 mg/L. In conclusion, 60 mins extraction using a pectinase-assisted method was the best extraction period. Additionally, the individual flavonoid catechin in SCG showed that it has potential as an antioxidant. Finally, there is a strong correlation between antioxidative activity and both phenolic and flavonoid content

Effects of hot-air drying on physicochemical characteristics, flavour profiles and sensory acceptance of Citrus hystrix and Etlingera elatior jack

Herbs and spices play important roles in Malay cuisine. The usage of kaffir lime (C. hystrix)leaves and torch ginger (E. elatior) are not only limited to the addition of flavour and enhancement of palatability of food but they also act as antioxidants. Both herbs were grown for both flavouring and medicinal purposes. However, this herb is highly perishable in nature, have short shelf life and deteriorate rapidly after harvesting that leads to loss of flavour and quality. So, drying is an important technology for preserving the product quality and also preventing the spoilage of the product during storage. Thus, this study was conducted to optimize the effects of hot-air drying conditions (drying time, drying temperature and loading capacity) on physicochemical characteristics (moisture content, water activity, texture and colour) of C. hystrix and E. elatior that could be used for a high food grade spicing material. Secondly, the flavour profiles of C. hystrix and E. elatior were determined between fresh and optimally dried herbs. The herbs inclusion/infusion parameters levels (size, temperature and concentration of herbs) on sensory acceptance of Vichyssoise soup and sorbet were also optimized. The results showed that the best response for torch ginger, within the range studied, was reached when the drying time was 4.1 h, the drying temperature, 79 °C and loading capacity, 0.7 kg/m2 respectively. On the other hand, the overall optimum conditions that resulted in desirable dried kaffir lime leaves, was achieved when the drying time was 4.9 h, the drying temperature, 60 °C and loading capacity, 1.4 kg/m2. No significant (p>0.05) difference was found between the experimental and predicted values, thus ensuring the adequacy of the response surface models employed for describing the effects of hot-air drying on physicochemical properties of torch ginger and kaffir lime leaves. At the second stage, liquid-liquid solvent extraction was employed to extract flavour compounds of the samples which were analyzed using Gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC-MS) with DB-5, BPX-5 as well as Quadrex007CW columns. The finding from GC and GC-MS revealed that fresh torch ginger contained 91 volatile compounds while optimally dried torch ginger contained 104 volatile compounds using Quadrex007CW column. However, only 54 volatile compounds of fresh torch ginger and 147 volatile compounds of optimally dried torch ginger were obtained using DB-5 column. The major aroma components in both fresh and optimally dried torch ginger were alcohol, ester, alkane, carboxylic acid, ketone and aldehyde. A total of 45 compounds were identified in fresh kaffir lime leaves as compared to 41 compounds in optimally dried kaffir lime leaves using BPX-5 column. However, a total of 66 compounds were determined in fresh kaffir lime leaves and 40 compounds in optimally dried kaffir lime leaves using DB-5 column. Monoterpenes and sesquiterpenes were found to be major components. Finally, the herbs inclusion/infusion parameters levels [size of herbs (2-100 mm), concentration of herbs (3-15 g/L)and temperature of inclusion (25-100 °C)] in different types of food systems (liquid and semi solid) were determined. Sensory evaluations using 50 untrained panelists were utilized to assess colour, aroma, taste and overall acceptability of products. The results from sensory valuation showed that vichyssoise soup flavoured with optimally dried C. hystrix leaves were more highly preferred by panelist compared to vichyssoise soup flavoured with optimally dried E. elatior while sorbet flavoured with optimally dried C. hystrix were highly preferred by panelist compared to sorbet flavoured with optimally dried E.elatior. This study has significantly contributed to the establishment of standardized measurements for the amount of herbs required for various kinds of foods. Potentially, this study also yields herbs that reaches international specification standard and enables worldwide export of Malaysian herbs

Headspace solid-phase microextraction analysis of the volatile flavour compounds of roasted chickpea (Cicer arienum L).

Headspace-solid phase microextraction coupled with gas chromatography-mass spectrometry analysis were used to provide the volatile profile of roasted chickpea as a means of unravelling and elucidating roasted chickpea as a prerequisite in developing chickpea snack item for the health and functional food sectors. The results of the HSSPME and optimization analysis using response surface methodology showed that DVB/CAR/PDMS was the most effective fibre and further results revealed the extraction temperature to be the dominant factor. A total of 61 volatile compounds were identified in the roasted chickpea. The best response within the range studied was established at 60oC extraction temperature, 30 min of equilibrium time and 15 min of extraction time. The volatile compounds identified comprised of aldehydes (25%), hydrocarbons (25%), terpenoids (20%), esters (8%), ketones (8%), alcohols (8%) and heterocyclic (8%). The results further indicated that the final model was significantly (P < 0.05) fitted for the response variable (total flavour peak area) studied with a relatively high R 2(0.9658)

Changes in physicochemical properties and volatile compounds of roselle (Hibiscus sabdariffa l.) calyx during different drying methods

Fresh roselle are high in moisture and deteriorate easily, which makes drying important for extending shelf-life and increasing availability. This study investigated the influence of different drying methods (oven-drying, freeze-drying, vacuum-drying, and sun-drying) on the quality of roselle calyx expressed as physicochemical properties (moisture content, water activity, soluble solids, color), volatile compounds, and microstructure. Oven-drying and freeze-drying reduced moisture content most while vacuum-drying and sun-drying were not as efficient. All drying methods except sun-drying resulted in water activities low enough to ensure safety and quality. Vacuum-drying had no impact on color of the dry calyx and only small impact on color of water extract of calyx. Drying reduced terpenes, aldehydes, and esters but increased furans. This is expected to reduce fruity, floral, spicy, and green odors and increase caramel-like aroma. Sun-drying produced more ketones, alcohols, and esters. Scanning electron microscopy revealed that freeze-drying preserved the cell structure better, and freeze-dried samples resembled fresh samples most compared to other drying techniques. The study concludes that freeze-drying should be considered as a suitable drying method, especially with respect to preservation of structure