Thin Layer Drying Characteristic of Morinda Citrifolia Fruit and Drying Effects on 6 – Methoxy-7-Hydoxy-Coumarin Content

This study presents the thin layer drying characteristic of Morinda Citrifolia Linn fruit and drying effects on scopoletin content. The optimum mature stage of M.citrifolia fruit was found to be four months after bud flowering with high scopoletin content of 1.65'gSC/g fresh weight. Thin-layer drying characteristics of M. citrifolia fruit slices were investigated at 50, 60 and 70oC, and air velocity of 0.5, 1.5 and 2.5 m/s. Relative humidity range of 64-85 % was observed. The drying time required to reduce the moisture content from initial average value of 5.25g water/g dry solid (= 84%wet basis ) to a desired final moisture of less than 0.053g water/g dry solid (=5%wet basis) was 6.0h, 3.0h and 1.5h for drying air temperatures of 50oC, 60oC and 70oC respectively. An increase in drying temperatures shortened the drying time. The drying time needed to dry M. citrifolia fruit slices at intermediate moisture content decreased when the air velocities was increased at constant drying temperature. However, different air velocity had no significant difference in overall drying time to achieve equilibrium moisture content at constant temperature. Drying rates for M. citrifolia fruit as affected by drying air temperature and air velocity were determined. The influence of temperature on the drying rate is more pronounced as compared to the influence of the air velocity. From the drying rates it was observed that drying of M. citrifolia fruit slices took place under the falling rate period. The drying data were then fitted to different semi-theoretical models such as diffusion, Lewis and Page models, based on the moisture ratio (MR). The results of analysis showed that Page model gave better predictions than other models, and satisfactorily described the thin-layer drying characteristics of sliced M. citrifolia fruit. Freeze drying and hot air drying experiments were conducted on M.citrifolia fruit. The effect of drying on scopoletin content of M.citrifolia was evaluated. Spectrofluorometer was used for the determination of scopoletin in M.citrifolia fruit. An analysis of variance (ANOVA) revealed that there is no significant difference in scopoletin content obtained from freeze dried and hot air dried sample. This study shows that the remaining scopoletin content after either drying technique is nearly 26% of the initial conten

Effect of amylose content on estimated kinetic parameters for a starch viscosity model.

The apparent viscosity profile of starches during gelatinization varies with different amylose content. This study focused on the influence of amylose content on the kinetic parameters of a starch viscosity model for corn starches. The five parameters were: gelatinization rate constant (kg), gelatinization activation energy (Eg), relative increase in apparent viscosity during gelatinization (Aα), relative decrease in apparent viscosity during shearing (B), and viscous activation energy (Ev). The parameters were estimated at different amylose content using both ordinary least squares nonlinear regression and the sequential method. The mixer viscometry approach was used to measure apparent viscosity. The first part of this paper presents parameter estimation results for waxy corn starch. The model was validated by using the parameters to predict viscosity for the same starch in a different measuring system, i.e., the RVA. The second part of this paper presents the estimated parameters for corn starch blends at different amylose content. The following parameters were significantly affected by amylose content: kg and Eg both decreased with amylose content by an power-law relationship. Activation energy of gelatinization ranged from 121 to 1169 kJ/mol. The other parameters Aα, B, and Ev were not significantly influenced by amylose content. In summary, the gelatinization parameters kg and Eg dramatically decreased as amylose increased from 3% to 35% (waxy corn starch blends)

Development of beetroot (Beta vulgaris) powder using foam mat drying

Beetroot (Beta vulgaris) is normally used as natural food colorants in food industry. The objectives of this research are (1) to determine the effect of types (egg albumen and fish gelatine) and different concentrations of foaming agents on foam properties of foam mat drying beetroot, (2) to evaluate the physicochemical properties (color, pH, Brix, bulk density, water activity, hygroscopicity and moisture content) of foam dried beetroot powder, and (3) to determine the effect of temperature on rehydration ratio and color changes of rehydrated foam mat dried beetroot powder. Beetroot foam was spread at 3 mm thickness and hot air dried at 50 °C for 6 h in cabinet dryer. Beetroot pulp can be successfully foamed using egg albumen and fish gelatine as foaming agents, further hot air dried and grinded into powder. In this experiment, beetroot powder after foam mat drying was considered as hygroscopic food and resulted in lighter and reddish in colour. After rehydrating foam mat dried beetroot powder, L* value decreased but a* and b* values increased. Generally, sample beetroot with fish gelatine (BFG) had good foam expansion, foam density, hygroscopicity, water activity, and red color's powder

Rheological properties of native and modified corn starches in the presence of hydrocolloids

Starch and hydrocolloids were often used together in food industry to modify the rheological properties with the aim to enhance the starch tolerance to processing conditions. As such, the rheological properties of xanthan gum (XG), carrageenan, high (HMP) and low methoxyl pectin (LMP), with native corn starch (NCS) and modified corn starch (MCS) at different temperature were evaluated in this study. The flow behavior index (n) of corn starch-hydrocolloid mixtures were observed in the range from 0.160 to 0.604 where indicated the shear thinning behavior. The addition of hydrocolloids increased the apparent viscosity of the starch system. NCS mixtures showed consistency index (K) and apparent viscosities (na,100) decreased with increase in the temperature. The addition of XG and carrageenan increased the storage (G’) and loss (G”) moduli. Among the hydrocolloids, the XG addition to the NCS exhibited superior viscoelastic properties as evidenced by the highest G’ and lowest tan δ values. XG was observed capable to increase while pectin reduced the solid-like starch system. This result provides pragmatic data for food engineer in process design and food product development by minimizing the cost of trial and error

Color and rehydration characteristics of natural red colorant of foam mat dried Hibiscus sabdariffa L. powder

This research was aimed to develop natural red colorant powder from Hibiscus sabdariffa L. fruit using foam mat drying. Egg albumen (EA) at different concentrations (5–20% w/w) was used as a foaming agent, and samples were whipped for 10 minutes. The samples were hot air dried at 50°C for 6 hours. Effect of EA concentration on the foam properties and physicochemical properties of the powders were analyzed. In addition, the effect of temperatures (10–80°C) on color and rehydration characteristics of rehydrated powders were studied. The result showed that 15% EA concentration of foam mat dried H. sabdariffa L. powder has good quality characteristics

Extraction and quantification of saponins: a review

Saponins, a second metabolites mainly derived from plant materials, have been used extensively in drug-related industry due to the pharmaceutical properties. These have driven the emergence of various new extraction technologies with the main purpose to optimize the yield in order to accommodate the recent need. The plants containing saponins are discussed, and their pharmaceutical properties and applications in food are highlighted. This review focuses on the saponin extraction with emphasis on conventional and green technology techniques employed in previous works by relating to their specific objective in each study. The quantification methods of saponins yield, i.e., spectrophotometric and chromatographic, are summarized and discussed. In addition, this review aims to provide a point of reference to researchers who wish to design experiment to suit their particular objective in swift

Effect of dried and extrudate of bitter gourd fruit on epithelial microflora in raw chicken legs meat

Plants have been used recently to eliminate bacterial growth in food products. This study was undertaken to test the in vitro sanitizing effect of crude extract from bitter gourd (BG) fruit on the growth of native microorganisms in raw chicken leg meat. Hot air dried BG and extrudate extracts at 1% concentration and exposure times of (5, 10 and 15 min) were used to treat the samples using dilution method. Results showed that BG extrudate had a slightly stronger bactericidal activity against the microflora than the B.G. hot air drying treatment, especially, on E. coli at all exposure time. Overall, there is no significant difference between the treatments; Total Plate Count (TPC), Escherichia coli, Bacillus cereus, Staphylococcus aureus. The best reduction time of microflora by hot air dried extract was at (15 min) except for B. cereus was at (5 min) and for extrudate extract was at (5 min) except for E. coli was at (10 min). In conclusion, bitter gourd extract could be used as an important natural sanitizer for rinsing raw food matrials such chicken meat

Comparison between conventional and alternative peeling methods on peeling efficiencies of Malaysian 'Chok Anan' mango (Mangifera indica L.) fruit

Fruit industries require convenient peeling method, especially during puree processing to prevent deterioration of fruit quality and product loss. Therefore, manual, chemical (sodium hydroxide/NaOH) and enzymatic (Pectinex Ultra SP-L) peeling methods were compared to determine the peeling efficiencies of ‘Chok Anan’ mangoes. The effect of different peeling parameters (concentrations [chemical peeling: 1.6-7.3% of 0.4M-1.83M; enzymatic peeling: 0.005-0.095%], temperatures [chemical peeling: 80-95°C; enzymatic peeling: 25-40°C], and duration of soaking [chemical peeling: 5-10 min; enzymatic peeling: 30-120 min]) were evaluated for peeling yield, peeling time, absorption of chemical and enzyme solution, the penetration depth of NaOH and enzyme activities (reducing sugar analysis). The enzymatic peeling had significantly (p0.05) in peeling yield (>86%), but there was significant (p<0.05) effect on absorption of both NaoH and pectinase solutions at 0.84g/100g (enzymatic) and 2.50g/100 g (chemical), 0.45 mm penetration depth of NaOH and significant decrease in enzyme activities from 20.04g/100 mL to 4.92g/100 mL using reducing sugar analysis. The optimal enzymatic peeling conditions (concentration: 0.009%, temperature: 25°C, duration of soaking: 120 min) had made it possible to recycle the pectinase solution twice thus may be beneficial for the mango processing industry compared to chemical peeling

Effect of extrusion barrel temperatures on residence time and physical properties of various flour extrudates

The aim of this study was to evaluate the effect of barrel temperature and flour types on the residence time and physical properties of various flour extrudates. Corn flour, rice flour, corn flour with potato starch (30% w/w, d.b), and rice flour with potato starch (30%w/w, d.b) were extruded at screw speed of 75rpm, feed moisture at 25% (w/w, w.b.), barrel temperature ranging from 80°C to 140°C and die size of 1.88mm. The extrudates were dried at 50°C overnight and further analysed. Results showed that an increase in extruder barrel temperature decreased the residence time of the flours in the extruder (from 4.11-11.32min to 2.24-6.76min), but increased the expansion ratio, rehydration ratio, water absorption index, water solubility index and b value of the extrudate (p≤0.05). The extrudates had the mean residence time and physical properties of rice flour<rice flour with potato starch<corn flour with potato starch<corn flour (p≤0.05). Results showed conclude that barrel temperature and flour types showed significant effect on the residence time and physical properties of the extrudates

Optimization of leavening agents in extruded gluten-free brewer's rice hard pretzel using response surface methodology

Celiac is the second most important issue in food sensitivities. The only treatment for celiac is a lifetime avoidance of consuming gluten. As pretzels are one of the most popular snacks in the world, making gluten-free pretzels is a market need. To produce gluten-free products, it is important to optimize the ingredients of the formulation. This research focused on optimization of the leavening agents of the most popular commercial hard pretzel formulation in which wheat flour is replaced with brewer's rice flour. This research also attempts to explain the effect of leavening agents in products containing no matrix molecules such as gluten. Response surface methodology via the central composite design was used to optimize the effects of yeast and bicarbonate of soda on the hardness (cutting strength), fracturability (brittleness), surface color, lateral expansion, expansion ratio, specific length, density (bulk, particle, material), porosity (open, close, total), water absorption index, water solubility index, water holding capacity, oil absorption index and oil holding capacity of gluten-free hard pretzel. The optimized results indicated that the gluten-free pretzel requires 8.05g yeast and 2.59g bicarbonate of soda for every 500g of brewer's rice flour