Pectin is a heterogeneous branched polysaccharide with complex structure. Microwave-assisted
extraction (MAE) is more efficient in extracting pectin compared to conventional method. The objective of this study was to compare the efficiency of microwave-assisted pectin extraction against conventional extraction method. This study was also to investigate the effect of power level on yield and quality of extracted pectin from jackfruit rinds. Water-based extraction method was performed with the extraction duration for conventional extraction and MAE were 1 h and 10 min, respectively. The temperature of conventional extraction was set at 90°C and the power levels of MAE were 450 W, 600 W and 800 W. High yield of pectin was obtained from conventional extraction (14.59%) and MAE (16.72-17.63%). All quality characteristics determined were found to be insignificant different for pectin extracted from both conventional extraction and MAE except moisture and ash content. Increase in microwave power did not affect yield and quality characteristics of pectin from jackfruit rinds significantly. In conclusion, MAE requires shorter time than conventional extraction in extracting comparable amount and quality of pectin from jackfruit rinds. Microwave-assisted extraction at 450 W was the most effective and economic extraction condition among the different power levels tested.
Changes in the physicochemical properties of wheat, sago, tapioca and potato starches were studied
after heating for 1 hour at 100oC, 110oC, and 120oC and for 2 hours at 120oC. These properties were characterised through the swelling behaviour of starch granules, amount of carbohydrate materials leached from the granules, starch paste retrogradation rate and gel strength. For all starches except wheat, the swelling ability, rate of retrogradation and gel strength decreased while solubility increased with increasing temperature and heating time. Wheat starch followed this pattern only when heated at 120oC for 1 and 2 hours. Gel strength correlated well with the ratio of amylose to amylopectin (R) in the leachate. To produce fried crackers with good expansion properties, the granule has to be sufficiently degraded so as to allow more amylopectin to be leached out to achieve R value of 0.25-0.5. This can be achieved by heating wheat starch at 120oC for 1 hour or longer.
Pulsed light (PL) treatment is a non-thermal method for microbial decontamination on the
surfaces of fresh-cut produce. The effect of pulsed light fluencies on microbiological stability
and quality changes of fresh-cut yardlong beans were determined. Pulsed light treatments were
carried out using an automatic laboratory flash lamp system (Steribeam XeMaticA-2L Kehl,
Germany) at different fluencies (1.8 J/cm2, 5.4 J/cm2, 9.0 J/cm2 and 12.6 J/cm2). Microbiological
quality (colour changes and textural changes) of fresh-cut yardlong beans stored at 4±1°C were
monitored over 14 days. Results show that, the application of PL treatment at high fluencies
allowed extension of microbiological shelf life up to 3-7 days in comparison to untreated
samples. Apart from that, PL treated sample has no significant difference on the texture and
colour as compared to untreated sample of fresh-cut yardlong bean. As a conclusion, the
application of PL at dose 9.0 J/cm2 has increased the shelf life of fresh-cut yardlong bean while
maintaining the quality when stored at 4±1°C.
Cassava chips that exist in the current market have no standardisation and cannot be stacked
nicely into cylindrical container. The objectives of this work are to determine the different dimension of cassava chips produced with different thickness and to develop stackable chips during mass production. Fresh cassava tubers were harvested, washed, peeled and sliced. The thickness measurements used were 1.0 mm, 1.5 mm, 1.75 mm and 2.0 mm and 1.27 mm thickness was measured from commercial potato chips as a controlled sample. Then, it was fried in deep fat fryer with the temperature of 170°C. For each thickness studied, different
numbers of slice (10, 20, 30 and 40 slices) were fried simultaneously. Results showed that there
are 6 shapes of fried chips produced during the frying. To conclude, thickness of the slice and
number of slices fried simultaneously give impact towards the shape of fried chip.
Consumers today prefer to purchase ready-to-eat, fresh-cut fruit that is readily available at the markets and retailers. They generally select the fresh-cut fruit base on the quality, freshness, nutrition and safety. The effects of packaging condition on fresh-cut Cantaloupe were studied during 18 days of storage at 2°C and 87% RH. Fresh-cut Cantaloupe pieces were packed in a Polypropylene (PP) container. As a control, the container was cover with lid without film, while Sample 1 (S1) was sealed only by a 40 μm PP film and Sample 2 (S2) was sealed with a 40 μm PP film and then adding the lid cover. Changes in colour, firmness Total Soluble Solids (TSS), pH, Titratable Acidity (TA) and Total Plate Count (TPC) were evaluated over time. During storage, it was found that the firmness significantly decreased from day 0 until day in all packaging conditions. Color parameters Luminosity (L*) and Chromaticity (C) were significantly change at the significance level of 95% (p
This work describes the effects of different cooking temperatures in repetitive cooking-chilling (RCC) process on resistant starch (RS) content in fish crackers prepared in a ratio of 1:1 fish to sago starch formulation. In this work, three sets of four RCC cycles were performed on fish crackers, in which each set was cooked at fixed temperatures of 100, 115 and 121°C, respectively. The chilling temperature was fixed at 4°C in all cases. Subjecting the fish crackers to a higher cooking temperature for up to 4 cycles of RCC can increase the RS content. However, quality degradation was observed in the characteristics of the fish crackers. During the first RCC cycle, cooking at a higher temperature had caused the crackers to crack and burst. Besides, defragmentation to the shape of the fish cracker gels was also observed during the first RCC cycle, coupled with softer texture and high moisture content. When the products were subjected to frying, their linear expansion decreased, the texture became harder and the colour turned darker. This work demonstrated that the application of higher cooking temperature up to 4 RCC cycles was able to enhance the RS content in the fish crackers, but it was less able to attain the product's perfect shape. On the contrary, fish crackers that were exposed to lower cooking temperatures contained lower RS but with less shape damage.
This study investigated the effect of citric, nitric and sulfuric acid on the yield and
physicochemical properties of pectin extracted from jackfruit and chempedak fruit rinds. Yield
and physicochemical properties such as uronic acid content, degree of esterification, degree of
acetylation and colour of pectin solution were determined and compared. Yield of pectin from
jackfruit and chempedak fruit rinds with nitric acid as extractant were 14.81 ± 1.02% and 17.62
± 0.69%, respectively, which were the lowest. The uronic acid content of all extracted pectin
was more than 65%. All jackfruit and chempedak fruit rind pectins in this study were high
methoxyl pectin with degree of esterification ranging from 72-75% for jackfruit rind pectin and
66-69% for chempedak rind pectin. The degree of acetylation of all extracted pectin was lower
than 1%. For both jackfruit and chempedak fruit rind pectins, the citric acid-extracted pectin
produced darker, more reddish and yellowish solution and thus is least preferable. Among
the acids studied, sulfuric acid was the best extractant due to the high yield of pectin and the
solution of this pectin was brighter, less reddish and yellowish.
The objective of the present work was to investigate the effects of alginate coating combined with repetitive pulsed light (RPL) treatment on the enzymatic activity of fresh-cut cantaloupes during chilled storage. Fresh-cut cantaloupes were coated with alginate (1.86%, w/v) followed by RPL treatment (0.9 J/cm2 at every 48 h up to 26 d) during storage. Untreated samples and samples with alginate or RPL alone were used as controls. Enzymatic activities [polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), peroxidase (POD), pectinesterase (PE), polygalacturonase (PG), pectate lyase (PEL), β-galactosidase (β-Gal), α-arabinofuranosidase (α-AF) and cellulase] of fresh-cut cantaloupes were evaluated every 4 d during storage. Neither alginate coating nor RPL treatment has any effect on the activities of PE and PEL of freshcut cantaloupes during storage. The individual treatment or in combination did not increase the PAL, PPO, PG and cellulase activities of fresh-cut cantaloupes throughout the storage. Alginate coating with or without RPL was effective in maintaining low POD activity of freshcut cantaloupes. In addition, treatments using alginate coating or alginate coating+RPL were effective in reducing the β-Gal and α-AF activities of fresh-cut cantaloupes during storage. Overall, alginate without or with RPL was effective in reducing changes of enzymatic activities in fresh-cut cantaloupes during storage.
In this study, the effect of different solvent including ethanol, n-hexane and ethyl acetate on antioxidant
activity and total phenolic content (TPC) of winter melon (Benincasa hispida) seeds extract was investigated using conventional Soxhlet extraction (CSE). DPPH and ABTS scavenging activity and TPC results indicated that the seed extracts obtained using ethanol possessed the highest antioxidant activity and followed by ethyl acetate and n-hexane. By considering obtained results, it was clear that there was a high positive correlation between TPC and antioxidant activity. Linoleic acid forms a significant percentage of unsaturated fatty acids of the seed extract (60.6%). It is well known that essential fatty acids including linoleic acid and linolenic acid which are detected in extracts play important roles in preventing many disease and abnormal differentiation problems. B. hispida seeds are potential source of natural antioxidant compounds to replace synthetic antioxidants.
This study was undertaken to characterize the antibiotic resistance and randomly amplified polymorphic DNA (RAPD) profiles of Vibrio parahaemolyticus isolates from raw vegetable samples. A total of 46 isolates of V. parahaemolyticus recovered from raw vegetables samples and were confirmed by PCR were analyzed in this study. Most of the isolates were resistant to nalidixic acid (93.48%) and were the least resistant towards imipinem (4.35%). The MAR index results also demonstrated high individual and multiple resistances to antibiotics among the isolates. From the RAPD analysis, the size for RAPD fragments generated ranged from 250 bp to 1,500 bp, with most of the strains contained three major gene fragments of 350, 1,000 and 1,350 bp. The RAPD profiles revealed a high level of DNA sequence diversity within the isolates. Antibiotic resistance and RAPD proved to be effective tools in characterizing and differentiating the V. parahaemolyticus strains.