Control of Enzymatic Browning in Strawberry, Apple, and Pear by Physical Food Preservation Methods: Comparing Ultrasound and High-Pressure Inactivation of Polyphenoloxidase

Polyphenoloxidase (PPO) enzyme can be found in fruits, vegetables and crustaceans. Its activity, promoted by oxygen, causes food browning with subsequent loss of quality and limited shelf life. Foods are pasteurized with conventional and novel physical methods to inactivate spoilage enzymes, thus avoiding the addition of unhealthy chemical preservatives. Ultrasound and highpressure processing (HPP) are non-thermal technologies capable of retaining vitamins, bioactives and sensory components of fresh fruits. Enzyme residual activity vs. processing time were plotted for strawberry, apple, and pear purees subjected to thermosonication (1.3 W/g—71 C), HPP-thermal (600 MPa—71 C) and heat treatment alone at 71 C. The PPO residual activities after treatments were highly variable. TS was the most effective for inactivating PPO, followed by thermal processing. HPP-thermal did not improve the inactivation compared with thermal treatment at 71 C. The resistance of the three fruits’ PPOs exhibited the same pattern for the three technologies: pear PPO was the most resistant enzyme, followed by apple PPO and, lastly, strawberry PPO. However, the resistance of the three PPOs to TS was lower and very similar. Given the huge variability of PPO resistance, it is important to run inactivation tests for different fruits/cultivars. The results can assist manufacturers to avoid browning during processing, storage and distribution of fruit purees, juices and concentratesinfo:eu-repo/semantics/publishedVersio

Comparison of UV-C and thermal pasteurisation for the quality preservation of pineapple-mango juice blend

Massive grow in the juice industry promotes the development of the new flavour juice by blending two or more different types of fruits. Application of ultraviolet-irradiation of light spectrum C (UV-C) on single juice already widely explored whereas limited study was done on juice blend. Thus, the effect of ultraviolet-irradiation (UV-C) on physicochemical and antioxidant properties of pineapple-mango juice blend was investigated. Pineapple and mango juice blended together at blending ratio of 70 pineapple: 30 mango (volume/volume). Physicochemical properties of pH, total titratable acidity, total soluble solid and turbidity of pineapple-mango juice blends UV-C (UV-C dosage of 8.38mJ/cm²) and thermally (90°C, 5 mins) treated were significantly changes (p<0.05) during 9 weeks of storage at 4°C. Antioxidant qualities namely ascorbic acid, total phenolic compounds (TPC), and total antioxidant (as DPPH assay scavenging activities) of UV-C treated pineapple-mango juice blend shows higher values throughout the storage period. A Pearson correlation showed that ascorbic acid is the main contributor in antioxidant properties of pineapple-mango juice blend as decreased in ascorbic acid content caused degradation in TPC during storage. Present study proved that UV-C treatment better in nutritional and heat sensitive component retention compared to conventional thermal pasteurisation

Effect of ultraviolet irradiation (UV-C) on quality attributes of pineapple-mango juice blend compare with thermal pasteurization

This intended paper was done to give an early overview of the expected quality attributes of pineapple-mango juice blend treated with ultraviolet irradiation (UV-C) and thermal pasteurisation. Josapine pineapple (Ananas comosus L.) and Chokanan mango (Mangifera indica L.) is the popular tropical fruits in Malaysia with unique taste and constant availability. The blend of pineapple-mango juice predicted to have good overall quality attributes as proved by prior studies on orange-pineapple, lemon-melon, pineapple-carrot-orange and carrot-apple-banana juice blends. Conventional thermal pasteurisation widely implemented in juice industry but resulted in massive quality degradation. Thus, research on the non-thermal technology of UV-C widely studied to overcome such drawbacks of thermal pasteurisation. Effect of UV-C and thermal pasteurisation on pineapple-mango juice blend will be evaluated in terms of physicochemical (pH, titratable acidity, total soluble solids, turbidity and colour), antioxidant (ascorbic acid, total phenolics content and total antioxidant DPPH assay) and microbiological properties. UV-C treated pineapple-mango juice blend believed to have better retention of heat sensitive ascorbic acid and other quality compared heat pasteurised juice with minimal distinctive characteristic compared to fresh juice

UV-C effect on microbial disinfection of pineapple-mango juice blend using Dean-vortex technology

This study intended to evaluate the effect of ultraviolet irradiation (UV-C) treatment of Dean-vortex technology on pineapple-mango juice blend microbial safety. Non-thermal alternative treatment of UV-C known to be promising in juice processing but low penetration depth in opaque liquid resulted in enhancement of treatment using dean vortex. Dean vortex promotes mixing in helically arranged treatment tube. Two pump frequency was selected (40 and 45Hz) to be performed on pineapple-mango juice blend at blending ratio of 70%pineapple and 30% mango. The flow regimes inside the polyfluoroalcoxy (PFA) tube behave as turbulence as the effect of dean vortex for both flow rates of the pump which brought the targeted microorganism closer towards light source relatively improve treatment efficiency. Pathogenic E. coli O157: H7 that can cause fatality was inoculated into pineapple-mango juice blends. This study shows that at a UV-C dosage of 8.38mJ/cm² able to reduce E. coli O157: H7 more than 5 log reduction. Although UV-C treatment unable to fully disinfect yeast and mould counts in pineapple-mango juice blend, the detection colony was still under the permissible limit (1.26 log CFU/mL). These proved that UV-C treatment with the implementation of dean-vortex technology able to meet the microbial load safety limit comparable to commercialize practice using thermal pasteurization

Quality assessment of ozone-treated citrus fruit juices

The aim of the present work was to analyse the impact of ozone treatment on the physicochemical parameters and antioxidant capacity of citrus fruit juices (orange, lemon and lime) with different juice components (total soluble solids). Each sample was ozonated at different ozone treatment time, between 0 to 30 min with fixed ozone concentration of 600 mg/h. The synergistic effects of ozone treatment and the different types of juice were found to significantly affect the pH, total colour difference (TCD), pectin methylesterase (PME) activity, ascorbic acid (AA) and total phenolic content (TPC) of treated juices, while total soluble solids, turbidity and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay were found to be unchanged. It was observed that PME activity decreased with treatment time and this is related to the decrease of juice turbidity (R2 = 0.86) and TCD (R2 = 0.78). Ascorbic acid showed an abrupt decrease in all the juices especially in orange juice with percentage loss of 85%. TPC also showed decreasing trend for all juices with maximum loss of 84.4% in lemon juice after 30 min of ozonation time. The present work also found that lemon juice could retain most of its antioxidant activities (DPPH 98.9%, TPC 96%, AA 86.7%) after 10 min of ozone treatment time in comparison to orange and lime juices

Effect of High-Pressure Processing (HPP) on composition, lactose and microstructure of goat milk

Thermal pasteurisation is an established method for milk processing. However, the high temperature could affect the micronutrients in the milk. High pressure processing (HPP) is a cold alternative to thermal pasteurisation that can maintain the fresh-like properties of liquid food. However, employing pressure could potentially affect the composition and microstructure of milk and milk products. Therefore, this study focusses on evaluating the effect of high pressure processing (HPP) towards the composition, lactose content and microstructure (in term of fat globules) of goat milk. The goat milk was subjected to HPP at a pressure range of 200 to 600 MPa and process holding time at 5 - 15 mins. There were insignificant differences in terms of fat, protein and carbohydrate, but significant changes observed for lactose content of pressurised goat milk (PGM). The lactose content of PGM was in the range of (2.540 – 2.986 g/mL), while 1.253±0.01 g/100 mL for untreated goat milk (UGM). A higher number of the small size of goat milk fat globules observed at 600 MPa compared to lower processing pressure (200 and 400 MPa) at the same pressure holding time (5 to 15 mins). The mean diameters of fat globules were in the range of 5.215 to 5.651 μm. This size reduction of milk fat globules is an advantage for cheese making or other dairy product making industries, because it can help to possess a smoother and more refined texture of milk products

Quality stability and sensory attributes of apple juice processed by thermosonication, pulsed electric field and thermal processing

Worldwide, apple juice is the second most popular juice, after orange juice. It is susceptible to enzymatic browning spoilage by polyphenoloxidase, an endogenous enzyme. In this study, Royal Gala apple juice was treated by thermosonication (TS: 1.3 W/mL, 58 ℃, 10 min), pulsed electric field (PEF: 24.8 kV/cm, 60 pulses, 169 µs treatment time, 53.8 ℃) and heat (75 ℃, 20 min) and stored at 3.0 ℃ and 20.0 ℃ for 30 days. A sensory analysis was carried out after processing. The polyphenoloxidase activity, antioxidant activity and total color difference of the apple juice were determined before and after processing and during storage. The sensory analysis revealed that thermosonication and pulsed electric field juices tasted differently from the thermally treated juice. Apart from the pulsed electric field apple juice stored at room temperature, the processed juice was stable during storage, since the pH and soluble solids remained constant and fermentation was not observed. Polyphenoloxidase did not reactivate during storage. Along storage, the juices’ antioxidant activity decreased and total color difference increased (up to 6.8). While the antioxidant activity increased from 86 to 103% with thermosonication and was retained after pulsed electric field, thermal processing reduced it to 67%. The processing increased the total color difference slightly. No differences in the total color difference of the juices processed by the three methods were registered after storage. Thermosonication and pulsed electric field could possibly be a better alternative to thermal preservation of apple juice, but refrigerated storage is recommended for pulsed electric field apple juice

Sugar recovery from bakery leftovers through enzymatic hydrolysis : effect of process conditions and product characterization

This study evaluates the process conditions, (enzyme concentration (120-1200 U/g substrate), temperature (30-60 °C), and pH (3-9)) of enzymatic hydrolysis (EH) for sugar recovery from leftover croissants (LC) and leftover doughnut (LD), and characterizing its residue and hydrolysate. The highest sugar yield recovered from LC was 574.21 ± 0.74 mg/g (840 U/g substrate, 49 °C and pH 3) and for LD was 460.53 ± 0.74 mg/g (1176 U/g substrate, 47 °C and pH 3). The highest fructose and glucose yield for LC and LD were 14.47±0.73 mg/g and 11.84±0.21 mg/g, and 13.26±0.63 mg/g and 10.34±0.11 mg/g, respectively. Morphology analysis (SEM) showed that the structure of LC and LD had changes in its starch granules that indicates hydrolysis process occurrence. The presence of monosaccharides and oligosaccharides were detected from FTIR. HMF was also detected from sugar degradation due to EH, (0.043 ± 0.0334 mg/g for LC) and (0.023 ± 0.0124 mg/g for LD)

Consumers' delayed consumption of bakery products: effect on physical and chemical properties

Delay in the consumption of bakery products has contributed to the food waste problem, which is a serious global issue. Delayed consumption or can be regarded as the ‘leftovers’ bakery products such as croissants and doughnuts are normally discarded due to the impairment in texture or quality degradation causing them to taste not as good as fresh baked, although the products still edible. Thus, this study aims to evaluate the physical and chemical changes during the delaying of consumption of croissants and doughnuts at three (3) different storage times (day 0, 1 and 2). The hardness of croissants and doughnuts had an increased throughout storage time, with doughnuts have the higher hardness than croissants, with 175.63 % and 92.31 % increased, respectively. Carbohydrate was found as the major component for croissants and doughnuts. Croissants and doughnuts recorded carbohydrate content of (50.32-52.42 %) and (43.22-46.59 %), respectively, from day 0 to day 2. While sugar profile analysis detected three types of monosaccharides sugars, which were fructose, glucose and maltose for croissants and doughnuts. Thus, high content of carbohydrate and monosaccharides that available in the leftovers doughnut and croissants suggest that it could potentially be used as renewable resources for sugar recovery

Kinetic study of total phenolic content from Piper betle Linn. leaves extract using subcritical water

The green plant-based extraction of phenolic compounds is still challenging and attractive due to their benefit. The mechanism controlling of desorption rate of phenolic compounds, measured as total phenolic content (TPC), from Piper betle Linn. (PBL) leaves using subcritical water, and a one-site kinetic desorption model (first order) was studied. One-site kinetic desorption model has well explained the extraction mechanism of phenolic compounds from PBL leaves using subcritical water through desorption and diffusion mechanism. This model fits with the experimental data and presents a good description of the extraction mechanism with R-squared of 0.94. The recovery of TPC from PBL leaves using subcritical water was influenced by intraparticle diffusion, temperature, and extraction time. The desorption rate constant in the one-site kinetic desorption model increased from 100 to 200 °C (0.3975±0.02 to 3.3045±0.00 min-1)and then decreased to 250 °C (3.2093±0.00 min-1). The highest TPC was recovered quickly for 5 min at 200 °C. Inaddition, a high yield of TPC was also obtained at a slow desorption process for 30 min at a lower temperature of 175°C. The low activation energy for the diffusion of phenolic compounds from PBL leaves of this study was 8.964 kJ/mol.This result showed that the one-site kinetic desorption model of subcritical water extraction has an excellent opportunityto be applicable in phenolic compounds recovery from PBL leaves. The one-site kinetic desorption rate constant andmathematical kinetic model equation achieved in this study might control the quality of phenolic compounds extractedfrom PBL leaves through subcritical water