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Rheological and microstructural characteristics of thermally produced flaxseed gum-whey protein isolate mixed solutions and gels

  • Authors: Zhang, Yu , Li, Dong , Wang, Li-jun , Adhikari, Benu
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Drying Technology Vol. 31, no. 13-14 (2013), p. 1635-1642
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  • Description: The rheological, thermal gelation, and microstructural properties of flaxseed gum-whey protein isolate (WPI) mixtures were studied using steady shear viscometry, small amplitude oscillatory rheometry, differential scanning calorimetry (DSC), and confocal laser scanning microscopy (CLSM). The concentration of flaxseed gum was varied from 0.1%-0.5% (w/w) while the concentration of WPI was maintained at 20% (w/w). The addition of flaxseed gum increased the viscosity of flaxseed gum-WPI solutions and the strength of the mixed gels. The degree of increase in gel strength was found to depend on the concentration of flaxseed gum. The gel strength of the flaxseed gum-WPI mixed gels increased with the increase of flaxseed gum at low gum concentrations (0.1%-0.3% w/w). The gel strength of these mixed gels decreased (but it was still higher than WPI only gel) at high flaxseed gum concentration (0.5% w/w) due to excessive phase separation caused by thermodynamic incompatibility. This phase separation was clearly visible in micrographs obtained from CLSM. © 2013 Copyright Taylor and Francis Group, LLC.
  • Description: C1

Spray drying and encapsulation of omega-3 oils

Survival, fermentation activity and storage stability of spray dried Lactococcus lactis produced via different atomization regimes

  • Authors: Ghandi, Amir , Powell, Ian , Broome, Melcolm , Adhikari, Benu
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Journal of Food Engineering Vol. 115, no. 1 (2013), p. 83-90
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  • Description: Dried powders containing Lactococcus lactis ssp. cremoris were produced using laboratory and pilot scale spray dryers with lactose:whey protein isolate (3:1) as a protective medium. The effects of storage temperature (25, 4 and -18 °C) and time (30, 60 and 90 days) were studied. The survival and fermentation activity of the dried bacterial cells were significantly lower when the powders were stored at 25 °C compared to those stored at 4 and -18 °C; powders stored at 4 and -18 °C were statistically similar. The survival and fermentation activity of bacterial cells obtained from a laboratory scale two-fluid nozzle spray dryer were found to be higher than those of cells obtained from a pilot scale two-fluid spray dryer. A rotary wheel atomizer gave significantly higher survival and activity in the same dryer. These observations are consistent with cell damage due to high characteristic shear rates in the atomization process in nozzle type atomizers. The presence of ascorbic acid (oxygen scavenger) in the powder composition was found to improve both the survival and the maintenance of fermentation activity of the dried bacterial cells significantly during storage. The survival and fermentation activity of dried bacterial cells in stored powders indicated that these parameters are system-specific and can be strongly affected by the storage temperature and presence or absence of antioxidant, and also by upstream processing conditions such as the mode of atomization and presence or absence of antioxidants in the dryer feed. © 2012 Elsevier Ltd. All rights reserved.
  • Description: 2003010581

Suspensions of vacuum-freeze dried starch nanoparticles : Influence of NaCl on their rheological properties

  • Authors: Shi, Aimin , Wang, Li-jun , Li, Dong , Adhikari, Benu
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Carbohydrate Polymers Vol. 94, no. 2 (2013), p. 782-790
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  • Description: The effect of addition of NaCl on rheological properties of suspensions containing vacuum freeze dried starch nanoparticles was studied. These starch nanoparticles were produced through high pressure homogenization and emulsion cross-linking technique. Rheological properties such as continuous shear viscosity, storage and loss moduli and creep-recovery were measured. The presence of NaCl at concentration (5-15%, w/v) increased viscosity marginally (p > 0.05) while at 20% (w/v) it significantly (p < 0.05) increased viscosity. The presence of NaCl enhanced heat stability and weakened gelling capacity of suspensions. NaCl concentration below 15% (w/v) marginally (p > 0.05) increased the storage and loss moduli of suspensions. At 20% (w/v), NaCl increased both moduli significantly (p < 0.05) within frequency range tested (0.1-10 rad/s). Creep-recovery behavior was affected by NaCl and recovery rate was the highest (98.6%) at 20% (w/v) NaCl. The Cross, Power Law and Burgers' models followed experimental shear viscosity, storage and loss moduli and creep-recovery data reasonably well ((R
  • Description: 2003010855

The adsorption and release characteristics of CPFX in porous starch produced through different drying methods

  • Authors: Gao, Fei , Li, Dong , Bi, Chonghao , Mao, Zhihuai , Adhikari, Benu
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Drying Technology Vol. 31, no. 13-14 (2013), p. 1592-1599
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  • Description: The drug adsorption and release characteristics of porous starches produced through hot air drying, spray drying, and vacuum freeze drying were investigated using ciprofloxacin as model drug. A UV/visible spectrophotometer, Fourier-transform infrared spectrometer, differential scanning calorimeter, and X-ray diffractometer were used to determine the drug adsorption/release, drug/starch interaction, glass transition, and crystallinity of porous starch samples. The amount of ciprofloxacin adsorbed in three different porous starches was 5.58%, 8.91%, and 11.43%, respectively. The ciprofloxacin-loaded porous starches had glass-transition-related endothermic peaks between 55°C and 65°C and melting-related endothermic peaks between 120°C and 150°C. Up to 75% of the loaded ciprofloxacin was released from the freeze-dried sample within 30 hrs. The freeze-dried porous starch also showed higher ciprofloxacin loading rate, higher glass transition temperature, and higher ciprofloxacin release rate. A two-phase dynamic drug release model was found to satisfactorily fit the release kinetics of ciprofloxacin (R2 > 0.995). © 2013 Copyright Taylor and Francis Group, LLC.
  • Description: C1

The effect of partial gelatinization of corn starch on its retrogradation

  • Authors: Fu, Zong-qiang , Wang, Li-Jun , Li, Dong , Zhou, Yuguang , Adhikari, Benu
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Carbohydrate Polymers Vol. 97, no. 2 (2013), p. 512-517
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  • Description: The objective of this work was to investigate the effect of partial gelatinization of starch on its retrogradation using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. The Avrami equation was used to predict the evolution of starch retrogradation kinetics. The degree of retrogradation in starch samples partially gelatinized 64 ?C (S64), 68 ?C (S68) and 70 ?C (S70) and control (S25) increased with storage time. The retrogradation enthalpies of S68 and S70 were almost four times as high as that of S64. The S25 and S64 had dominant A-type crystalline pattern while S68 and S70 showed dominant B-type crystalline pattern. The growth of remainder crystals was faster in S25 and S64, while both the nucleation and growth rates of new crystals were faster in S68 and S70. The Avrami model was found to represent the retrogradation kinetics data of these partially gelatinized starch samples quite satisfactorily (R2 > 0.95). © 2013 Elsevier Ltd. All rights reserved.
  • Description: C1

The inactivation kinetics of polyphenol oxidase in mushroom (Agaricus bisporus) during thermal and thermosonic treatments

  • Authors: Cheng, X. , Zhang, Min , Adhikari, Benu
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Ultrasonics Sonochemistry Vol. 20, no. 2 (2013), p. 674-679
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  • Description: The effect of thermal and thermosonic treatments on the inactivation kinetics of polyphenol oxidase (PPO) in mushroom (Agaricus bisporus) was studied in 55-75°C temperature range. In both the processes, the inactivation kinetics of PPO followed a first-order kinetics (R2 = 0.941-0.989). The D values during thermal inactivation varied from 112 ± 8.4 min to 1.2 ± 0.07 min while they varied from 57.8 ± 6.1 min to 0.88 ± 0.05 min during thermosonic inactivation at the same temperature range. The activation energy during thermal inactivation was found to be 214 ± 17 kJ/mol, while it was 183 ± 32 kJ/mol during thermosonic inactivation. The inactivating effect of combined ultrasound and heat was found to synergistically enhance the inactivation kinetics of PPO. The D values of PPO decreased by 1.3-3 times during thermosonic inactivation compared to the D values of PPO during thermal inactivation at the temperature range. Therefore, thermosonication can be further developed as an alternative to "hot break" process of mushroom. © 2012 Elsevier B.V. All rights reserved.
  • Description: 2003010582

The physicochemical characteristics and hydrophobicity of high amylose starch-glycerol films in the presence of three natural waxes

  • Authors: Muscat, Delina , Adhikari, Raju , McKnight, Stafford , Guo, Qipeng , Adhikari, Benu
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Journal of Food Engineering Vol. 119, no. 2 (2013), p. 205-219
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  • Description: The film forming behaviour and hydrophobicity of high amylose (HA) starch in the presence of three different natural waxes (beeswax, candelilla wax and carnauba wax) were studied in the presence and absence of Tween-80. The HA starch:glycerol (G) ratio was maintained at 80:20 (on dry solid basis) and the concentration of wax was varied from 5% and 10% (w/w). The melted wax samples were homogenized with HAG dispersion with or without Tween-80 and the films were prepared by solution casting. The hydrophobicity and water-barrier properties in these films were determined by using contact angle (CA), water vapour permeability (K
  • Description: 2003011133

The survival of lactococcus lactis in a convective-air-drying environment: The role of protectant solids, oxygen injury, and mechanism of protection

  • Authors: Ghandi, Amir , Powell, Ian , Chen, Xiao Dong , Adhikari, Benu
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Drying Technology Vol. 31, no. 13-14 (2013), p. 1661-1674
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  • Description: The effect of protectant solids (lactose, sodium caseinate, and their mixture) on the survival of Lactococcus lactis subsp. cremoris was studied in a convective-air-drying environment using single droplet drying. The effect of drying the bacteria in the presence or absence of sodium ascorbate was evaluated, and the evolution of glass transition temperature in the drying process was examined. It was found that the protective efficiency of lactose and sodium caseinate was comparable at the concentrations tested. A mixed protectant matrix (lactose:sodium caseinate, 3:1) gave higher survival than with lactose or sodium caseinate alone at the same total solids level. Protectants enhanced bacterial survival by moderating the drying rate and achieving dryness at lower temperatures, and by facilitating the formation of a glassy matrix earlier in the drying process. The addition of sodium ascorbate was also examined. © 2013 Copyright Taylor and Francis Group, LLC.
  • Description: C1

Viscoelastic properties and fractal analysis of acid-induced SPI gels at different ionic strength

  • Authors: Bi, Chonghao , Li, Dong , Wang, Li-jun , Adhikari, Benu
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Carbohydrate Polymers Vol. 92, no. 1 (January 2013), p. 98-105
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  • Description: The viscoelastic property and scaling behavior of acid (glucono-delta-lactone)-induced soy protein isolate (SPI) gels were investigated at various ionic strengths (0-800 mM) and five protein concentrations ranging between 4% and 8% (w/w). The infinite storage modulus (G '(infinity)) and the gelation start time (t(g))which indicate the progress of gelation process exhibited strong ionic strength dependence. The storage modulus and critical strain were found to exhibit a power-law relationship with protein concentration. Rheological analysis and confocal laser scanning microscopy (CLSM) analysis were applied to estimate the fractal dimensions (D-f) of the gels and the values were found to vary between 2.319 and 2.729. The comparison of the rheological methods and the CLSM image analysis method showed that the Shih, Shih, Kim, Liu, and Aksay (1990) model was better suited in estimating the D-f value of acid-induced SPI gel system. (C) 2012 Elsevier Ltd. All rights reserved.
  • Description: C1

Yield and characteristics of pyrolysis products obtained from Schizochytrium limacinum under different temperature regimes

  • Authors: Li, Gang , Zhou, Yuguang , Ji, Fang , Liu, Ying , Adhikari, Benu , Tian, Li , Ma, Zonghu , Dong, Renjie
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Energies Vol. 6, no. 7 (2013), p. 3339-3352
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  • Description: Pyrolysis-gas chromatographic mass spectrometry (Py-GC/MS) was used to determine the yield and chemical composition of the pyrolysis products of Schizochytrium limacinum. The pyrolysis was carried out by varying the temperature from 300 °C to 800 °C. It was found that the main decomposition temperature of Schizochytrium limacinum was 428.16 °C, at which up to 66.5% of the mass was lost. A further 18.7% mass loss then occurred in a relatively slow pace until 760.2 °C due to complete decomposition of the ash content of Schizochytrium limacinum. The pyrolysis of Schizochytrium limacinum at 700 °C produced the maximum yield (67.7%) of pyrolysis products compared to 61.2% at 400 °C. While pollutants released at 700 °C (12.3%) was much higher than that of 400 °C (2.1%). Higher temperature will lead to more pollutant (nitrogen compounds and PAHs) release,which is harmful to the environment. Considering the reasonably high yield and minimum release of pollutants, a lower pyrolysis temperature (400 °C) was found to be optimum for producing biofuel from Schizochytrium limacinum.
  • Description: C1

Application of high pressure argon treatment to maintain quality of fresh-cut pineapples during cold storage

  • Authors: Wu, Zhi-Shuangyou , Zhang, Min , Adhikari, Benu
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Journal of Food Engineering Vol. 110, no. 3 (2012), p. 395-404
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  • Description: High pressure (HP) argon (Ar) treatment was applied to preserve fresh-cut pineapples at 4°C. The effects of treatment temperature (2-10°C), time (30-120 min) and pressure (0.5-4.5 MPa) on the efficiency of pressurized Ar treatment was studied to determine the optimum conditions. Temperature in the range of 2-6°C did not significantly affect the efficacy of the pressurized Ar treatment. A combination of pressure-time of pressurized Ar treatment at 1.6-2.2 MPa for 43-65 min was found to be the optimum processing conditions for the preservation of pineapple slices. Samples treated at optimum condition (1.8 MPa, 60 min) were stored at 4°C for 20 days to evaluate the effect of HP Ar treatment on nutritional components, microbial growth, sensory quality, membrane permeability and microstructure. A shelf life extension of 6 days was achieved by applying HP Ar treatment for fresh-cut pineapples during cold storage in air or in modified atmospheric packaging. © 2012 Elsevier Ltd. All rights reserved.

Drying kinetics and survival studies of dairy fermentation bacteria in convective air drying environment using single droplet drying

  • Authors: Ghandi, Amir , Powell, Ian , Chen, Xiao Dong , Adhikari, Benu
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Journal of Food Engineering Vol. 110, no. 3 (2012), p. 405-417
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  • Description: The drying and survival kinetics of Lactococcus lactis ssp. cremoris in a convective air drying environment were measured using single droplet drying experiments. Tests were carried out at five different drying temperatures (45-95°C) at a constant air velocity (0.5 m/s) and within 2.4-11% relative humidity. The effect of protective agents (10% w/w) of lactose, sodium caseinate and lactose:sodium caseinate (3:1) was also evaluated. The thermal inactivation kinetics parameters in convective air drying and isothermal water bath heating were determined and compared. The results showed that the final temperature attained by the droplet affected the survival of the bacteria significantly, however, most of the bacterial death occurred in early stage of drying while evaporative cooling kept the drop temperature relatively low. At higher droplet temperatures (≥65°C) the bacterial cultures were inactivated by both dehydration and thermal stresses. At lower droplet temperatures (≤55°C) the rate of change in droplet moisture content had much stronger effect on the bacterial survival. Lactose and sodium caseinate, as protective agents, enhanced the survival of bacterial cells significantly at all the test conditions. The lactose:sodium caseinate (3:1) mixture synergistically enhanced the survival of the bacterial cultures. The death of these bacteria followed first-order kinetics during convective single droplet drying as well as during isothermal water-bath heating. However, the inactivation energy in convective single droplet drying (181.3 kJ/mol) was much higher than the inactivation energy in isothermal water bath heating (16.8 kJ/mol) within the medium temperature of 45-95°C. © 2012 Elsevier Ltd. All rights reserved.

Effect of high-pressure homogenization on microstructure and rheological properties of alkali-treated high-amylose maize starch

  • Authors: Wang, Bao , Li, Dong , Wang, Li-jun , Liu, Yan-hong , Adhikari, Benu
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Journal of Food Engineering Vol. 113, no. 1 (2012), p. 61-68
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  • Description: The effect of high-pressure homogenization (HPH) on the microstructure, rheological properties, paste clarity, as well as gel retrogradation behavior of alkali-gelatinized high-amylose maize starch (HMS) was investigated. The alkali-treated HMS pastes were subjected to HPH at homogenizing pressures of 25, 50, 75, 100, and 125 MPa. After HPH treatment, the uniformity in the microstructure of HMS pastes was greatly increased. At homogenizing pressures greater than 100 MPa, starch ghost particles were found to completely disappear. The apparent viscosity of the HMS pastes was found to decrease significantly due to the application of HPH. The paste clarity of the HMS pastes increased when HPH treatment was applied. After storing at 4 °C for 7 days, HMS pastes homogenized at 50 and 100 MPa displayed weaker viscoelastic behavior than their corresponding unhomogenized pastes. This indicated that HPH treatment is capable of inhibiting starch retrogradation in gels. © 2012 Elsevier B.V. All rights reserved.

Effect of shear rate and oxygen stresses on the survival of Lactococcus lactis during the atomization and drying stages of spray drying : A laboratory and pilot scale study

  • Authors: Ghandi, Amir , Powell, Ian , Howes, Tony , Chen, Xiao Dong , Adhikari, Benu
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Journal of Food Engineering Vol. 113, no. 2 (2012), p. 194-200
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  • Description: The effect of shear rate and oxygen injury during atomization and the combination of these factors on the survival of Lactococcus lactis subsp. cremoris in spray drying was studied using laboratory and pilot scale spray dryers. The atomization was carried out using a two-fluid nozzle in the laboratory study and a two-fluid nozzle or rotary atomizer in the pilot scale study. The extent of oxygen-induced death was determined using ascorbic acid in the feed and atomizing the feed with gaseous nitrogen. The lowest levels of bacterial death were observed at lowest characteristic shear rate and in the presence of nitrogen and ascorbic acid. Quantitative analysis showed that lower shear rate, creating an oxygen-limiting environment during atomization and drying, and using oxygen scavengers in the feed were successful in enhancing bacterial survival in spray drying. We also report for the first time that, at least for L. lactis, the extent of death during the atomization stage far outweighs death during the drying stage, and that the majority of bacterial death (up to 93%) occurs during the atomization stage. The death of bacteria was found to be less when using a rotary atomizer or when using a two-fluid nozzle atomizer at lower flow rate. This work shows that bacterial death during spray drying can be minimized by using oxygen scavengers such as ascorbic acid and/or an anaerobic atomizing medium (such as nitrogen), and by altering the spraying conditions. © 2012 Elsevier Ltd. All rights reserved.

Effects of partial gelatinization on structure and thermal properties of corn starch after spray drying

  • Authors: Fu, Zong-qiang , Wang, Li-jun , Li, Dong , Adhikari, Benu
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Carbohydrate Polymers Vol. 88, no. 4 (2012), p. 1319-1325
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  • Description: Partially gelatinized starch was prepared by gelatinizing corn starch at 64-72°C followed by spray drying (inlet temperature, feed flow rate, air flow rate of 200°C, 7.2 ml/min and 0.375 m 3/h, respectively). The morphology, granule size, crystalline fraction, swelling power and gelatinizing properties of partially gelatinized starch were investigated and compared with those of native starch. The surface morphology of partially gelatinized starch granules was shriveled with multiple surface folds. The granule size of partially gelatinized starch was smaller than that of native corn starch. There was either complete absence of crystalline fraction in partially gelatinized starch or the extent of crystalline fraction was greatly reduced. The swelling power of partially gelatinized starch was higher than that of the native starch below 60°C, while it was lower than that of native starch above 60°C. There was an increase in gelatinization temperature and a decrease in gelatinization enthalpy in partially gelatinized starch compared to that of native starch. © 2012 Elsevier Ltd. All rights reserved.

Extending shelf-life of fresh-cut green peppers using pressurized argon treatment

  • Authors: Meng, Xiangyong , Zhang, Min , Adhikari, Benu
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Postharvest Biology and Technology Vol. 71, no. (2012), p. 13-20
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  • Description: When fresh-cut fruit and vegetables are subjected to pressurized argon treatments, the argon gas dissolves into water and forms clathrate hydrates which ultimately lead to restriction in water mobility. In this study, fresh-cut green peppers were subjected to pressurized (2-6MPa) argon treatments for 1h. The untreated (control) and argon-treated samples were placed in polystyrene packaging with 5% O 2 and 8% CO 2 and then stored at 4°C and 90% RH for 12d. Various quality parameters of fresh-cut green peppers treated at 2, 4 and 6MPa of argon were compared with those of the control. Water loss, ascorbic acid loss, visual sensory quality, malondialdehyde (MDA), cell membrane permeability, cell protective enzyme activity and microbial quality were determined every 2d. Water mobility and loss of water in fresh-cut green peppers was greatly reduced by the pressurized argon treatment. Similarly, the loss of ascorbic acid, chlorophyll content and hue angle was also reduced during storage. The pressurized argon treatments were found to maintain the cell integrity by inhibiting an increase in MDA and membrane permeability compared to the control samples. The activities of catalase (CAT) and peroxidase (POD) were inhibited by the pressurized argon treatment. The treatment also reduced proliferation of spoilage microorganisms such as coliforms, yeasts and moulds. The fresh-cut green peppers treated by pressurized argon at 4MPa for 1h could be kept in a fresh-like condition for 12d at 4°C. © 2012 Elsevier B.V.

Interfacial and emulsifying properties of lentil protein isolate

  • Authors: Joshi, Matina , Adhikari, Benu , Aldred, Peter , Panozzo, Joe , Kasapis, Stefan , Barrow, Colin
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Food Chemistry Vol.134 no.3 (2012), p.343-1353
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  • Description: The dynamic interfacial tension (DIFT) at oil-water interface, diffusion coefficients, surface hydrophobicity, zeta potential and emulsifying properties, including emulsion activity index (EAI), emulsion stability index (ESI) and droplet size of lentil protein isolate (LPI), were measured at different pH and LPI concentration, in order to elucidate its emulsifying behaviour. Sodium caseinate (NaCas), whey protein isolate (WPI), bovine serum albumin (BSA) and lysozyme (Lys) were used as benchmark proteins and their emulsifying property was compared with that of LPI. The speed of diffusion-controlled migration of these proteins to the oil/water interface, was in the following order: NaCas > LPI > WPI > BSA > Lys, while their surface hydrophobicity was in the following order: BSA > LPI > NaCas > WPI > Lys. The EAI of emulsions stabilised by the above proteins ranged from 90.3 to 123.3 m 2/g and it was 93.3 ± 0.2 m 2/g in LPI-stabilised emulsion. However, the stability of LPI-stabilised emulsions was slightly lower compared to that of WPI and NaCas-stabilised emulsions at the same protein concentration at pH 7.0. The ESI of LPI emulsions improved substantially with decrease in droplet size when protein concentration was increased (20-30 mg/ml). Reduction of disulphide bonds enhanced both the EAI and ESI compared to untreated samples. Heat treatment of LPI dispersions resulted in poor emulsion stability due to molecular aggregation. The stability of LPI-stabilised emulsions was found to decrease in the presence of NaCl. This study showed that LPI can be as effective emulsifiers of oil-in-water emulsions as are WPI and NaCas at ≥20 mg/ml concentrations both at low and neutral pH. The emulsifying property of LPI can be improved by reducing the intra and inter-disulphide bond by using appropriate reducing agents. © 2012 Elsevier Ltd. All rights reserved.

Investigation of relationship between surface tension of feed solution containing various proteins and surface composition and morphology of powder particles

  • Authors: Xu, Yun , Howes, Tony , Adhikari, Benu , Bhandari, Bhesh
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Drying Technology Vol. 30, no. 14 (2012), p. 1548-1562
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  • Description: The surface tension of freshly created food protein powder isolates was measured in aqueous solutions as a function of concentration, hydrolysis, and temperature. The surface tension of the solutions was measured immediately to best predict their surface-active behavior in a spray-drying scenario, where instantaneous values are more relevant than equilibrium surface tension measurements. Whole whey protein, hydrolyzed whey proteins (degrees of hydrolysis of 4, 9.5, 12, 17, and 20.2%), soy protein, pea protein isolates, and gelatin powders were diluted in a range of concentrations (0.04-2 g/L) and their surface tension values were reported at 23 +/- 1 degrees C. It was found that at higher concentrations hydrolyzed whey proteins at degrees of hydrolysis of 9.5 and 12%, and soy protein isolates in particular, showed excellent surface activity (shown through a decrease in surface tension) compared to nonhydrolyzed whey protein and gelatin. When comparing the influence of the degree of hydrolysis of whey proteins, the reverse was observed at lower concentrations (0.04-0.1 g/L), with the nonhydrolyzed whey protein reducing surface tension values more effectively than their hydrolyzed counterparts. Additionally, the protein solutions (2 g/L) were maintained at higher temperatures of 40, 50, and 60 degrees C and the surface tension values were measured. There was a general improvement of surface activity of proteins indicated by the reduced surface tension of solutions at these temperatures compared with the pure water values. The protein solutions were also spray dried with maltodextrin (MD30) and the powder particle surface composition and structures were analyzed via X-ray photoelectron spectroscopy and scanning electron micrography. There was a trend of correlation between the surface activities of protein in solution with that of the surface composition of protein found on the powder particles. However, there were morphological indicators that corresponded well to the amount of protein present on the surface.

Prediction of storage quality of fresh-cut green peppers using artificial neural network

  • Authors: Meng, Xiangyong , Zhang, Min , Adhikari, Benu
  • Date: 2012
  • Type: Text , Journal article
  • Relation: International Journal of Food Science and Technology Vol. , no. (2012), p.
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  • Description: To extend the shelf-life of fresh-cut fruits and vegetables, it is essential to develop models that can accurately predict their storage quality. In view of this, an artificial neural network (ANN) model based on back propagation (BP) algorithm was developed to predict the storage quality (degree of yellowness, water loss, textural firmness and vitamin C content) of fresh-cut green peppers. The prediction accuracy of ANN was compared with that of multiple linear regression-based models. The root mean square error (RMSE), mean absolute error (MAE), sum of squared residuals (SSR) and standard error of prediction (SEP) were used as comparison parameters. The results showed that the accuracy and goodness of fit of the storage quality parameters predicted by ANN were better than those predicted by multiple linear regression-based models. The RMSE, MAE, SSR and SEP values obtained from the former were much lower than those obtained from the latter. © 2012 The Authors. International Journal of Food Science and Technology © 2012 Institute of Food Science and Technology.