Impact of Enzymatic Hydrolysis and Heat Inactivation on the Physicochemical Properties of Milk Protein Hydrolysates

This study determined the physicochemical properties (apparent viscosity (ηapp ), turbidity (A550nm ), particle size and molecular mass distribution) of hydrolysates generated from whey protein concentrate (WPC), milk protein concentrate (MPC) and sodium caseinate (NaCN), following incubation with Debitrase HYW20™ and Prolyve™ at 50◦ C, pH 7.0 for 1 and 4 h, before and after heat inactivation (80◦ C for 10 min). The degree of hydrolysis (DH) increased with incubation time, giving values of 6.56%, 8.17% and 9.48%, following 1 h hydrolysis of WPC, MPC and NaCN with Debitrase HYW20™, and 12.04%, 15.74% and 17.78%, respectively, following 4 h incubation. These DHs were significantly higher compared to those obtained following 4 h incubation with Prolyve™. Hydrolysis with Debitrase HYW20™ gave >40% of peptides with molecular masses < 1 kDa for all substrates, which was higher than the value obtained following hydrolysis with Prolyve™. The effect of hydrolysis on the physicochemical properties was substrate dependent, since ηapp decreased in WPC and NaCN hydrolysates, particle size decreased for all the substrates, with aggregate formation for MPC, and turbidity decreased in WPC and MPC hydrolysates, while it increased in NaCN hydrolysates. The physical properties of the hydrolysates were influenced by the enzyme thermal inactivation step in a DH-dependent manner, with no significant effect on turbidity and viscosity for hydrolysates at higher DHs

Factors and conditions influencing the willingness of Irish consumers to try insects: a pilot study

peer-reviewedEntomophagy is being explored as a sustainable food source in Western countries to combat the ever-increasing effects of climate change. Studies conducted in various European countries determine the factors affecting willingness to consume insects. The current study aims to gain the first insight on this topic in Ireland, a country with a long farming tradition. A survey including open- and closed-ended questions was developed and sent to students and staff of an institute of technology in the West of Ireland. The willingness to consume insects and the factors affecting willingness to consume them under different conditions were assessed. It was found that less neophobic males who do not follow a particular diet were most receptive to entomophagy. People who were willing to try insects were less willing if the insects were to be eaten whole. People who were not willing were more inclined to do so if they were disguised or used to feed livestock. Food neophobia, disgust and safety concerns were barriers to acceptance. Tasty products containing disguised insects in familiar foods are the most likely to be accepted. Education and taste tests are recommended first steps to introducing entomophagy. Using insects to feed livestock has the potential to improve acceptance of entomophagy by introducing insects in the supply chain. However, further research should be conducted to assess acceptance of this amongst Irish farmers. The current study agrees with findings of studies conducted in other European countries and reveals the conditions under which insects could become acceptable among Irish consumers

The use of colloidal gas aphrons as novel downstream processing for the recovery of astaxanthin from cells of Phaffia rhodozyma

BACKGROUND: There is an increasing interest in obtaining natural products with bioactive properties, using fermentation technology. However, the downstream processing consisting of multiple steps can be complicated, leading to increase in the final cost of the product. Therefore there is a need for integrated, cost-effective and scalable separation processes. RESULTS: The present study investigates the use of colloidal gas aphrons (CGA), which are surfactant-stabilized microbubbles, as a novel method for downstream processing. More particularly, their application for the recovery of astaxanthin from the cells of Phaffia rhodozyma is explored. Research carried out with standard solutions of astaxanthin and CGA generated from the cationic surfactant hexadecyl. trimethyl ammonium bromide (CTAB) showed that up to 90% recovery can be achieved under optimum conditions, i.e., pH 11 with NaOH 0.2 mol L-1. In the case of the cells' suspension from the fermentation broth, three different approaches were investigated: (a) the conventional integrated approach where CGA were applied directly; (b) CGA were applied to the clarified suspension of cells; and finally (c) the in situ approach, where CGA are generated within the clarified suspension of cells. Interestingly, in the case of the whole suspension (approach a) highest recoveries (78%) were achieved under the same conditions found to be optimal for the standard solutions. In addition, up to 97% recovery of total carotenoids could be achieved from the clarified suspension after pretreatment with NaOH. This pretreatment led to maximum cell disruption as well as optimum conditioning for subsequent CGA separation. CONCLUSIONS: These results demonstrate the potential of CGA for the recovery of bioactive components from complex feedstock. (c) 2008 Society of Chemical Industry

Recovery of astaxanthin using colloidal gas aphrons (CGA): a mechanistic study

The aim of this study is to investigate the mechanism responsible for the recovery of astaxanthin using Colloidal Gas Aphrons (CGA), which are surfactant stabilised microbubbles. The latter were produced using different surfactant solutions (Cetyl Trimethyl Ammonium Bromide (CTAB)-cationic, Sodium Dodecyl Sulfate (SDS)-anionic, TWEEN 60-non-ionic and mixtures of TWEEN 60-SPAN 80- non-ionic with varying hydrophobicity) at stirring speed 8000 rpm and stirring time 5 min. Experiments were carried out at varying pH and volumetric ratios of astaxanthin to CGA, and with two different astaxanthin standard suspensions: (i) astaxanthin dispersed in aqueous solutions and (ii) astaxanthin dispersed in ethanolic/aqueous solutions with different compositions of ethanol (20/80 (v/v) and 40/60 (v/v)). When astaxanthin is dispersed in aqueous solutions the separation seems to occur mainly by electrostatic interactions. Therefore the recoveries are higher in the case of the cationic surfactant when astaxanthin particles are strongly negatively charged, as shown by the zeta potential measurements. When ethanol is present, highest recoveries are achieved with CGA produced from the non-ionic surfactant, which indicates that, under these conditions, separation is driven mainly by hydrophobic interactions. In experiments with ethanolic/aqueous suspensions, when the hydrophobicity of the surfactant was increased by increasing volumes of SPAN 80, the CGA produced were less stable; thus higher recoveries of astaxanthin under conditions that favour hydrophobic interactions were not observed. (C) 2008 Elsevier B.V All rights reserved

Recovery of gallic acid with colloidal gas aphrons generated from a cationic surfactant

In a previous study we have demonstrated that gallic acid (GA) in its anionic form can be recovered from aqueous solutions using colloidal gas aphrons (CGA) generated from the cationic surfactant cetyltrimethylammonium bromide (CTAB). The aim of the present work is to get a better understanding of the separation mechanism in order to determine the optimum operating conditions to maximise the recovery of GA while preserving its antioxidant properties. Zeta potential measurements were carried out to characterise the surface charge of GA, CTAB and their mixtures at three different pH conditions (both in buffers and in aqueous solutions). GA interacted strongly with CTAB at pH higher than its pKa 3.14 where it is ionised and negatively charged. However, at pH higher than 7 GA becomes oxidised and loses its antioxidant power. GA recovery was mainly affected by pH, ionic strength, surfactant/GA molar ratio, mixing conditions and contact time. Scale-up of the separation using a flotation column resulted in both higher recovery and reproducibility. Preliminary experiments with grape marc extracts confirmed the potential application of this separation for the recovery of polyphenols from complex feedstock

Evaluation of sensory and in vitro anti-thrombotic properties of traditional Greek yogurts derived from different types of milk

Given that fermented dairy products exhibit high bioactivities against cardiovascular diseases (CVDs), the anti-thrombotic properties, fatty acid profiles and sensory properties of cow, goat and ewe derived Greek yogurts have been assessed and compared. The total lipids (TL), total polar lipids (TPL), total neutral lipids (TNL) were obtained and the polar lipid fractions were further separated by thin layer chromatography (TLC). These lipid samples (TL, TPL and TLC fractions) were subsequently assessed for their biological activity against atherosclerosis based on the in vitro inhibition of Platelet Activating Factor (PAF)-induced platelet aggregation. The fatty acid compositions of all yogurts were analyzed by Gas Chromatography with flame ionization detector (GC-FID). Goat yogurt lipids have been found to exert more potent inhibitory activity (i.e. lower IC50 values in both TL and TPL samples) in contrast to the corresponding fractions of cow and ewe yogurts. The observed sensory data indicates that ewe yogurt was the most palatable of all three Greek yogurts. © 201

Innovative milk and whey protein hydrolysates

Generation of bioactive compounds from milk proteins is a possible way to obtain bioactive peptide ingredients having a health promoting activity in cardiovascular disease, inflammation and cancer. These peptide sequences are inactive in the native protein but can be released during digestion or produced during in vitro enzymatic hydrolysis. Industrial-scale production of bioactive compounds from food protein hydrolysis has contributed to the appearance on the market of commercial products with milk bioactive peptides. The aim of this study was to investigate an efficient way to produce milk protein hydrolysates from different substrates: milk protein concentrate, whey protein concentrate and sodium caseinate. These substrates were hydrolysed with two enzyme preparations at 50\ub0C for 1 and 4 h at constant pH 7. Molecular mass distribution (by GPC), particle size (by laser light scattering analysis), degree of hydrolysis, turbidity and viscosity profiles of the hydrolysates, were evaluated. Both the used enzymes reached a hydrolysis degree up to 7% in all three substrates already after 1h with some differences in the 4h treatment. One enzyme showed best performance after 4h-treatment reaching 18% of hydrolysis with sodium caseinate. Particle size analysis suggested that the hydrolysed sodium caseinate can produce aggregates: this agrees with the turbidity test showing an absorbance increase at 550nm after hydrolysis, while in the other substrate it decreased. Viscosity decreased in all samples: according with GPC, after 1h incubation, more than 25% of the particles have a molecular mass below 1 kDa. Results showed a correlation between hydrolysis degree and molecular mass distribution, which is important for a possible influence of the hydrolysates addition as food ingredients. Additional studies were carried out to evaluate the effect of freeze and spray-drying on the viscosity and antioxidant properties of the hydrolysate and their incorporation into biscuits