Assessing the effect of Maillard reaction with dextran on the techno-functional properties of collagen-based peptides obtained from bovine hides

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Bovine hides, produced during the slaughter process, account for around 7% of the animal Alcalase. In present work, this fact was further confirmed since the techno-functional 49 properties of hides' hydrolysate (solubility, emulsifying ability, foam capacity and water and 50 oil holding capacity) were characterised and the results were very poor when compared to 51 intact collagen or gelatine. This loss of functionality will negatively impact the range of 52 application of the hydrolysates as food ingredient. 53 A possible way to enhance the hydrolysate techno-functional properties is by means of 54 controlled glycation following Maillard's reaction; which is a procedure that involves food 55 grade reagents and can be safely used for food industries with minimal changes to colour and 56 flavour when carried out under controlled reaction conditions (time, temperature and pH) 57 hence preventing progression to more advanced stages (

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In order to confirm the amount of peptides shorter than 3 kDa in the hydrolysates, these  Garden city, Herts, UK) fitted with a Jeol Na+ high performance cation exchange column.

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Norleucine was employed as internal standard. 126 To calculate the FAG as meq of leucine/g of sample (meq/g) a method with slight   170 The method of Coffmann and Garcia (1977) was followed with slight modifications.

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Aqueous solutions from 20 to 120 g/L of freeze-dried samples were adjusted to pH=6 using 1 172 mol/L NaOH or HCl; the solutions were heated in a thermostatic bath at 85 ºC for 30 min.   where Ve is the volume of the emulsified oil (mL) and Va the volume of the added oil (mL).  Since no main differences were found in the functional properties, size distribution or amino 233 acid profile between both hydrolysates, the one generated at 1:2 ratio was selected for further 234 research, given the fact that water consumption is minimised.

Changes in free amino groups and molecular size 237
In all cases a significant decrease (p<0.05) in the number of FAG was observed, 238 demonstrating that the glycation reaction took place (Table 2). In the case of hydrolysate 1:2,  The SEC analysis is further evidence that the glycation reaction occurred since an increment 251 in the molecular weight of peptides was observed. Particularly, Figure 1 shows the example 252 of the hydrolysate 1:2 and the porcine commercial gelatines before and after the treatment.

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After the treatment, Figure 1 In the case of the hides hydrolysates no differences were observed after the treatment: 268 complete solubility was detected before and after the treatment within the pH range tested.

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In the case of the porcine gelatine, the solubility was increased (p<0.05) in all the pH range

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A significant (p<0.05) decrease in OHW and WHC (Table 3) Figure 3 illustrates the percentage 295 of foam formation and its stability in both bovine and porcine gelatines.

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In the case of the bovine gelatine, the foam capacity is not modified after glycation (p>0.05); 297 however, the stability at 45 minutes of analysis was negatively affected (p<0.05). In the case 298 of the porcine gelatines, glycation and the glycation after the hydrolysis also negatively 299 affected the foam capacity and stability (p<0.05) when compared to the control; however, 300 foam was more stable within each treatment. Similar negative results were obtained for the 301 hide hydrolysates, since no improvement was observed after Maillard reaction (Figure 3b).

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The same outcome was found out or by Corzo-Martínez, Sánchez, Moreno, Patino, and 303 Villamiel (2012) when β-lactoglobulin was conjugated with galactose. LGC values was reported for purified bovine blood proteins (Álvarez et al., 2012); where it 327 was reported that dextran incorporated to the protein impeded the protein-protein interaction, 328 hence increasing the protein concentration required to form a stable gel.            A B -Hides' peptides with low molecular weight (<6.5 kDa) have poor functionality -Hides' peptides were successfully conjugated with dextran of 10 kDa -The techno-functional properties of hides' peptides were not modified after glycation