Separation of α-Lactalbumin Enriched Fraction from Bovine Native Whey Concentrate by Combining Membrane and High-Pressure Processing

Abstract

Whey exhibits interesting nutritional properties, but its high β-Lactoglobulin (β-Lg) content could be a concern in infant food applications. In this study, high-pressure processing (HPP) was assessed as a β-Lg removal strategy to generate an enriched α-Lactalbumin (α-La) fraction from bovine native whey concentrate. Different HPP treatment parameters were considered: initial pH (physiological and acidified), sample temperature (7–35 °C), pressure (0–600 MPa) and processing time (0–490 s). The conditions providing the best α-La yield and α-La purification degree balance (46.16% and 80.21%, respectively) were 4 min (600 MPa, 23 °C), despite the significant decrease of the surface hydrophobicity and the total thiol content indexes in the α-La-enriched fraction. Under our working conditions, the general effects of HPP on α-La and β-Lg agreed with results reported in other studies of cow milk or whey. Notwithstanding, our results also indicated that the use of native whey concentrate could improve the β-Lg precipitation degree and the α-La purification degree, in comparison to raw milk or whey. Future studies should include further characterization of the α-La-enriched fraction and the implementation of membrane concentration and HPP treatment to valorize cheese whey.

Separation of α-Lactalbumin-Enriched Fractions from Caprine and Ovine Native Whey Concentrate by Combining Membrane and High-Pressure Processing

“…Samples (50 mL), equilibrated at room temperature, were transferred in high-density polyethylene (HDPE) bottles (Nalgene, Thermo Fisher Scientific Inc., Whaltham, MA, USA) for HPP processing. HPP processing was carried out at 600 MPa for 2, 4, and 15 min at room temperature (23 • C), in agreement with the results observed in NWC from cow [35], with n = 3 independent treatments for each of the two NWCs. Untreated samples for both pH conditions were used as controls.…”

“…The effect of high-pressure processing (HPP) on ovine and caprine NWC at physiological and acidified pH was studied by applying process conditions (600 MPa and 23 • C), which provided the best balance between α-La yield and purification degree in previous works with bovine whey [34,35].…”

“…One lot of raw skimmed goat milk and one lot of raw sheep milk (500 L each) were supplied by local farms. Raw milk was microfiltered and ultrafiltered following the same protocol as in Romo et al [35], using a SW40 MMS AG and a SW18 filter systems (MMS AG Membrane Systems, Urdof, Switzerland) according to Figure 1. When the native whey was obtained and concentrated, sodium azide (0.33%) was added and stored at 4 • C for 12 h until the high-pressure processing treatment (HPP) was complete.…”

“…Samples (50 mL), equilibrated at room temperature, were transferred in high-density polyethylene The main compositional parameters of the resulting native whey concentrates (NWCs) are summarized in Table 1. Fat content (% w/w), protein content (%), total dry matter, and ash (% w/w) were determined according to Romo et al [35], following the protocols ISO 1211/IDF1 [36], ISO 8968-3/IDF20-3 [37], ISO 2920:2004/IDF58:2004 [38], and BOE-A-1977-16116 [39], respectively. Lactose was estimated by subtracting the total fat, total protein, and ash from the total dry matter, while pH was determined with a pH-meter (sensION+ PH3, HACH Co., Loveland, CO, USA).…”

“…Likewise, in ovine milk, Huppertz et al [30], Moatsou et al [31], and Sakkas et al [32] noted that α-La was denatured at pressures higher than 600-650 MPa, while β-Lg started to be affected from 200 MPa. Although fractionation of α-La-enriched fractions from bovine whey by HPP have been described in some papers [25,[33][34][35], to the best of our knowledge, there is still a lack of studies focused on the HPP of ovine and caprine concentrated native whey to obtain α-La-enriched fractions.…”