Functional, textural, and sensory properties of milk protein concentrate-based supercritical fluid extrudates made with acid whey

Figures & data

Table 1. GAW composition (6% solids measured according to the method by Menchik and Moraru ^[18], 12% solids calculated according to concentration factor).

Component	6% solids	12% solids
Total solids (% w/w)	6.00 ± 0.22	12.00
Total sugars (% w/w)	3.84 ± 0.33	7.68
Lactose	3.29 ± 0.21	6.58
Crude protein (% w/w)	0.30 ± 0.12	0.60
Ash (mg/g)	0.67 ± 0.03	1.34
K	1.61 ± 0.03	3.22
Ca	1.23 ± 0.04	2.46
P	0.68 ± 0.01	1.36
Na	0.39 ± 0.02	0.78
Mg	0.10 ± 0.01	0.20
Cl	0.86 ± 0.09	1.72

Table 2. Dry feed formulations of sweet (F1) and savory (F2) extrudates.

	Feed formulations (% wet basis)
	F1 (sweet)	F2 (savory)
MPC (81.5% protein, wet basis)	60.0	60.0
Buttermilk powder	4.5	5.0
Distilled monoglyceride	0.0	1.0
Fruit and vegetable powders	Raspberry: 11.7; Apple: 6.8; Banana: 5.6; Beet: 2.0; Carrot: 1.9	Tomato: 7.5; Chickpea: 4.5; Carrot: 3.5
Seasoning powders	Citric acid: 2.0; Sugar: 5.0; Salt: 0.5	Jalapeño seasoning: 7.0; Salt: 3.0; Sugar: 2.5; Citric acid: 3.0; Nutritional yeast: 1.5; Garlic powder: 1.5

Table 3. Proximate nutritional composition of F1 and F2 formulations prior to extrusion.

	Feed formulations
Composition per 100 g	F1 (sweet)	F2 (savory)
Calories	355.41	322.67
Moisture (g)	3.62	3.28
Protein (g)	54.99	56.36
Carbohydrates (g)	30.34	17.56
Dietary fiber (g)	6.73	2.35
Total sugars (g)	16.87	9.65
Added sugars (g)	4.99	2.50
Total fat (g)	3.16	4.09
Saturated fat (g)	0.87	1.82
Monounsaturated fat (g)	0.16	0.16
Polyunsaturated fat (g)	0.37	0.18
Trans fat (g)	0	0
Cholesterol (mg)	3.11	3.45
Calcium (mg)	1656.45	1661.29
Iron (mg)	0.85	0.85
Phosphorous (mg)	85.47	75.45
Potassium (mg)	372.97	513.45
Sodium (mg)	304.16	1546.60
Vitamin D (mcg)	0.02	0.03
Vitamin A (IU)	2207.64	5605.20
Vitamin C (mg)	60.59	56.00

*Values are calculated according to the nutritional composition for MPC and fruit and vegetable powders provided by Ingredia and Van Drunen Farms. All other ingredient information was obtained from the USDA Food Composition Database.

Figure 1. Diagram of SCFX process.

Figure 2. Photographs of formulations F1 and F2, produced with (a) water; (b) unhydrolyzed GAW; (c) hydrolyzed GAW.

Table 4. Physical characteristics of formulations F1 and F2, produced with (a) water; (b) unhydrolyzed GAW; (c) hydrolyzed GAW. F1 is compared with multigrain cheerios (MGC) and F2 is compared with pita chips (PC) as commercial samples.

	F1A	F1B	F1C	MGC	F2A	F2B	F2C	PC
Cell size (μm)	299.20±158.90^a	533.03±264.41^b	479.20±249.37^b	NA	450.20±206.43^a	577.50±322.28^ab	637.47±276.86^b	NA
Color
L* value	52.83±2.43^a	57.91±3.25^a	58.26±3.54^a	NA	70.27±0.41^a	68.69±2.91^a	68.45±0.64^a	NA
Whiteness Index	50.61±1.55^a	51.74±2.52^a	52.45±3.61^a	NA	47.87±1.31^a	44.18±3.26^b	43.61±0.84^b	NA
Texture
Hardness (N)	270.69±56.99^a	138.07±21.21^b	184.22±19.50^c	105.9±16.5^b	115.07±34.86^a	97.59±24.20^a	92.47±26.17^a	118.63±101.05^a
Crispness (no. of peaks)	15.15±4.66^ab	17.80±6.65^b	23.10±8.19^c	10.60±3.75^a	25.16±9.53^a	21.35±12.90^a	21.25±11.35^ab	10.40±3.75^b
Crunchiness (N)	15.44±3.96^a	11.86±3.01^b	13.56±3.05^ab	6.30±2.68^c	10.21±2.05^a	10.69±3.04^a	9.55±2.74^a	7.83±5.93^a

*Means in the same group and row with different superscripts are significantly different (P < 0.05). All values are shown ±1 standard deviation. NA = Not Applicable.

Figure 3. Expansion characteristics in formulations F1 and F2: (a) Radial expansion ratio; (b) piece density; and (c) porosity (± 1 SD) produced with water, unhydrolyzed GAW, and hydrolyzed GAW. Means with different letters are significantly different (P < .05).

Figure 4. SEM photos of cross-sectioned extrudates produced with (a) water; (b) unhydrolyzed GAW; (c) hydrolyzed GAW.

Table 5. Sensory evaluation results of formulation F1 with three liquid sources, rated on a 9-point hedonic scale.

Sensory attributes	Liquid source
	A (Water)	B (Unhydrolyzed GAW)	C (Hydrolyzed GAW)
Appearance	5.43^a	6.11^b	5.92^b
Color	5.94^a	6.07^a	6.17^a
Shape	5.27^a	6.16^b	5.99^b
Flavor	4.43^a	4.77^ab	5.14^b
Texture	4.66^a	5.28^b	5.36^b
Overall	4.19^a	4.97^b	5.02^b

*Means in the same row with different letters are significantly different (P < 0.05).

Figure 5. JAR results from consumer acceptance test for F1 extrudates produced with (a) water; (b) unhydrolyzed GAW; (c) hydrolyzed GAW.

Menchik, P.; Moraru, C. I. Nonthermal Concentration of Liquid Foods by A Combination of Reverse Osmosis and Forward Osmosis. Acid Whey: A Case Study. J. Food Eng. 2019, 253, 40–48. DOI: 10.1016/j.jfoodeng.2019.02.01.

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