The Impact of Lactic Acid Bacteria on Rheological Properties of Whey-Pectin-Based Edible Coatings

Edible coatings made from dairy by-products have recently become a popular method for incorporating beneficial components, such as probiotics, into food products. However, there is a lack of understanding of how the incorporation of lactic acid bacteria (LAB) effects the rheological properties of whey-pectin-based edible coatings.

In this research, two edible coatings composed of either liquid acid whey protein concentrate (LAWPC) or liquid acid whey permeate (LAWP) were supplemented with Lacticaseibacillus paracasei and Lactobacillus helveticus (approximately 7 log CFU/g). The rheological behavior of these coatings was evaluated using a rheometer (300 s⁻¹ of shear rate), tensiometer, and contact angle meter.

The results revealed that LAWP-based coatings showed the lowest viscosity (average of the samples—20.9 Pa), making them suitable for spraying on the food product' surface and covering it, while the most viscous sample was the LAWPC-based control (44.2 Pa) coating (p < 0.05). This outcome was influenced by the higher solids content of the LAWPC-based coating, making it suitable for product immersion. Notably, the addition of LAB significantly decreased the viscosity of the LAWPC-based samples with encapsulated bacteria (with added L. paracasei—30.6 Pa; with added L. helveticus—27.3 Pa) (p < 0.05). However, the results showed that there were no statistical differences (p > 0.05) between samples in the case of surface tension and contact angle measurement results.

Overall, the rheological properties of the coatings, particularly viscosity, varied among the samples and were influenced by the presence of LAB and the different solid content of LAWP and LAWPC. Despite these variations, the base and LAB did not affect the surface tension and contact angle results. These findings provide valuable information for determining the most suitable technique for applying the coating to product surfaces and highlight the potential of LAB-incorporated edible coatings for delivering probiotics.