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Cryoprotective Effect of Vicia ervilia Seed Protein Isolate on the Viability of Lactobacillus acidophilus LA-5
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Vida Gholifar   , Reza Rezaei Mokarram , Mahmood Sowti Khiabani , Soheila Zarin ghalami * |
| Department of Food Science and Engineering, Faculty of Agriculture, University of Zanjan |
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Abstract: |
In this study, the cryoprotective potential of Vicia ervilia seed protein isolate (VSPI) at concentrations of 1, 5, and 10% was investigated for enhancing the viability of Lactobacillus acidophilus LA-5 during freeze-drying and subsequent storage for 42 days at 4 °C, using skim milk as the reference standard. Lyophilized formulations containing the bacteria and cryoprotective agents were first characterized structurally using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). FTIR spectra revealed the presence of active functional groups, including –OH, –NH₂, and amide bands, in both cryoprotective materials, suggesting their potential involvement in hydrogen bonding and cell membrane stabilization. XRD analysis demonstrated a predominantly amorphous structure in the VSPI, in contrast to the semi-crystalline nature of skim milk, which may afford greater protection against mechanical stress during the freezing process. Moreover, SEM micrographs showed a uniform, compact, and crack-free matrix in the VSPI, whereas the skim milk sample exhibited a brittle and fragmented morphology, further supporting the superior protective capacity of the VSPI. Viability assessments over the 42-day storage period indicated that the 10% VSPI sample maintained significantly higher survival of Lactobacillus acidophilus LA-5 (4 × 10⁷ CFU/mL) compared to skim milk (1.3 × 10⁶ CFU/mL) at the end of storage (P < 0.05). Collectively, these findings demonstrate that VSPI, particularly at a 10% concentration, functions as an effective, natural, and biocompatible cryoprotective agent and offers a promising alternative to conventional protectants such as skim milk for the preservation of probiotic cultures.
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| Keywords: Vicia ervilia protein isolate, freeze-drying, skim milk, Lactobacillus acidophilus LA-5, cryoprotection |
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Type of Study: Research |
Subject:
General
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