Supplementary file 1_Nisin improves the storage quality of refrigerated pre-packaged fermented soybean whey-tofu—food safety, texture, and flavor.docx

IntroductionFermented soybean whey-based tofu, a traditional and popular food product, faces significant spoilage issues during storage, including texture softening, elevated volatile basic nitrogen (TVB-N) levels, and accumulation of biogenic amines, which can compromise sensory attributes and pose health risks. Current preservation strategies, such as physical sterilization and chemical preservatives, have limitations due to potential nutritional loss and safety concerns. Therefore, there is an urgent need for safe, efficient, and eco-friendly preservation technologies. This study evaluates the potential of nisin, a natural bacteriocin, as a preservative for fermented soybean whey-based tofu.
MethodsFermented soybean whey-based tofu was treated with different concentrations of nisin (0, 0.5, 1, and 2%) and stored at 10 °C for 28 days. The effects of nisin on physicochemical properties, biogenic amine accumulation, sensory attributes, and volatile flavor profiles were assessed.
ResultsNisin significantly inhibited microbial growth, reduced biogenic amine accumulation (histamine and tyramine) by 40–60%, and maintained water-holding capacity and sensory scores. The 2.0% nisin treatment showed the best preservation effect, but 1.0% was deemed most suitable considering market acceptance and cost. Nisin also suppressed off-flavor compounds while retaining key aroma contributors, as confirmed by electronic nose and gas chromatography–ion mobility spectrometry (GC–IMS)/gas chromatography–mass spectrometry (GC–MS) analyses.
ConclusionOverall, nisin effectively enhanced the storage quality and shelf life of fermented soybean whey-based tofu through multidimensional mechanisms, offering a natural preservation strategy for traditional soy products.