5.1.1.4 Soy milk
The nutritious nature of soymilk makes it prone to microbial attack as the nutrients it contains are also required for the growth of most spoilage organisms if not properly processed and stored. A large number of microorganisms such as coliforms, mesophilic aerobic bacteria, yeasts and moulds are responsible for the spoilage of soymilk and it can produce undesirable changes in the milk. Fresh soymilk is of high susceptibility to spoilage microorganisms such as Klebsiella spp. and Serratia spp.. The shelf life of the unsterilized fresh soymilk is rather short, even just 1 day in summer. 
 
NisinZ® or Proteria™ DV combined with heating treatment not only preserve soymilk up to 13 days but also increase the color, flavor, taste and overall acceptability of soymilk.
 
Handary Shelf-life Solutions for Soymilk
Applications
Shelf-life diagnostics
Products
Labelled as
Dosage
Approved countries
Clean-label
5.1.1.2 Soymilk
Gram-positive bacteria
NisinZ®
Nisin
25-100mg/kg
China
Medium
Total plate count
Proteria™ DV
Vinegar
5-10g/kg
China, EU, USA
Medium

 

NATURAL PROTECTIVE SOLUTIONS
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Proteria® DV Reduces Total Plate Count in soymilk
NisinZ®- Reduces Total Plate Count in soy milk
Soy milk is abundant in nutrients, canned soy milk can be preserved for a long time after being sterilized by autoclaving. Because of low cost, autoclaving (121 °C, 20 min) is adopted by many SME manufacturers, however, because of the heating process, the color and flavor of soy milk may deteriorate and some of the nutrients may be damaged. For example, fat may separate out, and protein may flocculate and precipitate. Adding NisinZ® in soybean milk may reduce the time of sterilization, improve its quality and extend shelf life.
 
The concentration of dissolved solids in canned soy milk was 6%, with NisinZ® at 100mg/kg. The temperature of sterilization was 121 °C, but the process time was shortened from 15 min to 7 min. after sterilization, the samples were stored at 37 °C and 55 °C respectively. The results showed that 15% of the control samples without NisinZ® were spoiled after 7 days, and 65% after 23 days. Total spoilage rate was 80%. At 55 °C, 90% of the control samples were spoiled after 23 days. However, under the same conditions, none of the test sample with NisinZ® was spoiled.
 
Another experimental case showed that the shelf life of packed soy bean milk extended from 4-10 days at 5-8 °C, with the addition of 100mg/kg NisinZ®. When boiled, the soy milk maintained full flavor and no sediment was observed.
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