Effect of processing treatments on the allergenicity of nuts and legumes: A meta-analysis

The effective food processing to reduce nuts and legumes allergenicity could not be easily and directly concluded from reading a few published reports. Therefore, we conducted a meta-analysis to investigate this issue. A literature search was conducted in eight electronic databases from January 2000 to June 11, 2021. The primary outcome of interest was the allergenicity of processed nuts or legumes determined by enzyme-linked immunosorbent assay from in vitro studies. Data with the standardized mean difference (SMD) of 95% confidence interval (CI) were pooled using a random-effect model by RevMan 5.4 software. Heterogeneity was assessed using Cochran's Q (P_Q ) and I² tests. The search strategy identified 18,793 articles. However, only 61 studies met the inclusion criteria and were included in this meta-analysis. There were 21 and 15 types of respective single and combined food processing treatments analyzed for their effects on reducing allergenicity. In single processing treatment, the extrusion and fermentation had the largest reduction in allergenicity, considering their SMD value, that is, -20.19 (95% CI: -22.22 to -18.17; the certainty of evidence: moderate) and -20.8 (95% CI: -24.10 to -17.50; the certainty of evidence: moderate), respectively. Whereas in the combination, the treatment of fermentation followed by proteolytic hydrolysis showed the most significant reduction (SMD: -53.34; 95% CI: -70.18 to -36.5) and the evidence quality of this treatment was considered moderate. In conclusion, these three food processing methods showed a desirable impact in reducing nuts or legumes allergenicity. PRACTICAL APPLICATION: Nuts and legumes play an essential role as protein sources in food consumption worldwide, but they usually contain allergens. Our study has investigated the food processing methods that effectively reduce their allergenicity by meta-analysis. The result gives valuable information for further laboratory investigation on allergens and can be used by food industries in providing foods from nuts and legumes with lower allergenicity.