Monitoring hydroperoxides formation as a measure of predicting walnut oxidative stability

It is believed that lipids are the most important factor affecting nuts shelf-life. In the present study, an accelerated shelf-life testing by means of elevated temperatures 62, 72, and 82 °C was conducted to predict the oxidation stability of walnuts over a long-term storage. Peroxide value (PV) was employed to monitor the lipid oxidation progression in the walnuts. A range of 74.01–79.57 kJ mol−1 K−1 energy was required for formation of primary oxidation products. The reaction changes followed an apparent first-order kinetic. Formation of hydroperoxides in walnut kernels was found to be a temperature-dependent reaction with Q10 of 2.1. Walnut kernels were also kept in normal condition (temp: 20–30 °C; relative humidity (RH): 35–45%) for 12 months to validate the shelf-life estimation approach. The results showed that PV could provide a proper estimation for oxidative stability of the walnuts stored in ordinary condition

Evaluation of antimicrobial and probiotic properties of the predominant LAB isolated from fermented germinated clover seed رز�اب� خص�ص�ات ضد٠�کر�ب� � پر�ب��ت�ک� باکتر� اس�د �اکت�ک غا�ب جدا شد� از تخ٠�ر تصاد��

Recently, the tendency to use probiotic-potential starter cultures among lactic acid bacteria (LAB) isolated from non-dairy fermented substrates has been increased. The aim of this study was to isolate and molecularly identify the predominant LAB isolated from fermented germinated clover seeds, and also to evaluate its probiotic and antifungal properties. The LAB isolate was identified asPediococcus pentosaceus, in accordance with the sequencing results of the PCR products. The antifungal and antibacterial effect of the isolate on Aspergillus niger and Staphylococcus aureus was significantly (P <0.05) higher than the other studied foodborne fungi and bacteria. Furthermore, P. pentosaceus isolate had a good survival (77.22) in simulated gastrointestinal conditions. The isolate had no hemolytic activity, and its auto-aggregation activity was 35.51. Also, the rate of co-aggregation of the isolate with Escherichia coli and S. enterica was equal to 48.71 and 18.43, respectively. In addition, the bacterium was sensitive to the penicillin, cephalothin, ampicillin and cefazolin antibiotics. Accordingly, it is possible to use the isolate as a probiotic culture with potential biological preservative in the food industry. © 2022 Journal of Food Science and Technology (Iran). All rights reserved

Physicochemical, antioxidant, calcium binding, and angiotensin converting enzyme inhibitory properties of hydrolyzed tomato seed proteins

The objective of this was to determine the impact of enzymatic hydrolysis on the multifunctionality of tomato seed protein hydrolysates (TSPH) and their physicochemical properties. The enzymatic hydrolysis was performed using alcalase and two factors response surface methodology. The best conditions were 131.4 min and 3% enzyme/substrate (E/S) for antioxidant activity; 174.5 min and 2.93% E/S for angiotensin-converting enzyme (ACE) inhibition; and 66.79 min and 2.27% E/S for the calcium binding. Antioxidant and ACE hydrolysates were characterized by higher solubility, zeta potential, and thermal stability while properties of the calcium binding hydrolysate were only minimally affected by the enzymatic hydrolysis. Gel electrophoresis showed that molecular weights of polypeptides in the calcium binding TSPH were higher compared to those in ACE and antioxidant TSPHs. This was due to the low degree of hydrolysis of the calcium binding hydrolysate. Practical applications: Nowadays, different protein sources are used to produce protein hydrolysates containing bioactive peptides that can help alleviate oxidation of foods, oxidative stress, and chronic conditions (e.g., hypertension, diabetes, cardiovascular disorder). Hydrolyzed proteins also have the potential to increase mineral absorption through the formation of mineral-binding complexes.