Wheat Protein Hydrolysates Improving the Stability of Purple Sweet Potato Anthocyanins under Neutral pH after Commercial Sterilization at 121 °C.

Anthocyanins are prone to degradation and color fading after sterilization. This work examined the potential of wheat protein hydrolysates (WPHs, 40 g/L) in improving the stability of purple sweet potato anthocyanins (PSPAs) under a pH of 6.8 after sterilization at 121 °C followed by storage. Results showed that WPHs increased the thermal degradation half-life of PSPAs 1.65 times after sterilization. Compared to PSPAs alone, after being stored at 37 °C and 45 °C for 7 days, the retention concentration of PSPAs with WPHs was 5.4 and 32.2 times higher, and the color change of PSPAs with WPHs decreased from 6.19 and 10.46 to 0.29 and 0.77, respectively. AFM data, fluorescence and UV spectrograms indicated the formation of complexes between PSPAs and WPHs by hydrophobic attraction confirmed by zeta-potential data. PSPAs with WPHs had stable particle size and zeta potential, which may also significantly increase the concentrations after digestion and antioxidant power of PSPAs. This work indicated that the assembled PSPAs composite structure by WPHs significantly reduced the degradation of PSPAs at a pH of 6.8 after sterilization at 121 °C followed by long-term storage.

The alleviative effect of curdlan on the quality deterioration of konjac glucomannan thermo-irreversible gels after commercial sterilization at 121 °C.

This work employed different curdlan concentrations (0.00 %, 1.00 %, 1.50 %, 2.00 %, and 2.50 %) to alleviate the quality degradation of konjac glucomannan (KGM) gels after commercial sterilization at 121 °C for 15 min. The results showed that all levels of curdlan could retard the deterioration of KGM gels, with the best effect at 2.00 %. After commercial sterilization, incorporating curdlan into KGM gels greatly reduced the Tan σ (G"/ G'), total relaxation time and half-free water from 0.52, 89.85 ms and 98.26 % to 0.27, 38.48 ms and 21.42 %, respectively. Moreover, the addition of curdlan imparted a better texture to KGM gels, as reflected in the increase of hardness, springiness, water-holding capacity and whiteness value from 1400.85 g, 0.42, 87.92 % and 33.33 to 3461.68 g, 0.80, 96.50 % and 49.27, respectively. Furthermore, SEM images revealed that curdlan endowed KGM gels with a tighter structure and smaller pores, and the pore size distribution was reduced from 113.46 µm to17.91 µm, indicating a stronger interaction among molecules, as evidenced by XRD and FTIR results. KGM gels with curdlan possessed less proportion of complete crystallites and crystalline region. These findings suggested that curdlan can be the potently protectant for improving the quality of commercially sterilized KGM gel-based products.

The effect of different tea products on flavor, texture, antioxidant and in vitro digestion properties of fresh instant rice after commercial sterilization at 121 °C.

The conventional process of commercial sterilization at 121 °C resulted in undesirable flavor, injured texture and fast starch digestion of fresh instant rice (FIR) with non-dehydration. In this study, tea products, such as instant green tea (IGT), instant black tea (IBT) and matcha (Mat) were chosen as ingredients to improve the quality of FIR. The results showed thatadding tea products endowed FIR with subtle flavors and higher antioxidant capacity. And the data of XRD, FTIR and SEM indicated that the improved texture of FIR with suitable chewiness was attributed to the stability of non-crystal structure. Furthermore, compared with IBT and Mat, IGT increased the ability against digestion from 10.18% to 30.44% and delayed the retrogradation rate from 18.89% to 4.38% evidenced by T2 values after stored for 14 d. Therefore, adding tea products will be a new way to improve the quality of FIR.

Bacteria and Bioactivity in Holder Pasteurized and Shelf-Stable Human Milk Products.

Background: Historically, Holder pasteurization has been used to pasteurize donor human milk available in a hospital setting. There is extensive research that provides an overview of the impact of Holder pasteurization on bioactive components of human milk. A shelf-stable (SS) human milk product, created using retort processing, recently became available; however, to our knowledge, little has been published about the effect of retort processing on human milk. Objective: We aimed to assess the ability of retort processing to eliminate bacteria and to quantify the difference in lysozyme and secretory immunoglobulin A (sIgA) activity between Holder pasteurized (HP) and SS human milk. Methods: Milk samples from 60 mothers were pooled. From this pool, 36 samples were taken: 12 samples were kept raw, 12 samples were HP, and 12 samples were retort processed to create an SS product. All samples were analyzed for total aerobic bacteria, coliform bacteria, Bacillus cereus, sIgA activity, and lysozyme activity. Raw samples served as the control. Results: One raw sample and 3 HP samples contained B. cereus at the time of culture. There were no detectable bacteria in SS samples at the time of culture. Raw samples had significantly greater lysozyme and sIgA activity than HP and SS samples (P < 0.0001). HP samples retained significantly more lysozyme and sIgA activity (54% and 87%, respectively) than SS samples (0% and 11%, respectively). Conclusions: Human milk processed using Holder pasteurization should continue to be screened for the presence of B. cereus. Clinicians should be aware of the differences in the retention of lysozyme and sIgA activity in HP and SS products when making feeding decisions for medically fragile or immunocompromised infants to ensure that patients are receiving the maximum immune protection.