Fish gelatin (FG) has been modified to replace mammalian gelatin, but has not been applied in the yogurt production. In this study, xanthan gum (XG) was used to improve the rheology properties of FG, and the XG- modified FG was applied in acid milk gels and low-fat yogurts to mimic the rheology and texture properties of porcine gelatin (PG). No obvious difference in the storage moduli was observed for the FG gels (2.5 g/100 g) with the addition of XG from 0 to 0.05 g/100 g, while increasing addition of XG increasingly impeded the gelation process of FG. Moreover, in the milk gel system with FG addition (0.4 g/100 g), an increase in the XG proportion caused an increase in the storage moduli. Milk gels with a XG to FG ratio of 1:99 best mimicked the storage moduli of milk gels with PG. In the yogurt system, yogurt with 0.4 g/100 g XG-modified FG had better water-holding capacity and consistency than the yogurt with 0.4 g/100 g PG, and had similar viscosity, pseu- doplasticity, and thixotropy to yogurt with 0.4 g/100 g PG. The results suggested that XG-modified FG is a promising replacement for mammalian gelatin in low-fat stirred yogurt.

Microbial, physicochemical, rheological, and microstructural changes of surimi prepared by pH shift methods and the traditional water-washing method during cold storage were investigated. The starting aerobic mesophilic count (AMC) of pH shift surimi was around 1 log CFU/g lower than water-washed surimi, suggesting antimi- crobial effects of the pH shift. All samples could be stored for 5 to 6 days based on the AMC results. Throughout count (AMC) of pH shift surimi was around 1 log CFU/g lower than water-washed surimi, suggesting antimi- crobial effects of the pH shift. All samples could be stored for 5 to 6 days based on the AMC results. Throughout the storage, the gel strength of alkaline-treated surimi increased from 204.2 to 491.9 g, while water-washed surimi decreased from 462.1 to 172.9 g. After the storage, alkaline-treated surimi showed lower total volatile basic nitrogen (TVB-N) value and smaller network hole size that was suitable for incorporation of moisture and starch. It also remained its rheological properties comparing with acid-treated surimi, with better odour prop- erties, less protein degradation, and better network formation. The results indicate that alkaline-treated surimi is more suitable for cold storage.

In this study, two near neutral pH electrolyzed water (NEW1 produced by redirecting of the catholyte solution back to the anode chamber and NEW2 produced by NaCl and NaHCO3 as electrolyte) and control (NEW0, produced by commercial unit) were evaluated for their stability during 75 hr storage at 7°C. The physicochemical properties, bactericidal efficiencies, and sanitizing effects on organic fresh-cut lettuce of them were compared. The results showed that NEW2 was more stable than NEW1 and NEW0 during storage. The free available chlorine of it increased by approximately 35% after the storage. And, all three NEWs showed decreased bactericidal effects compared with that before the storage. In addition, all of them were effective against Escherichia coli and Listeria innocua Seeliger inoculated on organic fresh-cut lettuce, with 1.19–1.40 and 0.92–1.21 log CFU/g reductions, respectively. In terms of physicochemical parameters, there were no significant differences among different treatments.

Tea water-insoluble protein nanoparticles (TWIPNs) can be used as Pickering particles. However, Pickering emulsions stabilized by heat-treated TWIPNs (TWIPNPEs) were not characterized clearly. Therefore, the effect of heat-treated TWIPNs on the characteristics of Pickering emulsions was analyzed. TWIPNs became small at 60 ​ ◦ C and reassembled at 100 and 120 ​ ◦ C. Disulfide bonds and noncovalent bonds synergistically participated in the intermolecular forces of heat-treated TWIPNs. The random coil content of heat-treated TWIPNs decreased from 0.24 to 0.13 and the contents of α -helices and β-sheets increased from 0.11 to 0.27 to 0.19 and 0.30 in the proportion of secondary structure with the increase in heat-treated TWIPN temperature. High temperature (100 ​ ◦ C/120 ​ ◦ C) on TWIPN accelerated the flocculation of emulsion droplets. A potential mechanism for the changes occurring in TWIPNPEs based on heat-treated TWIPNs was proposed to exhibit the instability of TWIPNPEs stabilized by heat-treated TWIPNs due to the structural rearrangements and enhanced intermolecular forces of TWIPNs at 100 and 120 ​ ◦ C. Besides, heat-treated TWIPNs at 30 and 40 ​ g/L decreased the gel-like behavior of TWIPNPEs. These results can broaden our understanding of the characteristics of TWIPNPEs stabi- lized by heat-treated TWIPNs for utilizing tea by-products.

Heavy metals accumulating in the human body produce physiological toxi- city by interfering with the transport of human proteins and enzymes. Heavy metals detection is significant for food safety assurance. This review focuses on recent advances of heavy metals detection of food and agricultural products by surface-enhanced Raman spectroscopy (SERS). The article covers the SERS basic principles and advances in heavy metals detection, including mercury, arsenic, cadmium, lead, chromium among others. Insights in the potential of combining chemometrics and multivariate analysis with SERS and the exploration of novel SERS substrate platforms from both macro and micro scale are discussed. Finally, future application of SERS in heavy metal detection are prospected. SERS is a powerful and promising technique offering the advantages of simple sampling, rapid data collection and non- invasiveness. The findings of this study can allow better understanding of the heavy metals’ occurrence and the possibility of its detection using SERS.

Lipid and protein oxidation in catfish (Clarias lazera) surimi during proces- sing and storage were assessed. Catfish surimi were washed in deionized water: M0 (no washing step), M1 (one washing step), and M2 (two washing steps). Lipid, protein, water, and iron contents were determined. M0, M1, and M2 were stored for 0, 1, 4, 7, or 10 days at 4 ± 1°C; at each time point, samples were removed for analyses. Lipid oxidation was assessed by mea- suring malondialdehyde content. Protein oxidation was assessed by mea- suring protein solubility and protein sulfhydryl and carbonyl group contents. Based on the results, lipid content, L* and a* (color parameters), and fatty acid content in M1 and M2 were significantly reduced. Lipid oxidation development was faster in M1, and the ranking was as follows: M1 > M2 > M0, with M0 being significantly less oxidized than M1. Increasing the number of washes increased protein oxidation, and the ranking was follows: M2 > M1 > M0. Altogether, lipid and protein oxidation and physicochemical changes occurred simultaneously to different degrees in surimi during various processing and storage conditions.

Potential organic compatible sanitisers including electrolysed water (EW, 4 mg/L free available chlorine (FAC)), citric acid (0.6%), H 2 O 2 (1%), and their combinations were applied on organic and conventional fresh-cut lettuce ( Lactuca sativa Var crispa L.) to evaluate their effects on microbiological safety, physicochemical parameters and sensory analysis (including raw sample and boiled sample). The combination of 1% H 2 O 2 with 0.6% citric acid led to the highest reductions of microbial loads (2.26 log CFU/g for aerobic mesophilic count (AMC) and 1.28 log CFU/g for yeasts and moulds); however, it also caused the highest electrolyte leakage rate (3.11% vs. 0.91% for control). The combination of EW with 1% H 2 O 2 achieved 1.69 and 0.96 log CFU/g reductions for AMC and yeasts and moulds, respectively with electrolyte leakage rate of 1.41%. In terms of the content of polyphenolic compounds, firmness, colour and raw material sensory analysis, there were no significant differences among different treatments, and between organic and conventional counterparts. The results suggest that 1% H 2 O 2 combined with 4 mg/L EW is a promising approach for treating organic fresh-cut lettuce.

The sanitising effect of low concentration neutralised electrolysed water (LCNEW, pH: 7.0, free available chlorine (FAC): 4 mg/L) combined with ultrasound (37 kHz, 80 W) on food contact surface was evaluated. Stainless steel coupon was chosen as attachment surface for Escherichia coli ATCC 25922, Pichia pastoris GS115 and Aureobasidium pullulans 2012, representing bacteria, yeast and mold, respectively. The results showed that although LCNEW itself could effectively reduce survival population of E. coli ATCC 25922, P. pastoris GS115 and low concentration A. pullulans 2012 in planktonic status, LCNEW combined with ultrasound showed more sanitising efficacy for air-dried cells on coupons, with swift drops: 2.2 and 3.1 log CFU/coupon reductions within 0.2 min for E. coli ATCC 25922 and P. pastoris GS115, respectively and 1.0 log CFU/coupon reductions within 0.1 min for A. pullulans 2012. Air-dried cells after treatment were studied by atomic force microscopy (AFM)/optical microscopy (OM) and protein leakage analyses further. All three strains showed visible cell damage after LCNEW and LCNEW combined with ultrasound treatment and 1.41 and 1.73 μg/mL of protein leakage were observed for E. coli ATCC 25922 and P. pastoris GS115, respectively after 3 min combination treatment, while 6.22 μg/mL of protein leakage for A. pullulans 2012 after 2 min combination treatment. For biofilms, LCNEW combined with ultrasound also significantly reduced the survival cells both on coupons and in suspension for all three strains. The results suggest that LCNEW combined with ultrasound is a promising approach to sanitise food equipment.

The effects of rice bran wax coating on the physicochemical properties such as firmness, weight loss, titratable acidity (TA) and soluble solid content (SSC) of cherry tomatoes were studied during cold storage. The chemical and nanostructure properties of chelate-soluble pectin (CSP) were also investigated by high-performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). The results indicated that there was no significant difference of firmness between control (2.48 N) and waxed (2.87 N) fruits at the end of storage (20 days), while the weight loss of waxed fruits (13.54%) was lower than that of control fruits (16.02%). And the degree of esterification (DE) of both fruits decreased after cold storage by FTIR. The structural analysis by atomic force microscopy (AFM) indicated that rice bran wax coating inhibited the degradation of CSP. The CSP molecular widths ranged from 15 to 250 nm, and the vertical heights varied from 0.2 to 2.0 nm. Greater frequency ( F q ) of large width and length CSP was found in waxed fruits than in control fruits. The results suggest that rice bran wax coating was an effective way to preserve fresh fruits.

The effects of low-concentration electrolysed water (LcEW) (4 mg/L free available chlorine) combined with mild heat on the safety and quality of fresh organic broccoli ( Brassica oleracea ) were evaluated. Treatment with LcEW combined with mild heat (50 °C) achieved the highest reduction in naturally occurring microorganisms and pathogens, including inoculated Escherichia coli O157:H7 and Listeria monocytogenes ( P < 0.05). In terms of the antioxidant content of the treated broccoli, the total phenolic levels and ferric reducing antioxidant power remained unchanged; however, the oxygen radical absorbance capacity of the treated broccoli was higher than that of the untreated control. In addition, mild heat treatment resulted in an increase in firmness. The increased firmness was attributed to changes in the pectin structure, including the assembly and dynamics of pectin. The results revealed that mild heat induced an antiparallel orientation and spontaneous aggregation of the pectin chains. This study demonstrated that LcEW combined with mild heat treatment was effective to reduce microbial counts on fresh organic broccoli without compromising the product quality.