Low-field nuclear magnetic resonance for online determination of water content during sausage fermentation

Phase behavior of the gelation process of myofibrillar protein-curdlan blended system: Discussion based on rheology and gel properties

The phase behavior in protein-polysaccharide blended systems is the main factor affecting the physical properties of composite gels; however, the phase behavior at room temperature and during heated gelation is lacking discussion. In this research, extracted grouper myofibrillar protein (MP) and curdlan (CUR) were used as models for the MP-CUR blended system. The phase behavior of the MP-CUR blended system was analyzed using rheology and microstructure analysis, and the accuracy of the phase behavior analysis was verified by measuring the physical indices such as gel properties of the MP-CUR composite gels. At room temperature, MP and CUR showed good co-solubility, so the blended system with 0.8% CUR content obtained the best apparent viscosity, structural recoverability, and other rheological properties. After heating gelation, MP and CUR had strong thermodynamic unaffinity leading to phase separation, and the best storage modulus was obtained for the MP-CUR blended system with 0.6% CUR content. Therefore, it is concluded that 0.6% CUR content is the critical concentration for the MP-CUR blended system. The results were also confirmed by the best gel properties of 0.6% CUR composite gel when the physical properties of the composite gel were determined. The phase behavior evaluation was used to determine the appropriate polysaccharide concentrations as a means to improve the physicochemical properties of the composite gels and to exploit the value of polysaccharides in protein-based food applications.

Storage Stability of Meat Analogs Supplemented with Vegetable Oils

The addition of various oils to meat analog has been an important topic to improving its juiciness and tenderness. However, this causes a concern about oil leaching from the meat analog during long-term storage. Here, we aimed to assess the storage stability of vegetable-oil-supplemented meat analogs and analyze the effects of temperature and storage period on their physiochemical characteristics. The meat analogs were prepared by adding 30 g castor oil, orange oil, palm oil, shortening, or margarine vegetable oil based on 100 g of textured vegetable protein. They were then stored at -18 or -60 °C for 6 months and analyzed at one-month intervals. The meat analog supplemented with orange oil had the highest water content (64.85%; 66.07%), hardness (35.48 N; 34.05 N), and DPPH-radical-scavenging activity (30.01%; 30.87%) under -18 and -60 °C, respectively, as well as the highest liquid-holding capacity in different conditions. During frozen storage, temperature barely affected the meat quality. The storage stability of all meat analog samples was maintained for 6 months, although the quality was slightly reduced with an increase in storage duration. Coliform group bacteria were not detected regardless of the storage condition. In conclusion, all results supposed that orange oil can be a promising candidate for improving the juiciness and tenderness of meat analogs, and the quality of samples was maintained for at least 6 months under frozen storage. The findings of this study are relevant to the development and promotion of meat analog as an alternative to animal meat.

Microwave-Induced Rapid Shape Change of 4D Printed Vegetable-Based Food

Microwave heating acts as an environmental stimulus factor to induce rapid shape changes in 4D-printed stereoscopic models over time. The influence of microwave power and model structure on the shape change behavior was explored, and the applicability of the deformed method to other vegetable-based gels was verified. The results described that the G', G″, η, and proportion of bound water of yam gels increased with the increase in yam powder content, and the yam gel with 40% content had the best printing effect. The IR thermal maps showed the microwaves first gathered in the designed gully region caused the swelling phenomenon, which induced the printed sample to undergo a bird-inspired "spreading of wings" process within 30 s. Increasing the microwave power and microwave heating time were able to increase the bending angles and dehydration rates of the printed samples, thus improving the deformed degree and deformed speed. Different model base thicknesses (4, 6, 8, and 10 mm) also had significant effects on the shape change of the printed structures. The efficiency of the shape changes of 4D-printed structures under microwave induction can be judged by studying the dielectric properties of the materials. In addition, the deformed behaviors of other vegetable gels (pumpkin and spinach) verified the applicability of the 4D deformed method. This study aimed to create 4D-printed food with personalized and rapid shape change behavior, providing a basis for the application scenarios of 4D-printed food.

Three Phenolic Extracts Regulate the Physicochemical Properties and Microbial Community of Refrigerated Channel Catfish Fillets during Storage

It has been demonstrated that polyphenols have the potential to extend the shelf life of fish products. Thus, the effects of phenolic extracts from grape seed (GSE), lotus seedpod (LSPC), and lotus root (LRPE) were investigated in this study, focusing on the physicochemical changes and bacterial community of refrigerated channel catfish fillets during storage at 4 °C, using ascorbic acid (AA) as reference. As a result, GSE, LSPC, LRPE and AA inhibit the reproduction of microbials in catfish fillets during storage. According to the microbial community analysis, the addition of polyphenols significantly reduced the relative abundance of Proteobacterial in the early stage and changed the distribution of the microbial community in the later stage of storage. After 11 days of storage, the increase in total volatile base nitrogen (TVB-N) in fish was significantly reduced by 25.85%, 25.70%, 22.41%, and 39.31% in the GSE, LSPC, LRPE, and AA groups, respectively, compared to the control group (CK). Moreover, the lipid oxidation of samples was suppressed, in which thiobarbituric acid-reactive substances (TBARS) decreased by 28.77% in the GSE group, compared with the CK. The centrifugal loss, LF-NMR, and MRI results proved that GSE significantly delayed the loss of water and the increase in immobilized water flowability in catfish fillets. The polyphenol-treated samples also showed less decrease in shear force and muscle fiber damage in histology, compared to the CK. Therefore, the dietary polyphenols including GSE, LSPC, and LRPE could be developed as natural antioxidants to protect the quality and to extend the shelf life of freshwater fish.

Physicochemical Characteristics of Meat Analogs Supplemented with Vegetable Oils

This study identified the effect of the type and concentration of vegetable oil on the quality of meat analogs and analyzed the differences in their physiochemical characteristics. Various vegetable oils, such as castor oil, orange oil, palm oil, shortening, and margarine, were added to meat analogs. The meat analog was prepared by adding 10, 20, 30, 40, and 50 g of each vegetable oil based on 100 g of textured vegetable protein. The cooking loss, water content, liquid-holding capacity, texture, and antioxidant content of the meat analogs were assessed, and a sensory evaluation was performed. The meat analog with orange oil had a higher water content than the others, regardless of the amount of added oil, and it had a relatively high liquid-holding capacity. The DPPH(2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity of the meat analog with orange oil was higher than that of the others. The sensory evaluation also showed a decrease in soy odor and an increase in juiciness. Therefore, adding orange oil improves the preference, juiciness, soy odor, and quality of meat analogs. Our results demonstrate that orange oil has positive effects on the productivity of meat analogs and can help to improve meat analog consumption.

Recent application of artificial neural network in microwave drying of foods: a mini-review

The microwave-assisted thermal process is a high-efficiency drying method and is promising to be applied in the food industry. However, the prediction of the thermal treatment results from such a dynamic and complicated process can be difficult. Additionally, the determination of the optimal drying parameters, such as drying temperature, microwave power, and drying time for optimized performance can also be hard. Recently, extensive research has been focusing on the use of artificial neural network (ANN) models in the laboratory-scale microwave drying processes and has shown the feasibility of such application. As a regression tool, the ANN models have been widely used in predicting drying performance; when integrated with additional optimizing algorithms, the ANN models could be used for drying parameter optimization; and when combined with real-time measuring techniques (e.g. nuclear magnetic resonance), the ANN models could be used for monitoring and controlling the drying process in a dynamic sense. Future research could focus on testing the developed ANN models in industrial-scale microwave drying processes and applying the ANN models in microwave drying kinetics research for optimizing the dynamic drying processes. © 2022 Society of Chemical Industry.

Application progress of intelligent flavor sensing system in the production process of fermented foods based on the flavor properties

Fermented foods are sensitive to the production conditions because of microbial and enzymatic activities, which requires intelligent flavor sensing system (IFSS) to monitor and optimize the production process based on the flavor properties. As the simulation system of human olfaction and gustation, IFSS has been widely used in the field of food with the characteristics of nondestructive, pollution-free, and real-time detection. This paper reviews the application of IFSS in the control of fermentation, ripening, and shelf life, and the potential in the identification of quality differences and flavor-producing microbes in fermented foods. The survey found that electronic nose (tongue) is suitable to monitor fermentation process and identify food authenticity in real time based on the changes of flavor profile. Gas chromatography-ion mobility spectrometry and nuclear magnetic resonance technology can be used to analyze the flavor metabolism of fermented foods at various production stages and explore the correlation between flavor substances and microorganisms.

LF-NMR as a tool for predicting the 3D printability of surimi-starch systems

In this study, surimi from golden pompanos was mixed with starch to form a surimi-starch system. The water properties, rheological properties, and three-dimensional (3D) printability of the surimi-starch were measured. Cluster analysis results showed that the 3D printability was closely related to the type and addition content of starch, and the water and rheological properties. The low-field nuclear magnetic resonance (LF-NMR) parameters were used to predict 3D printability using polynomial regression models. The correlation coefficients (R²) for 3D printing accuracy and stability were 0.88 and 0.93, and the root mean square error (RMSE) values were 0.20% and 4.59%, respectively. In the verification test, the R² for the two models were 0.85 and 0.89, and the RMSE values were 0.20% and 1.06%, respectively. The nonlinear surface regression fitting exhibited superior predictive performance. Therefore, LF-NMR is a good non-destructive tool for quickly and accurately predicting the 3D printability of the surimi-starch systems.

Objective Measurements Associated with the Preferred Eating Qualities of Fermented Salamis

The development of new food products can be expedited by understanding the physicochemical attributes that are most relevant to consumers. Although many objective analyses are possible, not all are a suitable proxy to serve as quality markers associated with sensory preferences. In this work, we selected nine candidate laboratory assays to use on six commercial salamis, which were also eaten and informally described by a consumer discussion group familiar with China-sourced meat products. Several objective measures were strongly related to the flavour perceptions: (i) texture: instrumental texture values, fat release at oral temperature and fat saturation ratios, (ii) aroma: volatile compounds (e.g., alcohols and esters) associated with microbial fermentation and spices (terpenes and sulphur compounds) and (iii) taste: kokumi taste receptor responses. The fat released at oral temperature was associated with unsaturated fatty acids (r = 0.73). However, there was less explanatory worth for associations between sensory perceptions and proximate composition, water activity, pH or L*, a*, b* colourimetry.

Changes in moisture, colour, residual nitrites and N-nitrosamine accumulation of bacon induced by nitrite levels and dry-frying temperatures

The effects of different nitrite levels (50, 100, and 150 mg/kg meat) and dry-frying temperatures (100, 150, 200 and 250 °C) on the moisture movement, colour, sensory variables and residual nitrite and N-nitrosamine levels in smoked bacon were investigated. Increasing the dry-frying temperatures significantly increased the cooking loss and decreased the moisture content (P < 0.05). The bacon L*-values showed an increasing trend at first and then decreased, with the highest value of the bacon with 150 mg/kg nitrite was obtained at 100 °C and 150 °C. In addition, a*-values were significantly affected by the nitrite level and dry-frying temperature (P < 0.05), with the highest value of the bacon samples with 100 and 150 mg/kg nitrite observed at 250 °C. The residual nitrite content level initially increased (from unheated control to 150 °C) and then decreased (from 150 to 250 °C) sharply with increasing dry-frying temperatures in the bacon samples with the same sodium nitrite levels. N-methyl-N-nitrosoaniline (NMPhA) and N-nitrosomorpholine (NMOR) were measured in a number of smoked bacon samples, and a significant positive correlation (R² = 0.772) was found for N-nitrosamines (NA) contents and nitrite levels (P < 0.05). The maximum levels of NMPhA and NMOR were detected when the bacon with 150 mg/kg sodium nitrite was pan-fried at 200 °C and 150 °C, respectively.

Time-domain NMR analysis for the determination of water content in pharmaceutical ingredients and wet granules

The application of time-domain NMR (TD-NMR) analysis to quantify water content in pharmaceutical ingredients is demonstrated. The initial phase of the study employed a range of disintegrants with defined amounts of added water (0-30% of the total weight) as samples; the disintegrants included croscarmellose sodium, corn starch, low-substituted hydroxypropyl cellulose, and crospovidone. After acquisition of the T₂ relaxation curves of the samples by TD-NMR measurements, these curves were analyzed by partial least squares (PLS) regression. According to the analysis, accurate and reliable PLS models were created that enabled accurate assessment of water content in the samples. A powder blend consisting of acetaminophen (paracetamol) and tablet excipients was also examined. Both a physical mixture of the powder blend and a wet granule prepared with a high-speed granulator were tested as samples in this study. Precise determination of water content in the powder blend was achieved by using the TD-NMR method. The accuracy of water content determination was equivalent to or better than that of the conventional loss on drying method. TD-NMR analysis samples were measured nondestructively and rapidly with low cost; thus, it could be a powerful quantitative method for determining water content in pharmaceuticals.

Functional Characteristics of Lactobacillus and Yeast Single Starter Cultures in the Ripening Process of Dry Fermented Sausage

Dry fermented sausage is popular among the world because of its rich nutrition and unique flavor. Starter cultures play an important role in the quality of dry fermented sausage. In this study, probiotics lactic acid bacteria Lactobacillus delbrueckii N102, Latilactobacillus sakei H1-5, Debaryomyces hansenii Y4-1, and Wickerhamomyces anomalus Y12-3 were isolated from food-borne materials. The physicochemical properties, microbial populations, TBARS, lipolysis, proteolysis, and volatile flavor compounds of dry fermented sausages with different starter cultures were evaluated comparatively during the ripening process. The results showed that both L. delbrueckii N102 and L. sakei H1-5 grow well and could rapidly reduce the pH value of the products. At the same time, they could significantly reduce the number of Enterobacter putrefaciens, so as to ensure the safety of the products. In addition, the strains N102 promoted the formation of flavor compounds 2,3-butanedione, 3-hydroxy-2-butanone, and carnosine, whereas taurine content of batch H1-5 was significantly increased, while yeast y4-1 and y12-3 could also grow faster in sausage and promoted the esters and alcohols formation such as ethyl acetate and linalool, with the formation of γ-aminobutyric acid by y4-1. Compared with lactic acid bacteria, yeasts showed to contribute more in flavor formation and effective inhibition of lipid oxidation. The starter cultures played different roles in flavor contribution and had obvious differentiation in the ripening process of dry fermented sausage.

Evaluation of a Nondestructive NMR and MRI Method for Monitoring the Drying Process of Gastrodia elata Blume

Gastrodia elata Blume (G. elata) is a prominent traditional herb and its dry tuber is officially listed in the Chinese Pharmacopoeia. To ensure the quality of dried G. elata, the establishment of a nondestructive and convenient method to monitor the drying process is necessary. In this study, a nondestructive low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) method was introduced to monitor the drying process of G. elata. Three water states (bound, immobilized, and free) in G. elata samples were investigated through multiexponential fitting and inversion of the NMR data. The variation and distribution of the three water states during drying were monitored by LF-NMR, and the spatial distribution of water and internal structural changes were analyzed by MRI. Linear analysis of the moisture content, L* (lightness), b* (yellowness), and NMR parameters showed good correlations among them. Furthermore, partial least squares regression (PLSR) model analysis, which takes into account all NMR parameters, also showed good correlations among these parameters. All results showed that LF-NMR was feasible and convenient for monitoring moisture content. Therefore, LF-NMR and MRI could be used to monitor the moisture content nondestructively in the drying process of Chinese traditional herbs.