Effect of the Addition of Whole and Milled Flaxseed on the Quality Characteristics of Yogurt

Effects of Polygonatum sibiricum on Physicochemical Properties, Biological Compounds, and Functionality of Fermented Soymilk

The purpose of this study was to investigate the effects of Polygonatum sibiricum (P. sibiricum) on microbial fermentation, physicochemical properties, and functional properties of fermented soymilk. Three types of fermented soymilk were prepared. The first type was fermented directly from regular soymilk (fermented soymilk, FSM), and the other two were fermented after adding P. sibiricum (P. sibiricum fermented soymilk, P-FSM) or P. sibiricum polysaccharides (P. sibiricum polysaccharides fermented soymilk, PP-FSM). The differences in physical and chemical indexes such as pH value, acidity, and water-holding capacity were mainly compared, and the differences in the contents of functional components such as total phenols, total flavonoids, soy isoflavones, γ-aminobutyric acid, and organic acids were compared. The functionalities of the three samples in terms of antioxidant activity were evaluated, and the relevance of each active substance was explored. Compared with the FSM group, the addition of P. sibiricum and P. sibiricum polysaccharides could not only significantly promote the fermentation of Lactobacillus but also significantly improve the stability of the finished products during storage and prolong the shelf life of the finished product. The conversion rates of glycoside soybean isoflavones in the PP-FSM and P-FSM groups were 73% and 69%, respectively, which were significantly higher than those in the FSM group (64%). At the end of fermentation, the γ-aminobutyric acid contents of the PP-FSM and P-FSM groups were 383.66 ± 1.41 mg/L and 386.27 ± 3.43 mg/L, respectively, while that of the FSM group was only 288.66 ± 3.94 mg/L. There were also great differences in the content and types of organic acids among the three samples, especially lactic acid and acetic acid. By comparing the antioxidant capacity of DPPH (1,1-Diphenyl-2-picrylhydrazyl free radical), AB-TS (2,2'-Azinobis-3-ethylbenzthiazoline-6-sulphonate), and iron chelation, it was found that both PP-FSM and P-FSM were superior to FSM, and the antioxidant capacity had a certain correlation with the contents of total phenols and total flavonoids.

A study of flavor variations during the flaxseed roasting procedure by developed real-time SPME GC-MS coupled with chemometrics

Volatile compound variations during the roasting procedure play an essential role in the flaxseed-related product. In this work, we proposed a new strategy to high-throughput characterize the dynamic variations of flavors in flaxseed. Volatile compounds released at various roasting times were comprehensively investigated by a newly developed real-time solid-phase microextraction coupled with gas chromatography-mass spectrometry (GC-MS). Raw data files were analyzed by our advanced GC-MS data analysis software AntDAS-GCMS. Chemometric methods such as principal component analysis and partial least squares-discrimination analysis have realized the differences of samples with various roasting times. Finally, a total of 51 compounds from 11 aromas were accurately identified and confirmed with standards, and their variations as a function of roasting time were studied. In conclusion, we provided a new solution for the online monitoring of volatile compounds during the industrial roasting process.

Experimental Investigation and Modeling for the Influence of Adding Date Press Cake on Drinkable Yogurt Quality

The extraction of date syrup produces a large quantity of by-product known as date press cake (DPC). This study aimed to utilize valuable ingredients of the DPC by adding 0 (Control), 2, 4, and 6% (g/100 g) of its powder to drinkable yogurt before fermentation. The physicochemical properties, texture profile, and sensory evaluation of the treated DPC-based drinkable yogurt (DPC drinkable yogurt) were measured after fermentation and 5, 10, and 15 days of storage at 4 °C. The modeling of the most critical quality attributes, i.e., pH, acidity, syneresis, water holding capacity (WHC), viscosity, and color difference (ΔE), was conducted to predict their values based on the DPC percentage and storage period. The DPC drinkable yogurt’s total solids, protein, and fat ranged between 11.19–11.83, 3.10–3.42, and 2.26–2.34%, respectively. Adding 2–6% DPC slightly increased the pH of DPC drinkable yogurt and decreased its acidity (p > 0.05) during storage. Increasing the DPC percent in DPC drinkable yogurt decreased the syneresis value, and WHC increased during storage. The color parameters and viscosity of DPC drinkable yogurt recorded the highest value at the end of the storage period for all treatments and increased steadily with the increase in DPC. The evaluation of the prediction models indicated that the predicted values were close to the actual experimental values for pH (R2 = 0.779), acidity (R2 = 0.973), syneresis (R2 = 0.961), WHC (R2 = 0.989), viscosity (R2 = 0.99), L* (R2 = 0.919), a* (R2 = 0.995), b* (R2 = 0.922), and ΔE (R2 = 0.921). The textural analysis indicated that increasing the concentration of DPC in the DPC drinkable yogurt increased hardness (g), springiness, cohesiveness, and gumminess and decreased adhesiveness and resilience during cold storage. The evaluation of sensory acceptance during the cold storage of the DPC drinkable yogurt was conducted by 30 expert panelists. Each panelist received four cups of 10 mL drinkable yogurt treatments at 5–10 °C. The evaluation results indicated that adding 2% of DPC was closest in overall sensory acceptability to the control sample (p < 0.05). This study revealed the potential use of DPC in drinkable yogurt as a natural, functional, and low-cost ingredient to improve the fiber content, physicochemical properties, and overall acceptability. Therefore, the fermented DPC-based yogurt drink has the potency to be a practical, value-added, and novel alternative to dairy-based yogurt.

Composition, processing, and quality control of whole flaxseed products used to fortify foods

Whole flaxseed (flour) as a good source of omega-3 fatty acid and phytochemicals with excellent nutritional and functional attributes has been used to enrich foods for health promotion and disease prevention. However, several limitations and contemporary challenges still impact the development of whole flaxseed (flour)-enriched products on the global market, such as naturally occurring antinutritional factors and entrapment of nutrients within food matrix. Whole flaxseed (flour) with different existing forms could variably alter the techno-functional performance of food matrix, and ultimately affect the edible qualities of fortified food products. The potential interaction mechanism between the subject and object components in fortified products has not been elucidated yet. Hence, in this paper, the physical structure and component changes of flaxseed (flour) by pretreatments coupled with their potential influences on the edible qualities of multiple fortified food products were summarized and analyzed. In addition, several typical food products, including baked, noodle, and dairy products were preferentially selected to investigate the potential influencing mechanisms of flaxseed (flour) on different substrate components. In particular, the altered balance between water absorption of flaxseed protein/gum polysaccharides and the interruption of gluten network, lipid lubrication, lipid-amylose complexes, syneresis, and so forth, were thoroughly elucidated. The overall impact of incorporating whole flaxseed (flour) on the quality and nutritional attributes of fortified food products, coupled with the possible solutions against negative influences are aimed. This paper could provide useful information for expanding the application of whole flaxseed (flour) based on the optimal edible and nutritional properties of fortified food products.

Could Dietary Supplementation with Different Sources of N-3 Polyunsaturated Fatty Acids Modify the Rabbit Gut Microbiota?

The present study evaluated the effects of feed supplemented with two dietary sources of n-3 polyunsaturated fatty acids (PUFAs; fish oil and extruded flaxseed) on the gut microbiota, caecal fermentations, gastrointestinal histology, and histochemistry in rabbits. Fifteen male New Zealand White rabbits were divided into three groups (n = 5/group) and fed with different diets from weaning (35 days of age) until slaughtering (90 days of age): C group, fed with a commercial diet; F group, supplemented with 10% of extruded flaxseed; and O group, supplemented with 3.5% of fish oil. At slaughter, the content of the stomach, duodenum, jejunum, ileum, caecum, and colon was collected and analyzed by Next Generation 16S rRNA gene sequencing. Tissue samples of the same tracts were evaluated with histological and histochemical analysis. Ammonia and lactic acid in the caecum were also quantified. Twenty-nine operational taxonomic units (OTUs) were significantly different between groups. Groups receiving n-3 PUFAs supplementation showed an increase in Bacteroidetes and Lachnospiraceae in several gastrointestinal tracts, while Bacilli abundance, as well as Firmicutes/Bacteroidetes ratio, were reduced compared to the control group (for all p < 0.05). Caecal ammonia was lower in the F than C group (p < 0.032), whereas no difference was found for lactic acid. Finally, histological evaluations revealed a mild hemorrhagic infiltration and vessels ectasia in the stomach mucosa of both F and O groups, but no effect of nutritional treatment was evidenced by the histochemical analyses. In conclusion, n-3 PUFAs supplementation could modify the rabbit gut microbiota and fermentation. The increase in beneficial bacterial populations may, at least partially, explain the positive effects of n-3 PUFAs diet supplementation on human and animals’ health, although the appropriate dosage should be established.

Legumes and Legume-Based Beverages Fermented with Lactic Acid Bacteria as a Potential Carrier of Probiotics and Prebiotics

Fermentation is widely used in the processing of dairy, meat, and plant products. Due to the growing popularity of plant diets and the health benefits of consuming fermented products, there has been growing interest in the fermentation of plant products and the selection of microorganisms suitable for this process. The review provides a brief overview of lactic acid bacteria (LAB) and their use in fermentation of legumes and legume-based beverages. Its scope also extends to prebiotic ingredients present in legumes and legume-based beverages that can support the growth of LAB. Legumes are a suitable matrix for the production of plant-based beverages, which are the most popular products among dairy alternatives. Legumes and legume-based beverages have been successfully fermented with LAB. Legumes are a natural source of ingredients with prebiotic properties, including oligosaccharides, resistant starch, polyphenols, and isoflavones. These compounds provide a broad range of important physiological benefits, including anti-inflammatory and immune regulation, as well as anti-cancer properties and metabolic regulation. The properties of legumes make it possible to use them to create synbiotic food, which is a source of probiotics and prebiotics.

Effect of Supercritical Extract from Black Poplar and Basket Willow on the Quality of Natural and Probiotic Drinkable Yogurt

Yogurt is a fermented milk drink produced by Streptococcus thermophilus, Lactobacillus delbrüeckii ssp. bulgaricus, or Lactobacillus rhamnosus, which can be enriched with polyphenolic compounds to enhance its antioxidant properties. Supercritical (scCO2/H2O) extracts obtained from the mixture of bark and wood of black poplar (Populus nigra) and basket willow (Salix viminalis) are the source of bioactive compounds. The aim of the study was to assess the effect of supercritical extracts from the P. nigra and S. viminalis on the fermentation, quality, and bioactive properties of drinkable natural and probiotic yogurts. The incorporation of scCO2/H2O extracts at a dose of 0.01% (w/v) into milk for the production of natural and probiotic yogurts increases their functional properties by enhancing the antioxidant activity without causing negative effects on the physicochemical and organoleptic properties of products. The antioxidant activity of yogurt with scCO2/H2O extract from P. nigra and S. viminalis was higher than control yogurts by 1.3-13.2% and 4.4-37.5%, respectively. The addition of a supercritical S. viminalis extract reduced the time of natural and probiotic yogurt fermentation. Natural and probiotic yogurt with scCO2/H2O extracts added was characterised by a bacterial population size of over 7 log cfu/g, and the microflora was active throughout the cold storage period. FTIR analysis confirmed the presence of scCO2/H2O extracts from P. nigra or S. viminalis in both types of yogurt. A secondary structure analysis confirmed interactions between compounds of scCO2/H2O extract from P. nigra and S. viminalis extract with milk proteins. These interactions affect the compounds' structural and functional properties by changing, e.g., their digestibility and antioxidant properties.