A high-throughput differential scanning fluorimetry method for rapid detection of thermal stability and iron saturation in lactoferrin.

Thermal stability and iron saturation of lactoferrin (LF) are of great significance not only for the evaluation of the biological activities of LF but also for the optimization of the isolation and drying process parameters. Differential scanning calorimetry (DSC) is a well-established and efficient method for thermal stability and iron saturation detection in LF. However, multiple DSC measurements are typically performed sequentially, thus time-consuming and low throughput. Herein, we introduced the differential scanning fluorimetry (DSF) approach to overcome such limitations. The DSF can monitor LF thermal unfolding with a commonly available real-time PCR instrument and a fluorescent dye (SYPRO orange or Glomelt), and the measured melting temperature of LF is consistent with that determined by DSC. On the basis of that, a new quantification method was established for determination of iron saturation levels using the linear correlation of the degree of ion saturation of LF with DSF measurements. Such DSF method is simple, inexpensive, rapid (<15 min), and high throughput (>96 samples per experiment), and provides a valuable alternative tool for thermal stability detection of LF and other whey proteins.

Characterization of fermented pomegranate juice: ACE inhibitory activity under in vitro digestion, antioxidant capacity, phenolics composition, chemical properties and sensory evaluation.

Consuming pomegranate juice (PJ) is beneficial for hypertensive regulation because of the phenolic compounds in PJ and their inhibitory activity on angiotensin-I-converting enzyme (ACE). To better utilize bioactive function of food, microorganism fermentation has been adopted to alter phenolic metabolism. This study confirms that even under in vitro digestion, fermented PJ (FPJ) maintains higher ACE inhibitory activity than that of PJ. The main phenolic compounds in PJ were compared either under fermentation or in vitro digestion. This study finds that fermentation promotes antioxidant capacity of PJ. The chemical properties of FPJ are evaluated and the corresponding relationship with bioactivities is analyzed. A sensory evaluation comparison is conducted between FPJ and PJ, furnishing interesting information for consumers. This study highlights the relationship between ACE inhibitory activity of PJ and phenolic composition under fermentation and in vitro digestion, providing novel insights for diet regulation of phenolic-rich FPJ in ACE inhibition therapy. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01388-w.

Dynamic Crushing Behavior of Ethylene Vinyl Acetate Copolymer Foam Based on Energy Method.

This paper aimed to experimentally clarify the dynamic crushing mechanism and performance of ethylene vinyl acetate copolymer (EVA) and analyze the influence of density and thickness on its mechanical behavior and energy absorption properties under dynamic impact loadings. Hence, a series of dynamic compression tests were carried out on EVA foams with different densities and thicknesses. When the impact energy is 66.64 J, for foam with a density of 150 kg/m3, the maximum contact force, maximum displacement, maximum strain, absorbed energy, and specific energy absorption (SEA) increased by 20 ± 2%, -38.5 ± 2%, -38.5 ± 2%, 4 ± 2%, and 105 ± 2%, respectively, compared to foam with a density of 70 kg/m3. The ratios of absorbed energy to impact energy for different thickness specimens are almost equal. The specimen density has no effect on the efficiency of energy absorption and has a greater effect on the SEA. Meanwhile, when the impact energy-to-thickness ratio is 1680 J/m, compared to foam with a thickness of 30 mm, the maximum contact force, maximum displacement, maximum strain, absorbed energy, and SEA for foam with a thickness of 60 mm increased by 28.5 ± 2%, 211.3 ± 2%, 56.6 ± 2%, 100.8 ± 2%, and 0.4 ± 0.5%, respectively. When the impact energy is 66.64 J, compared to foam with a thickness of 30 mm, the maximum contact force, maximum displacement, maximum stain, absorbed energy, and SEA for foam with a thickness of 60 mm increased by -42.5 ± 2%, 163.5 ± 2%, 31.7 ± 2%, 4.1 ± 2%, and 4.1 ± 2%, respectively. The SEA of two different-thickness EVA specimens is almost equal, about 2.8 J/g. The ratios of absorbed energy to impact energy for different thickness specimens are almost equal, both at 72%. The specimen thickness has no effect on the efficiency of energy absorption and has a greater effect on the maximum contact force. In the range of impact energy, thickness, and density studied, the absorbed energy and SEA are not affected by the thickness of EVA specimens and are determined by the impact energy. The density has no significant effect on the absorbed energy but has a greater effect on the SEA. However, for EVA foams, the greater the density, the greater the mass, and the higher the cost. Taking into account lightweight and cost factors, when optimizing cushioning design within a safe range, we can choose EVA foams with a smaller density and thickness.

Crushing Responses of Expanded Polypropylene Foam.

This paper aimed to experimentally clarify the crushing mechanism and performance of expanded polypropylene foam (EPP) and analyze the influence of density and thickness on its mechanical behavior and energy absorption properties under static crushing loadings. Hence, a series of compression tests were carried out on EPP foams with different densities and thicknesses. For foam with a density of 60 kg/m3, the mean crushing strength, energy absorption (Ea), energy absorption efficiency (Ef), specific energy absorption (SEA), and energy absorption per unit volume (w) increased by 245.3%, 187.2%, 42.3%, 54.3%, and 242.8%, respectively, compared to foam with a density of 20 kg/m3. Meanwhile, compared to foam with a thickness of 30 mm, the mean crushing strength, energy absorption (Ea), energy absorption efficiency (Ef), SEA, and energy absorption per unit volume (w) for foam with a thickness of 75 mm increased by 53.3%, 25.2%, -10.8%, -4.7%, and -10.6%, respectively. The results show that foam density has a significantly greater influence on static compressive performance than foam thickness. The microstructures of the EPP foam before and after static compression were compared by observing with a scanning electron microscope (SEM), and the failure mechanism was analyzed. Results showed that the load and energy as well as the deformation and instability processes of its cells were transferred layer by layer. The influence of density on the degree of destruction of the internal cells was obvious. Due to its larger mass and larger internal damping, thicker foams were less damaged, and less deformation was produced. Additionally, the EPP foam exhibited a considerable ability to recover after compression.

Health potential of fermented goat dairy products: composition comparison with fermented cow milk, probiotics selection, health benefits and mechanisms.

Goat milk as a preferable probiotic vehicle has been investigated and the contribution of fermented goat dairy products to the nutritional and economic wellbeing of the world is tremendous. This review presents the recent progress on fermented goat dairy products, including probiotic selection, composition comparison to fermented cow milk, health effects, and related mechanisms. Fermented goat milk maintains a better nutritional profile in comparison to fermented cow milk with higher values of protein, minerals (Ca, Mg, Fe, Cu, Zn and Se), vitamins (A, D3 and B12) and some fatty acids. Lactobacillus is the predominant genus used in goat milk fermentation and endows goat milk with higher functional value, including gut microbiota regulation, anti-microbial and anti-inflammatory functions, hypocholesterolemic effects, antioxidant effects, hypotensive effects, bone health, anemia recovery, anti-obesity, and anti-atherogenic function. The corresponding mechanisms have been elucidated at the molecular level. A series of collection on probiotics starters, fermentation strategy and characteristics of fermented goat dairy products are performed. Although the industrial applications of fermented goat milk remain underdeveloped, the improved functional annotation and fermentation strategy identified in this review provide a bright future and an excellent framework for the future fermented goat dairy market.

Enhanced antihypertensive potential of fermented pomegranate juice: The contribution of phenolic compounds biotransformation and the resultant angiotensin-I-converting enzyme inhibition mechanism.

Current research on plant food-derived phenolic compounds as angiotensin-I-converting enzyme (ACE) inhibitors has been well documented. Pomegranate juice (PJ) has been reported positively contributed to ACE inhibition. Microbial fermentation is a preferable technique to regulate the biotransformation of phenolic compounds and their bioaccessibility, therefore promoting the ACE inhibitory activity in plant food with antihypertension potential. In this study, the remarkable improvements of ACE inhibitory activity and antioxidant capacity in Lactobacillus plantarum fermented PJ were observed. A consecutive study of phenolic compounds biotransformation, ACE inhibition kinetics and structure-activity relationship were performed. This study firstly highlights the relationship between the enhanced ACE inhibitory activity in fermented PJ and the biotransformation of phenolic compounds, providing a new way to reinforce plant food ACE inhibition potential by microbial fermentation.

UHPLC-Q-Exactive Orbitrap MS/MS-Based Untargeted Metabolomics and Molecular Networking Reveal the Differential Chemical Constituents of the Bulbs and Flowers of Fritillaria thunbergii.

Both the bulbs and flowers of Fritillaria thunbergii Miq. (BFT and FFT) are widely applied as expectorants and antitussives in traditional Chinese medicine, but few studies have been conducted to compare the chemical compositions of these plant parts. In this study, 50% methanol extracts of BFT and FFT were analyzed via UHPLC-Q-Exactive Orbitrap MS/MS, and the feasibility of using non-targeted UHPLC-HRMS metabolomics and molecular networking to address the authentication of bulb and flower samples was evaluated. Principal component analysis (PCA), Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA), and heat map analysis showed there were dissimilar metabolites in BFT and FFT. As a result, 252 and 107 peaks in positive ion mode and negative mode, respectively, were considered to represent significant difference variables between BFT and FFT. Then, MS/MS-based molecular networking of BFT and FFT was constructed to perform an in-depth characterization of the peaks using different variables. A total of 31 alkaloids with significant differences were annotated in this paper, including seven cis-D/E-vevanine without C20-OH and one trans-D/E-cevanine with C20-OH, thirteen trans-D/E-cevanine without C20-OH, five cevanine N-oxide, and five veratramine. Among the 31 alkaloids, eight alkaloids had higher FFT than BFT contents, while all the flavonoids identified in our work had greater FFT than BFT contents. The influence of different ingredients on the pharmacological activities of BFT and FFT should be investigated in future studies.

Preparation of Saccharomyces boulardii powder by spray drying: thermoprotectants optimization and stability evaluation.

Saccharomyces boulardii as the probiotic yeast was widely used in the pharmaceutical, feed and food industries. The influence of skim milk, gelatin, and carbohydrates on the heat resistance of S. boulardii is explored in the article. Response surface methodology was effectively applied to optimize the thermoprotectant composition for S. boulardii during spray-drying. The accelerated test is applied to evaluate its the subsequent storage stability. The results show that the thermoprotectants composition was comprehensively optimized such as: 15.12% skim milk, 1.81% gelatin, and 9.73% trehalose. The highest viability was 17.77%, which was basically the same as the predicted value of 18.21%. The inactivation rate constant of spray-dried powder was k-18 = 1.04 × 10-5 h-1, the quantity of viable cells stored at this temperature for 1 and 10 years was 8.25 × 108 CFU/g and 1.25 × 108 CFU/g, separately. This work provides a thermoprotectants formula for the S. boulardii during the spray drying process.

Antihypertensive potential of fermented milk: the contribution of lactic acid bacteria proteolysis system and the resultant angiotensin-converting enzyme inhibitory peptide.

Hypertension has become an increasing health concern given that it is a major risk for cardiovascular disease. Synthetic antihypertensive drugs, including angiotensin-converting enzyme (ACE) inhibitors, effectively control high blood pressure but are associated with unpleasant side effects. Milk fermented by certain lactic acid bacteria (LAB) provides energetic contributions to the management of hypertension, especially the regulation of ACE. LAB are important food-grade microbial organisms that release ACE inhibitory peptides through their unique proteolysis system, which consists of cell-envelope proteinases (CEPs), transporter systems, and intracellular peptidases. Thus, the description of LAB proteolysis system genes and their contributions to ACE inhibitory peptide production is a challenging but promising study. This review provides a survey of LABs with potential ACE inhibitory activity and investigates the research progress of LAB proteolytic systems with an emphasis on the correlation of their components and ACE inhibitory activity. Subsequently, a depiction of the ACE inhibitory peptide action mechanism, structure-activity relationship and bioavailability is presented. The improved functional annotation of LAB proteolytic system genes will provide an excellent framework for future experimental validations of predicted ACE inhibitory activity in fermented milk.

Antihypertensive Potential of Plant Foods: Research Progress and Prospect of Plant-Derived Angiotensin-Converting Enzyme Inhibition Compounds.

Global health concerns are clearly evidenced by cardiovascular disease, kidney damage, and heart attacks. Antihypertensive synthetic drugs, including angiotensin-converting enzyme (ACE) inhibitors, effectively control hypertension but with unpleasant side effects. In recent decades, studies on the role of food-derived compounds have provided a positive contribution to ACE regulation. Here, the research progress of plant food-derived phenolic compounds as ACE inhibitors is reviewed. A survey of bioactive compounds of plant food is presented to broaden the source scope of natural ACE inhibitors. A consecutive understanding of plant-derived ACE inhibitors classification, inhibition mechanism, structure-activity relationship, and bioavailability are scientifically organized. The emerging evidence highlights areas that need further research, including those related to molecular structure, bioaccessibility, and interactions with gut microflora. Future research on such topics may encourage basic research and clinic application to exploit these plant food constituents as novel ACE inhibitors.

Comprehensive Understanding of the Relationship between Bioactive Compounds of Black Tea and its Angiotensin Converting Enzyme (ACE) Inhibition and Antioxidant Activity.

Long term regular intake of black tea (BT) can lower blood pressure, which is probably due to its antioxidant activity and angiotensin converting enzymes (ACE) inhibitory activity. This study achieves a comprehensive understanding of the relationship between bioactive compounds of BT and its ACE inhibitory activity and antioxidant activity. Phenolic compounds are closely related to antioxidant activity and ACE inhibitory activity. Catechin (C) exhibits stronger inhibitory activity on ACE enzyme than that of other compounds. Molecular docking demonstrates that C could directly bind to ACE active site pockets and Zn(II). Other bioactive compounds are involved in antioxidant and ACE inhibitory activity in varying degrees but no obvious trend is established. Our study proposes a conjecture that some bioactive compounds of BT regulate antioxidant defenses through mechanisms that involve ACE. The mixed mode of in vitro inhibition of ACE and oxidant of BT bioactive compounds needs to be further investigated.

Screening of gamma-aminobutyric acid-producing lactic acid bacteria and its application in Monascus-fermented rice production.

BACKGROUND: Gamma-aminobutyric acid (GABA), with an antidepressant effect, and Monacolin K, with a cholesterol-lowering effect, are the main bioactive ingredients in Monascus-fermented rice (MFR). The simultaneous enrichment of both ingredients can effectively enhance the health benefits of MFR. However, the capacity of Monascus spp. to produce GABA is limited. METHODS: Seventeen lactic acid bacteria (LAB) strains were preliminarily screened for GABA-producing by whole-cells bioconversion of L-glutamate, followed by rescreening through fermentation with the addition of the precursor L-glutamic acid. Subsequently, the bioconversion conditions (temperature, metal ions, and pH) for the conversion of L-monosodium glutamate (MSG) were investigated. Additionally, the GABA-producing LAB was co-inoculated with a monacolin K producing strain Monascus anka 20-2, and the ratio of M. anka 20-2 to LAB in microbial consortia was optimized for MFR production. RESULTS: The strain Lactobacillus plantarum 8014 was screened out for its ability to produce GABA. At an optimal temperature of 33°C and pH 7.5, with the addition of 0.05 g/L ZnSO4, the strain showed an L-glutamate conversion rate of 100%. The ratio optimization of M. anka 20-2 to L. plantarum 8014 in microbial consortia showed that when the dry cell ratio was 2:1, the content of monacolin K and GABA in the MFR simultaneously reached 2.22 mg/g and 29.9 mg/g, respectively. CONCLUSIONS: A two-stage fermentation using microbial consortia containing M. anka 20-2 and L. plantarum 8014 was developed for the production of bioactive MFR, in which the active ingredients monacolin K and GABA were simultaneously enriched, with good consumer acceptability due to the aromatic scent produced by lactic acid bacteria.

Analysis of the complexation process between starch molecules and trilinolenin.

Starch is a basic biomacromolecule, and an in-depth understanding of the process and mechanism of starch-lipid complexation has great significance for starch based food and pharmaceutical. In this study, molecular dynamics simulation was used to explore the complexation details between starch molecules and trilinolenin, such as complexation process, interaction forces, conformation changes and stability changes, which are difficult to be verified by using other characterization methods. The results show that, firstly, starch residues of one turn helix (8 residues) are enough to bind a trilinolenin molecule firmly. Secondly, the complex is maintained by Van der Waals and electrostatic interaction. Thirdly, the residues complexed with trilinolenin become more stable than the former or the free residues. In brief, the complexation process, interaction forces, conformation changes and stability changes of the starch-trilinolenin complex were clarified in this study. The results may create new insights for the research about the interaction of starch and lipid, then provide theoretical guidance for the research on starch based food and pharmaceutical.

Nutrition and aroma challenges of green tea product as affected by emerging superfine grinding and traditional extraction.

Green tea, superfine green tea powder (SGTP), and tea extract were prepared to determine their chemical components and antioxidant activity. The nutrition and aroma challenges of green tea during traditional extract technique and superfine grinding were profiled in this study. The traditional extract technique took advantage over superfine grinding in L-theanine and glutamic acid (Glu) preservation, but not in other 16 essential amino acids. SGTP preserved a maximum of elements from green tea, whereas tea extract greatly changed the elements ratio. Tea extract contained higher VB2 and VC contents and doubled the tea polyphenol (TP) content in comparison with green tea and SGTP. Additionally, tea extract contained more favorable aroma compounds and maintained stronger antioxidant activity in comparison with green tea and SGTP. This study profiled an important basis for the comprehensive utilization of green tea resources by consumers and manufacturers.

Collaborative optimization and molecular docking exploration of novel ACE-inhibitory peptides from bovine milk by complex proteases hydrolysis.

Food-originated angiotensin-I-converting enzyme (ACE)-inhibitory peptides to preserve hypertension are widely investigated over the past decade. Our research aims to discovery novel ACE-inhibitory peptides from bovine milk by couple of complex proteases (alcalase and protease). By means of response surface methodology with the conditions of pH 9.01, 61.81 °C and 6.5% ratio of enzyme to substrate, the hydrolysis model contributes to best-performing ACE-inhibitory activity of 85.02%. Through the further purification by consequent ultrafiltration, macroporous resin and gel chromatography, fraction G2-2 is eventually obtained with ACE-inhibitory activity as high as 92.7%. Two novel peptides of VLPVPQ and VAPFPE are identified by Q-Exactive LC-MS/MS. The molecular docking study further suggests that two novel peptides have good combinations of the S1 and S2 active site pockets and Zn(II) of ACE. Our study provides a fitted mathematical model to produce two novel milk-derived ACE-inhibitory peptides, potentially developing the functional foods, especially for hypertension therapy as initial treatment.

Effect of prebiotics, inorganic salts and amino acids for cell envelope proteinase production from Lactobacillus plantarum LP69.

BACKGROUND: Cell-envelope proteinases (CEPs) can improve the texture and organoleptic characteristics of dairy products, and may also cause the release of bioactive peptides, which contribute to improving the host’s health. Thus, the CEPs with high activity produced by L. plantarum has great potential in the development of functional dairy products. METHODS: A single factor experiment was used to investigate the effects of prebiotics (inulin, stachyose, isomaltooligosaccharide, xylooligosaccharides, galactooligosaccharides and fructooligosaccharides), inorganic salts (Na2HPO4, NaH2PO4, K2HPO4, KH2PO4, CH3COONa and C6H14N2O7) and amino acids (arginine, leucine, serine, lysine, alanine and glutamic acid) on the activity of cell envelope proteinases (CEPs), specific activity, protein content, OD600 value and pH in MRS broth fermented by Lactobacillus plantarum LP69. RESULTS: The optimum concentration of inulin (0.7%), isomaltooligosaccharide (0.5%), Na2HPO4 (0.4%), CH3COONa (0.4%), leucine (20 mg/L), serine (20 mg/L) for L. plantarum LP69 was estimated with the activity of CEP in the range 17.36–21.47 U/mL, protein content in the range 19.18–22.53 mg/mL, specific activity in the range 0.77–1.12 U/mg. CONCLUSIONS: Inulin, isomaltooligosaccharide, Na2HPO4, CH3COONa, leucine and serine are superior to other selected substances, and have a significant influence on the CEP activity and specific activity of L. plantarum LP69. This would provide a reference for further optimization of CEP-producing media of L. plantarum LP69.

Optimization of composite cryoprotectant for freeze-drying Bifidobacterium bifidum BB01 by response surface methodology.

Freeze drying has been well applied in the preparation of high-efficiency probiotic powders. However, the process is generally accompanied by probiotic viability deficiency, which is the bottleneck for further application. To improve the viability of Bifidobacterium bifidum BB01 during freeze-drying, we optimized the cryoprotectant of B. bifidum BB01 by response surface methodology (RSM) with a Central Composite Design (CCD). In this study, two values of B. bifidum BB01 with different protectant factors were investigated, including freeze-drying survival rate and the viable counts of per unit weight of freeze-dried powder. The optimized cryoprotectants were obtained as follows: glycine of 5.5%, sodium bicarbonate of 0.8%, xylo-oligosaccharides of 7%, arginine of 4.5% and skim milk of 25%. The survival rate and the viable counts of per unit weight of powder were 90.37 ± 1.9% and (2.78 ± 0.13) × 1011cfu·g-1, respectively, both close to the predicted value (88.58% and 2.71 × 1011 cfu·g-1). Our research demonstrated that RSM was successful in optimizing composite cryoprotectant for freeze-dried powder of B. bifidum which can as well protect the probiotic cells.

Bispectral Index Values Are Accurate Diagnostic Indices Correlated With Glasgow Coma Scale Scores.

OBJECTIVE: The Glasgow Coma Scale (GCS) is widely used in neurosurgery to evaluate the depth of coma in patients with brain injury. The bispectral index (BIS) was developed primarily to monitor the depth of unconsciousness. Recent evidence suggests that BIS may also help in the assessment of brain injury. This study explores the correlation between GCS scores and BIS values in patients with brain injury. METHODS: Fifty patients were divided into 2 groups-moderate (GCS 9-12) and severe (GCS 3-8)-in this prospective, double-blind, observational study. Bispectral index data were recorded when electromyography was less than 40 and signal quality index was greater than 75 for 5 minutes. Linear regression was used to examine the correlation between BIS and GCS, and receiver operating characteristic curves were plotted. Cutoff points were identified to show the feasibility and accuracy of BIS for assessing brain injury. RESULTS: The mean BIS value of the moderate group was 65.62 ± 12.84, and that of the severe group was 46.27 ± 17.35. Bispectral index values were significantly correlated with GCS (R = 0.729, P < .01). The regression line and 95% confidence interval were determined; the regression equation was BIS = 5.46*GCS + 12.72. The receiver operating characteristic curve showed high diagnostic accuracy when GCS is less than 9; the area under the curve was 0.8164, and the cutoff point (BIS value) corresponding to the maximum sensitivity (0.91) and specificity (0.63) was 60.2. CONCLUSION: BIS values and GCS scores were significantly correlated in patients with brain injury. As a continuous and objective measurement, BIS is a viable evaluation and monitoring tool for brain injury.

Optimization of Nutrient Composition for Producing ACE Inhibitory Peptides from Goat Milk Fermented by Lactobacillus bulgaricus LB6.

Hypertension is a serious threat to human health and food-derived angiotensin converting enzyme (ACE; EC 3.4.15.1) inhibitory peptides can be used to regulate high blood pressure without side effects. The composition of the nutrient medium for the production of these peptides by fermenting goat milk with Lactobacillus bulgaricus LB6 was optimized to increase the ACE inhibitory activity by Box-Behnken design (BBD) of response surface methodology (RSM) in the present study. Soybean peptone, glucose, and casein had significant effects on both ACE inhibition rate and viable counts of L. bulgaricus LB6 during incubation. The results showed that the maximum values of ACE inhibition rate and viable counts for L. bulgaricus LB6 were reaching to 86.37 ± 0.53% and 8.06 × 107 under the optimal conditions, which were 0.35% (w/w) soybean peptone, 1.2% (w/w) glucose, and 0.15% (w/w) casein. The results were in close agreement with the model prediction. The optimal values of the medium component concentrations can be a good reference for obtaining ACE inhibitory peptides from goat milk.

Application of the Plackett-Burman design to determine the main factors affecting the anti-oxidative activity of goat's milk casein hydrolyzed by Alcalase and papain.

BACKGROUND: Antioxidant peptides can scavenge excessive free radicals produced by the metabolism, main- tain a free radical balance and prevent aging and disease. Therefore, finding natural resources with strong antioxidant activity has become a new focus for research. METHODS: Single-factor experiments were used to investigate the effects of various factors (hydrolysis temperature, pH, substrate concentration, enzyme to substrate ratio (E/S), ratio of compound protease (EAlcalase/Epapain) and time on the preparation of antioxidant peptides by compound protease (Alcalase and papain) hydrolysis of goat’s milk casein. Then, a Plackett-Burman design was used to determine the sig- nificant factors for the preparation of antioxidant peptides by hydrolysis of goat’s milk casein with compound protease. RESULTS: The results of the single-factor experiments indicated that the highest anti-oxidative activity of pep- tides would be obtained at a hydrolysis temperature of 55°C, a pH of 7.5, a substrate concentration of 3.0%, an E/S of 4.0%, a ratio of compound protease of 1/3 and a hydrolysis time of 180 min. CONCLUSIONS: The main factors affecting the activity of anti-oxidative peptides hydrolyzed from goat’s milk casein with compound protease were determined by Plackett-Burman design and the results showed that temperature, E/S ratio and the ratio of compound protease had significant influences on the production of antioxidant peptides. This could provide a basis and reference for further optimization.