The effect of enzyme systems and processing on the hydrolysis of peanut (Arachis hypogaea L.) protein

Peanut oils from roasting operations: An overview of production technologies, flavor compounds, formation mechanisms, and affecting factors

Fragrant peanut oils (FPOs) are commonly defined as edible peanut oils having strong natural roasted peanut flavor without peculiar unpleasant odors and produced from peanut kernels through roasting/steaming and pressing operations, etc. The flavor of FPOs plays a crucial role in their acceptability and applications and their flavor profiles are an important factor in determining their overall quality. This paper presents a systematic literature review of recent advances and knowledge on FPOs, especially their flavors, in which it is focused on the evaluation of volatile compounds, the factors influencing the formation of flavor compounds, and formation mechanisms of those typical flavor compounds. More than 300 volatiles are found in FPOs, while some key aroma-active compounds and their potential formation pathways are examined. Factors that have big influences on flavor are discussed also, including the properties of raw materials, processing technologies, and storage conditions. Ultimately, the paper highlights the challenges facing, including the challenges in flavor analysis, the relationship between volatile compounds and sensory attributes, as well as the opening of the blackboxes of flavor formations during the processing steps, etc.

Kinetics of Egg-Yolk Protein Hydrolysis and Properties of Hydrolysates

Lecithin-free egg yolk (LFEY) is a byproduct of the extraction of egg-yolk phospholipids, which contain approximately 46% egg yolk proteins (EYPs) and 48% lipids. The enzymatic proteolysis is the alternative to increase the commercial value of LFEY. The kinetics of proteolysis in full-fat and defatted LFEY with Alcalase 2.4 L was analyzed in terms of the Weibull and Michaelis-Menten models. A product inhibition effect was also studied in the full-fat and defatted substrate hydrolysis. The molecular weight profile of hydrolysates was analyzed by gel filtration chromatography. Results pointed out that the defatting process did not importantly affect the maximum degree of hydrolysis (DH_max) in the reaction but rather the time at which DH_max is attained. The maximum rate of hydrolysis (V_max) and the Michaelis-Menten constant K_M were higher in the hydrolysis of the defatted LFEY. The defatting process might have induced conformational changes in the EYP molecules, and this affected their interaction with the enzyme. Consequently, the enzymatic reaction mechanism of hydrolysis and the molecular weight profile of peptides were influenced by defatting. A product inhibition effect was observed when adding 1% hydrolysates containing peptides lower than 3 kDa at the beginning of the reaction with both substrates.

Preparation and identification of anti-breast cancer cells peptides released from yak milk casein

Yak milk casein (YMC) is the main protein in the yak milk. Peptides released from Yak milk casein (YMC) have multiple bioactivities, including anti-inflammation and immune-regulation, suggesting that these peptides might be able to inhibit cancer theoretically. However, the anti-cancer peptides from YMC have only been sparsely studied. Breast carcinoma is the most common carcinoma in women worldwide. Thus, the paper herein was to identify yak milk casein (YMC)-derived anti-breast cancer peptides via gel filtration, reversed phase high-performance liquid chromatography (RP-HPLC) and liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI MS/MS) for the first time. The inhibitory effects of the hydrolysates on the cell viabilities, cell cycles and apoptosis of breast cancer cells were evaluated with a cck8 kit and a flow cytometry. The result showed that YMC hydrolysates (YMCH) obtained by united hydrolyzation with trypsin (3 h) and alkaline protease (3 h) displayed the highest cell viability inhibition rate for MCF7 (20.74 ± 1.39%) and MDA-MB-231 (26.73 ± 2.87%) cells. Three peptides were identified in the RP-HPLC subfraction F3-4, and a nonapeptide (TPVVVPPFL) showed the most potent inhibitory effects on both cancer cells and displayed good gastrointestinal stability. TPVVVPPFL could induce G2-M cell cycle arrest in MCF7 cells and S cell arrest in MDA-MB-231 cells and induce apoptosis in both cancer cells. Moreover, in silico analysis indicated that the peptide had non-toxic and no inhibitory roles on P4502D6-enzyme. Together, this study shows that YMC is a good source of anti-breast cancer cells peptides.

Hydrolysis of peanut (Arachis hypogea L) protein concentrate by fungal crude protease extract: effect on structural, functional and in-vitro protein digestibility

Peanut protein concentrates (PPCs) were subjected to hydrolysis by crude protease extract (CPE) obtained from three fungi viz; Rhizopus oligosporus, Trichoderma reesei, and Aspergillus oryzae and the effect on structural, functional and in-vitro protein digestibility (IVPD) properties were studied. Particle size was found significantly (p ≤ 0.05) lower in hydrolyzed samples than un-treated samples. Fourier transform infrared spectroscopy (FTIR) spectrum of hydrolyzed samples displayed intense absorbance peaks in the wavelength ranging from 1500 to 2600 cm^-1. Peanut protein concentrates hydrolyzed by CPE from R. oligosporus showed higher surface hydrophobicity (564.18). Total sulfhydryl content was found lower in all the hydrolyzed samples whereas, reverse trend was observed for exposed sulfhydryl content. The structural changes simultaneously affected the functional and IVPD attributes of hydrolyzed PPCs. In comparison to the PPCs hydrolysed using crude extracts from T. reesei and R. oligosporus, PPCs hydrolysed by A, oryzae showed higher solubility, water and oil binding capacity, foaming capacity and foam stability. Higher IVPD values of 86.70% was also found in PPCs hydrolyzed with CPE of A. oryzae. The study established that CPE hydrolysis of PPCs has potential for scale-up studies and may serve as a cost effective alternative to protein hydrolysis with pure enzymes.

Characterization of Peanut Protein Hydrolysate and Structural Identification of Umami-Enhancing Peptides

Umami peptides are naturally found in various foods and have been proven to be essential components contributing to food taste. Defatted peanut powder hydrolysate produced by a multiprotease (Flavorzyme, Alcalase, and Protamex) was found to elicit an umami taste and umami-enhancing effect. The taste profiles, hydrolysis efficiency, amino acids, molecular weight distribution, Fourier transform infrared spectroscopy (FT-IR), and separation fractions obtained by ultrafiltration were evaluated. The results showed that peanut protein was extensively hydrolyzed to give mainly (up to 96.84%) free amino acids and peptides with low molecular weights (<1000 Da). Furthermore, β-sheets were the major secondary structure. Fractions of 1−3000 Da and <1000 Da prominently contributed to the umami taste and umami enhancement. To obtain umami-enhancing peptides, these two fractions were further purified by gel filtration chromatography, followed by sensory evaluation. These peptides were identified as ADSYRLP, DPLKY, EAFRVL, EFHNR, and SDLYVR by ultra-performance liquid chromatography (UPLC), and had estimated thresholds of 0.107, 0.164, 0.134, 0.148, and 0.132 mmol/L, respectively. According to the results of this work, defatted peanut powder hydrolysate had an umami taste and umami-enhancing effect, and is a potential excellent umami peptide precursor material for the food industry.

Albumin from Erythrina edulis (Pajuro) as a Promising Source of Multifunctional Peptides

Multifunctional peptides, capable of acting on different body systems through multiple mechanisms of action, offer many advantages over monofunctional peptides, including lower adverse side effects and costs. Erythrina edulis (pajuro) is a legume with a large number of high-quality proteins, of which their potential as a source of antioxidant peptides has been recently reported. In this study, the behavior of these proteins under a sequential enzymatic hydrolysis with digestive and microbial enzymes was investigated by evaluating the multi-functionality of the hydrolyzates. The albumin hydrolyzates obtained after the action of pepsin, pancreatin, and Alcalase showed antioxidant, angiotensin-converting enzyme (ACE), α-amylase, α-glucosidase, and dipeptidyl peptidase (DPP)-IV inhibitory activities. The radical scavenging properties of the hydrolyzate could be responsible for the potent protective effects observed in FeSO4-induced neuroblastoma cells. The findings support the role of pajuro protein as an ingredient of functional foods or nutraceuticals for health promotion and the prevention of oxidative stress, hypertension, and metabolic alteration-associated chronic diseases.

Relationship between enzyme, peptides, amino acids, ion composition, and bitterness of the hydrolysates of Alaska pollock frame

Alaska pollock frame is a kind of byproduct that was rich in protein, amino acids, and mineral elements. However, the unfavorite bitterness may probably be produced in enzymatic processes. In this study, the bitterness accounted from the hydrolysates prepared by neutral proteases, alkaline proteases, papain, flavourzyme, and animal proteases, was investigated. The hydrolysis conditions, amino acids composition, metal ion composition, molecular weight distribution, and peptide composition of the hydrolysates were detected to figure out the relationship between bitterness and compositions of the hydrolysates. The hydrolysate digested by alkaline protease has the highest bitterness intensity, and that amino acids composition, peptide composition, and molecular weight distribution had a significant influence on the bitterness degree. Hydrophobic amino acids and alkaline amino acids, such as leucine, isoleucine, lysine, and so on are likely to contribute to the bitterness and molecular weight distribution of peptides that affect bitterness is mainly lower than 3,000 Da. PRACTICAL APPLICATIONS: Fish bones would produce a bitter taste when reusing them by hydrolysis. Bitterness is one of unfavorable flavor as to consumers. The results of this study are of great significance for the further utilization of Alaska pollock frame. For products obtained from the hydrolysate of Alaska pollock frame, such as condiments and health care product the results of this study provide the processing technology of the lowest bitter hydrolysate, which can effectively improve the flavor and acceptability of the products.

Protective Effect of Chickpea Protein Hydrolysates on Colon Carcinogenesis Associated With a Hypercaloric Diet

OBJECTIVE

Colon cancer occupies the third place in incidence worldwide; eating habits, in particular, consumption of hypercaloric diets, are relevant in its etiopathogenesis. On the other hand, foods can also modulate carcinogenesis: for example, proteins, which when hydrolyzed release peptides with biological activities, and legumes, especially, chickpea, represent a good source of hydrolysates. The objective of this work was to verify the inhibitory effect of chickpea hydrolyzed protein on azoxymethane (AOM)-induced carcinogenesis in mice fed a hypercaloric diet.

METHODS

We hydrolyzed chickpea protein by pepsin, pancreatin, and a combined pepsin-pancreatin system, to test its anticarcinogenic and hypercaloric activity in mice that had consumed a hypercaloric diet or a normal diet but were injected with azoxymethane (AOM).

RESULTS

A concentrate (70% proteins) was obtained from chickpea seeds (18.5% proteins), and extensive hydrolysates were obtained at 15 minutes, in all tested enzyme systems. The greatest activity was evidenced in the hydrolysates obtained with pepsin-pancreatin at 90 minutes. Animals that consumed the hypercaloric diet had a higher concentration of cholesterol and a higher atherogenic index, which were significantly reduced with the administration of chickpea protein hydrolysates with a dose-response effect (10, 20, or 30 mg/kg), whereas no effect was observed in animals that consumed the normal diet. In animals given AOM, aberrant crypts were observed, at a higher rate in animals that consumed the hypercaloric diet; with the consumption of hydrolysates by the animals that consumed either diet, the number of aberrant crypts was reduced with the 3 doses tested, and the effect was better in those animals fed the hypercaloric diet. The best effect in all tests was with 30 mg/kg body weight.

CONCLUSION

The consumption of chickpea protein hydrolysates might confer a protective effect against colon carcinogenesis.

Preparation of the rainbow trout bone peptides directed by nutritional properties and flavor analyses

Rainbow trout bone proteins were prepared by heating at 121°C for 30 min, followed by filtration, concentration, and lyophilization. Nutritional properties and flavor analyses of hydrolysates digested by five different enzymes were investigated, respectively. Results showed that the crude protein content of rainbow trout bone was 15.90% and had a well-balanced nutritional value. The content of total amino acids was 983.64 mg/g. The amount of free amino acids of hydrolysates digested by alkaline protease, neutral protease, flavourzyme, papain, and trypsin for 3 hr was 207.83, 224.13, 1,001.59, 283.26, and 303.64 mg/g, respectively. During the hydrolysis, the main flavor compounds were identified by GC-MS to be alcohols, aldehydes, ketones, acids, and alkanes. After hydrolysis, the main molecular weight of peptides was focused on the range of 1,000-3,000 Da in all enzymatic hydrolysates. This study provided a theoretical basis to comprehensive utilization of rainbow trout bone in food industry.

Antioxidant and Chelating Activity of NontoxicJatropha curcasL. Protein Hydrolysates Produced byIn VitroDigestion Using Pepsin and Pancreatin

The antioxidant and metal chelating activities inJ. curcasprotein hydrolysates have been determined. The hydrolysates were produced by treatment of a nontoxic genotype with the digestive enzymes pepsin and pancreatin and then were characterized by fast protein liquid chromatography and reverse phase chromatography. Peptidic fractions with higher radical scavenging activity were analysed by matrix-assisted laser desorption/ionization mass spectrometry. The antioxidant activity was determined by measuring inhibition of the oxidative degradation ofβ-carotene and by measuring the reactive oxygen species (ROS) in Caco-2 cell cultures. Cu2+and Fe2+chelating activities were also determined. The hydrolysates inhibited the degradation ofβ-carotene and the formation of ROS in Caco-2 cells. The lower molecular weight peptidic fractions from FPLC had stronger antioxidant activity in cell cultures compared with the hydrolysates, which correlated with a higher content in antioxidant and chelating amino acids. These fractions were characterized by a large presence of peptides with different molecular masses. The hydrolysates exhibited both Cu2+and Fe2+chelating activity. It was concluded thatJ. curcasis a good source of antioxidant and metal chelating peptides, which may have a positive impact on the economic value of this crop, as a potential source of food functional components.

Mechanism of the discrepancy in the enzymatic hydrolysis efficiency between defatted peanut flour and peanut protein isolate by Flavorzyme

Both defatted peanut flour (DPF) and peanut protein isolate (PPI) are widely used to prepare peanut protein hydrolysates. To compare their enzymatic hydrolysis efficiencies, DPF and PPI were hydrolysed by Alcalase, Neutrase, Papain, Protamex and Flavorzyme. Alcalase and Flavorzyme were found to be the most efficient proteases to hydrolyse both DPF and PPI. The efficiency was comparable to each other when using Alcalase, while PPI was hydrolysed less efficiently than DPF when using Flavorzyme. Analysis of changes in the protein solubility, subunit and conformation, and amino acid composition of DPF, PPI and their Flavorzyme hydrolysis residues indicated that the PPI preparation process had minimal effect on it, but peptide aggregation via non-covalent bonding (including hydrophobic interactions and hydrogen bonds) during hydrolysis and/or thermal treatment after hydrolysis were likely responsible for the reduced hydrolysis efficiency of PPI by Flavorzyme.

Development of a novel method for hot-pressure extraction of protein from chicken bone and the effect of enzymatic hydrolysis on the extracts

To investigate the hot-pressure extraction of protein from chicken bone (CB), chicken bone extracts (CBE) was prepared from CB by heating at 130±0.5 °C for 120 min, followed by filtration, standing, defatting, and concentration. Effects of enzymatic hydrolysis on the properties of hydrolysates were examined. Results showed CBE contained 25.59% of protein, and showed a desirable value of protein digestibility-corrected amino acid score for adult. The total amino acid (AA) content of CBE is 21.99%, among which 40.62% and 54.66% are essential and fresh AA, respectively. Forty kinds of volatile compounds were identified after 24 h of hydrolysis, with 2,3,5-trimethylpyrazine as the key flavor compound. After 8 h of hydrolysis of CBE, the content of small MW of peptides (400-1000 Da) increased by 74 times compared with that of 1 h. CBE and its hydrolysates demonstrate a new kind of potential suitable nutritional supplement in various foods.

Comparison of in vitro digestion characteristics and antioxidant activity of hot- and cold-pressed peanut meals

Due to the poor protein solubility, hot-pressed peanut meal (HPM) has less value than cold-pressed peanut meal (CPM) in the food industry. The objective of this study was to determine whether the denatured proteins in HPM were suitable for hydrolysis by digestive enzymes. The hydrolysis characteristics and antioxidant activity of HPM and CPM during in vitro digestion were compared. The results showed that HPM was hydrolysed more extensively than CPM. There were more free amino acids and small peptides with MW<5 kDa in HPM hydrolysates. In addition, HPM hydrolysates displayed stronger 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,20-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical-scavenging activities, ORAC value and reducing power than CPM hydrolysates, which could be due to the higher content of small peptides, antioxidative amino acids and melanoidins in HPM hydrolysates. The above results indicated that HPM was a potential source of protein supplement for human consumption.

Potential use of peanut by-products in food processing: a review

Peanut is one of the most important oil and protein producing crops in the world. Yet the amounts of peanut processing by-products containing proteins, fiber and polyphenolics are staggering. With the environmental awareness and scarcity of space for landfilling, wastes/by-product utilization has become an attractive alternative to disposal. Several peanut by-products are produced from crush peanut processes and harvested peanut, including peanut meal, peanut skin, peanut hull and peanut vine. Some of peanut by-products/waste materials could possibility be used in food processing industry, The by-products of peanut contain many functional compounds, such as protein, fiber and polyphenolics, which can be incorporated into processed foods to serve as functional ingredients. This paper briefly describes various peanut by-products produced, as well as current best recovering and recycling use options for these peanut byproducts. Materials, productions, properties, potential applications in food manufacture of emerging materials, as well as environmental impact are also briefly discussed.

Biochemical properties of recombinant leucine aminopeptidase II from Bacillus stearothermophilus and potential applications in the hydrolysis of Chinese anchovy (Engraulis japonicus) proteins

The effects of various factors on the activity and conformation of recombinant leucine aminopeptidase II (rLAP II) from Bacillus stearothermophilus and its potential utilization in the hydrolysis of anchovy proteins were investigated. The optimal temperature and pH of rLAP II were 55 °C and 8.0 in phosphate buffer, and its activity was strongly stimulated by Co(2+). Conformational studies indicated that maintaining the α-helical structure had a critical effect on rLAP II activity. rLAP II was used to hydrolyze anchovy proteins, and it exhibited high specificity for peptides with molecular weight between 6000 and 1000 Da and positive coordination with endogenous enzymes and commercial Flavourzyme. Its use will enhance protein hydrolysis in species of aquatic animals. rLAP II could potentially be used to remove bitterness in the protein hydrolysis industry.

Biochemical properties and potential applications of recombinant leucine aminopeptidase from Bacillus kaustophilus CCRC 11223

Experiments were carried out to investigate the effects of various factors on the activity and conformation of recombinant leucine aminopeptidase of Bacillus kaustophilus CCRC 11223 (BkLAP) and potential utilization of BkLAP in the hydrolysis of anchovy protein. Optimal temperature and pH of BkLAP were 70 °C and 8.0 in potassium-phosphate buffer, respectively, and the activity was strongly stimulated by Ni²⁺, followed by Mn²⁺ and Co²⁺. Conformational studies via circular dichroism spectroscopy indicated that various factors could influence the secondary structure of BkLAP to different extents and further induce the changes in enzymatic activity. The secondary structure of BkLAP was slightly modified by Ni²⁺ at the concentration of 1×10⁻⁴ M, however, significant changes on the secondary structures of the enzyme were observed when Hg²⁺ was added to the concentration of 1×10⁻⁴ M. The potential application of BkLAP was evaluated through combination with the commercial or endogenous enzyme to hydrolysis the anchovy protein. Results showed that combining the BkLAP with other enzymes could significantly increase the degree of hydrolysis and amino acid component of hydrolysate. In this regard, BkLAP is a potential enzyme that can be used in the protein hydrolysate industry.