High-pressure microfluidisation positively impacts structural properties and improves functional characteristics of almond proteins obtained from almond meal

Almond protein isolate (API) obtained from almond meal was processed using dynamic high-pressure microfluidisation (0, 40, 80, 120, and 160 MPa pressure; single pass). Microfluidisation caused significant reductions in the particle size and increased absolute zeta potential. SDS-PAGE analysis indicated reduction in band intensity and the complete disappearance of bands beyond 80 MPa. Structural analysis (by circular dichroism, UV-Vis, and intrinsic-fluorescence spectra) of the API revealed disaggregation (up to 80 MPa) and then re-aggregation beyond 80 MPa. Significant increments in protein digestibility (1.16-fold) and the protein digestibility corrected amino acid score (PDCAAS; 1.15-fold) were observed for the API (80 MPa) than control. Furthermore, significant improvements (P < 0.05) in the functional properties were observed, viz., the antioxidant activity, protein solubility, and emulsifying properties. Overall, the results revealed that moderate microfluidisation treatment (80 MPa) is an effective and sustainable technique for enhancing physico-chemical and functional attributes of API, thus potentially enabling its functional food/nutraceuticals application.

Protein hydrolysates prepared by Alcalase using ultrasound and microwave pretreated almond meal and their characterization

The study aimed to optimize ultrasonic (US: 40 kHz/200 W for 10, 20, 30, 40, and 50 min), and microwave (MW: 160 W for 45, 90, 125, 180, and 225 s) pretreatment conditions on protein extraction yield and degree of protein hydrolysis (DH) from almond de-oiled meal, an industrial by-product. First order model was used to describe the kinetics of almond protein hydrolysates obtained with Alcalase. The highest DH, 10.95% was recorded for the US-50 min and 8.87% for MW-45 s; while it was 5.76% for the untreated/control sample. At these optimized pretreatment conditions, a 1.16- and 1.18-fold increment in protein recovery was observed for the US and MW pretreatments, respectively in comparison to the conventional alkaline extraction. The molecular weight distribution recorded for pretreated samples disclosed a significant reduction in the band thickness in comparison with control. Both the pretreatments resulted in a significant increase (P < 0.05) in the antioxidant activity, and TCA solubility index when compared with the control. Results evinced that US and/or MW pretreatments before enzymatic hydrolysis can be a promising approach for the valorization of almond meal for its subsequent use as an ingredient for functional foods/nutraceuticals which otherwise fetches low value as an animal feed.

A comparative study on comprehensive nutritional profiling of indigenous non-bio-fortified and bio-fortified varieties and bio-fortified hybrids of pearl millets

Seven indigenous pearl millet varieties, including non-bio-fortified (HC-10 & HC-20) and bio-fortified (Dhanashakti) and bio-fortified hybrids, viz., AHB-1200, HHB-299, HHB-311, and RHB-233, were studied in the present work. There was not any significant difference observed in the crucial anti-nutrients content, i.e., phytate (24.88-32.56 mg/g), tannin (3.07-4.35 mg/g), and oxalate (0.33-0.43 mg/g). Phytochemical content and antioxidant activity showed significantly high (p < 0.05) TPC and FRAP, TFC, and DPPH radical scavenging activity in the HHB 299 and Dhanashakti, respectively. Quantitative analysis of polyphenols by HPLC (first report on these varieties) revealed that HHB-299 has the highest amount of gallic acid. Fatty acid profiling by GC-FID showed that Dhanashakti, AHB-1200, and HHB-299 have rich monounsaturated fatty acid (MUFA) and polyunsaturated fatty acids (PUFA). Mineral analysis by ICP-OES showed high iron (87.79 and 84.26 mg/kg) and zinc (55.05 and 52.43 mg/kg) content in the HHB-311 and Dhanashakti, respectively. Results of the present study would help facilitate the formulation of various processed functional food products (RTC/RTE) that are currently not reported/unavailable.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05452-x.

Antioxidant potential and amino acid profile of ultrafiltration derived peptide fractions of spent hen meat protein hydrolysate

Spent hen meat is considered as a category of waste generated by the poultry sector which can lead to serious environmental concerns if not disposed and utilized properly. In this work, spent hen meat was hydrolysed by 2% Flavourzyme (6.5 pH, 55 °C) followed by ultrafiltration to produce three peptide fractions with molecular weights > 10 kDa, 5-10 kDa and < 5 kDa. These fractions were evaluated for antioxidant potential, SDS PAGE and amino acid profile. The SDS PAGE profile demonstrated bands in the low molecular weight (< 10 kDa) region. Peptide fractions of < 5 kDa exhibited highest antioxidant activity and, essential as well as hydrophobic amino acid composition than whole hydrolysate and other peptide fractions. Incorporation of the identified hydrolysate fraction in food could improve its shelf stability while serving as a preventive component against human degenerative diseases.

Bioactive peptides from meat: Current status on production, biological activity, safety, and regulatory framework

By-products of the meat processing industry which are often discarded as waste are excellent protein substrates for producing bioactive peptides through enzymatic hydrolysis. These peptides have tremendous potential for the development of functional food products but there is scanty information about the regulations on bioactive peptides or products in various parts of the world. This review focuses on the diverse bioactive peptides identified from different meat and meat by-products, their bioactivity and challenges associated in their production as well as factors limiting their effective commercialization. Furthermore, this report provides additional information on the possible toxic peptides formed during production of the bioactive peptides, which enables delineation of associated safety and risk. The regulatory framework in place for bioactive peptide-based foods in different jurisdictions and the future research directions are also discussed. Uniform quality, high cost, poor sensory acceptance, lack of toxicological studies and clinical evidence, paltry stability, and lack of bioavailability data are some of the key challenges hindering commercial advancement of bioactive peptide-based functional foods. Absorption, distribution, metabolism and excretion (ADME) studies in rodents, in vitro genotoxicity, and immunogenicity data could be considered as absolute pre-requisites to ensure safety of bioactive peptides. In the absence of ADME and genotoxicity data, long term usage to evaluate safety is highly warranted. Differences in legislations among countries pose challenge in the international trade of bioactive peptides-based functional foods. Harmonization of regulations could be a way out and hence further research in this area is encouraged.

Critical overview of biorefinery approaches for valorization of protein rich tree nut oil industry by-product

This review explores reutilization opportunities of protein-rich bio-waste derived from the major tree nuts (almonds, walnuts, and cashew nuts) oil processing industries through biorefinery strategies. The mechanically pressed out oil cakes of these nuts have high protein (45-55%), carbohydrate (30-35%), and fiber that could be utilized to produce bioactive peptides, biofuels, and dietary fiber, respectively; all of which can fetch substantially greater value than its current utilization as a cattle feed. Specific attention has been given to the production, characterization, and application of nut-based de-oiled cake hydrolysates for therapeutic benefits including antioxidant, antihypertensive and neuroprotective properties. The often-neglected safety/toxicological evaluation of the hydrolysates/peptide sequences has also been described. Based on the available data, it is concluded that enzymatic hydrolysis is a preferred method than microbial fermentation for the value addition of de-oiled tree nut cakes. Further, critical insights on the existing literature as well as potential research ideas have also been proposed.

Application of Aloe vera Gel Coating Enriched with Cinnamon and Rosehip Oils to Maintain Quality and Extend Shelf Life of Pomegranate Arils

A completely randomized design was applied on pomegranate arils for several post-harvest treatments before the packaging in polypropylene boxes for 15 days at (5 ± 1 °C, 95 ± 2% RH): control (untreated), Aloe vera gel (10% or 20%), 10% Aloe vera + rosehip oil (0.25% or 0.50%), 20% Aloe vera + rosehip oil (0.25% or 0.50%), 10% Aloe vera + cinnamon oil (0.25% or 0.50%), and 20% Aloe vera + cinnamon oil (0.25% or 0.50%). Aloe vera in combination with cinnamon oil resulted in an enhanced shelf life (15 d) compared to the uncoated arils (control). The Aloe vera + cinnamon oil coating led to the retention of total phenolics, anthocyanin, ascorbic acid, and antioxidant activity in context to the quality attributes. Moreover, this coating showed minimal change in the color, total soluble solids, titratable acidity, firmness, delayed ethylene production, respiration rate, and physiological weight loss. Also, A. vera + cinnamon oil coatings significantly (p < 0.05) inhibited the total counts of mesophilic aerobics, coliforms, and yeast and mold. Organoleptic attributes, including color, flavor, aroma, texture, and purchase acceptability were higher for the arils that were treated with 10% A. vera + 0.25% cinnamon oil; thus, this highly economical and easily available coating material can be formulated and used commercially to extend the shelf life and enhance the profit of the producers and/or processors.

Persistent organic pollutants in foods, their interplay with gut microbiota and resultant toxicity

Persistent Organic Pollutants (POPs) have become immensely prevalent in the environment as a result of their unique chemical properties (persistent, semi-volatile and bioaccumulative nature). Their occurrence in the soil, water and subsequently in food has become a matter of concern. With food being one of the major sources of exposure, the detrimental impact of these chemicals on the gut microbiome is inevitable. The gut microbiome is considered as an important integrant for human health. It participates in various physiological, biochemical and immunological activities; thus, affects the metabolism and physiology of the host. A myriad of studies have corroborated an association between POP-induced gut microbial dysbiosis and prevalence of disorders. For instance, ingestion of polychlorinated biphenyls, polybrominated diphenyl ethers or organochlorine pesticides influenced bile acid metabolism via alteration of bile salt hydrolase activity of Lactobacillus, Clostridium or Bacteroides genus. At the same time, some chemicals such as DDE have the potential to elevate Proteobacteria and Firmicutes/Bacteriodetes ratio influencing their metabolic activity leading to enhanced short-chain fatty acid synthesis, ensuing obesity or a pre-diabetic state. This review highlights the impact of POPs exposure on the gut microbiota composition and metabolic activity, along with an account of its corresponding consequences on the host physiology. The critical role of gut microbiota in impeding the POPs excretion out of the body resulting in their prolonged exposure and consequently, enhanced degree of toxicity is also emphasized.

Polyphenols of Edible Macroalgae: Estimation of In Vitro Bio-Accessibility and Cytotoxicity, Quantification by LC-MS/MS and Potential Utilization as an Antimicrobial and Functional Food Ingredient

Macroalgae are a rich source of polyphenols, and their ingestion promotes various health benefits. However, information on factors contributing to health benefits such as antioxidants, antimicrobial properties, bioaccessibility, and cytotoxicity is less explored and often unavailable. Therefore, this study aims to investigate the above-mentioned parameters for the brown and green macroalgae Sargassum wightii and Ulva rigida, respectively, collected from the southeast coast of India. S. wightii exhibited higher antioxidant activity and moderate antimicrobial activity against major food pathogens in an agar well diffusion assay and in the broth microdilution method (MIC50 being <0.5 mg/mL for all microorganisms tested). Both macroalgae extracts exhibited significantly high bioaccessibility of polyphenols. To evaluate the safety of the extracts, in vitro cytotoxicity by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was carried out on the primary cells: mouse splenic lymphocytes. An almost complete decline in the cell viability was seen at considerably high concentration (50 mg/mL), expressing the reasonably high safety of the extracts. The extracts of both macroalgae were quantified for polyphenols, wherein fucoxanthin (9.27 ± 2.28 mg/kg DW) and phloroglucinol (17.96 ± 2.80 mg/kg DW) were found to be greater in the S. wightii apart from other phenolics, like gallic acid, quercetin, vanillin, and ferulic acid. The results signify the tremendous scope for the value addition of S. wightii through extraction and purification of polyphenols for its potential exploitation in functional foods and nutraceuticals or as an antimicrobial ingredient in active or smart packaging.

Nanofluid research advances: Preparation, characteristics and applications in food processing

There has been growing interest and substantial improvement in thermal processes for enhancing the heat transfer rate in food industry applications. The replacement of conventional heat transfer fluids with nanofluids is now being considered as a novel and emerging solution to the heat transfer problem of the food processing sector. This review covers state-of-the-art methods for production and application of these nanofluids with emphasis on the decontamination of liquid foods. The review also discusses the influence of processing conditions such as temperature and nanoparticle concentration on the thermal and viscous characteristics of the developed nanofluids. Further, the effect of these developed nanofluids on the quality attributes of food materials has also been reviewed and analyzed. Based on the current technological status, certain knowledge gaps in nanofluid research have been identified, including controlled (shape and size) and systematic experimental studies, stability of nanofluids with increasing thermal cycles, increasing the compatibility of base fluid to nanomaterials, and toxicity and environmental impact assessment.

Strategies and advances in the pretreatment of microalgal biomass

Modification of structural components, especially the cell wall, through adequate pretreatment strategies is critical to the bioconversion efficiency of algal biomass to biorefinery products. Over the years, several physical, physicochemical, chemical and green pretreatment methods have been developed to achieve maximum productivity of desirable by-products to sustain a circular bioeconomy. The effectiveness of the pretreatment methods is however, species specific due to diversity in the innate nature of the microalgal cell wall. This review provides a comprehensive overview of the most notable and promising pretreatment strategies for several microalgae species. Methods including the application of stress, ultrasound, electromagnetic fields, pressure, heat as well as chemical solvents (ionic liquids, supercritical fluids, deep eutectic solvents etc.) have been detailed and analyzed. Enzyme and hydrolytic microorganism based green pretreatment methods have also been reviewed. Metabolic engineering of microorganisms for product specificity and lower inhibitors can be a future breakthrough in microalgal pretreatment.

Nanoencapsulated curcumin emulsion utilizing milk cream as a potential vehicle by microfluidization: Bioaccessibility, cytotoxicity and physico-functional properties

Curcumin loaded milk cream emulsion was microfluidized at different pressures (50-200 MPa) and passes (1-4) using a full-factorial experimental design. Ultrasonicated and microfluidized emulsion was evaluated for particle size, morphological characteristics, antioxidant activity, rheological properties, bioaccessibility and cytotoxicity. Significant reduction was observed in the average particle size (358.2 nm) after microfluidization at 100 MPa/2nd pass. Transmission electron micrographs of the control (homogenized) and microfluidized (100 MPa/2nd pass) samples showed uniform distribution of fat globules in the microfluidized sample with partially dissolved curcumin particles (50-150 nm). Encapsulation efficiency of microfluidized emulsion was found to be significantly higher (97.88%) after processing as compared to control (91.21%). Two-fold (100%) increase in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and 25% increase in ferric-reducing antioxidant power (FRAP) was observed for microfluidized emulsions over control. Infrared spectrums of the emulsion exhibited shift in high intensity peaks indicating bond cleavage after microfluidization. After characterization, emulsions were subjected to in vitro digestion (oral, gastric and intestinal phase) to evaluate its bioaccessibility which was found to be remarkably increased by 30% after microfluidization. For assessing processing induced safety of the formulation, in vitro cytotoxicity of the microfluidized nanocurcumin emulsion was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on HepG2 cells, wherein high % of cell viability (>93%) was seen even at a dose as high as 900 µg/mL revealing no toxic effect of the processing technique (microfluidization). This study highlights the efficacy of microfluidization as a technique and that of milk cream as an inexpensive, yet potential vehicle for generating stable and bio-accessible nano-curcumin emulsion.

Comparative functional and spectroscopic analysis of spent hen meat hydrolysate by individual and combined treatment of microbial proteases

Simultaneous (Sm) and sequential (Sq) use of microbial proteases for the hydrolysis of spent hen/chicken meat from antioxidant potential perspective is relatively unexplored and requires attention. In this work, meat was hydrolyzed using Flavourzyme (Fz) and Alcalase (Ac), each at 1, 2, and 3% for 6 h as well as using both enzymes (at 2% each) in Sm and Sq treatment. Maximum attained %DPPH-RSA (Fz:68.25; Ac:77.18; Sm:59.82; and Sq:65.97) and FRAP (mM TEAC/g) values (Fz:3.77; Ac:2.56; Sm:2.54; and Sq:3.37) were measured as a function of hydrolysis time. The highest (23.38%) and lowest (10.68%) degree of hydrolysis (DH) was obtained with 3% Ac and 1% Fz, respectively. FTIR spectroscopy clearly revealed changes in the secondary structure of proteins. SDS PAGE profiling of hydrolysates showed that Fz produces low molecular weight peptides (2-75 kDa) as compared to Ac or its combination with Ac. As per the results of this study, Sq enzyme treatment is recommended for preparing spent hen meat hydrolysate with higher functional attributes for possible use as functional food/nutraceutical.

Fipronil induced oxidative stress involves alterations in SOD1 and catalase gene expression in male mice liver: Protection by vitamins E and C

In the present investigation, hepatic oxidative stress induced by fipronil was evaluated in male mice. We also investigated whether pretreatment with antioxidant vitamins E and C could protect mice against these effects. Several studies conducted in cell lines have shown fipronil as a potent oxidant; however, no information is available regarding its oxidative stress inducing potential in an animal model. Out of 8 mice groups, fipronil was administered to three groups at low, medium, and high dose based on its oral LD50 (2.5, 5, and 10 mg/kg). All three doses of fipronil caused a significant increase in the serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) level with concomitant increase in the absolute and relative weight of liver. High dose of fipronil caused significant down-regulation in the hepatic mRNA expression of superoxide dismutase 1 (SOD1) and catalase (0.412 ± 0.01 and 0.376 ± 0.05-fold, respectively) as well as an increase in the lipid peroxidation (LPO). Also, decrease in the activity of antioxidant enzymes; SOD, catalase, and glutathione-S-transferase (GST) and the content of nonantioxidant enzymes; glutathione and total thiol were recorded. Histopathological examination of liver revealed dose dependant changes such as severe fatty degeneration and vacuolation leading to hepatocellular necrosis. Prior administration of vitamin E or vitamin C against fipronil high dose caused decrease in lipid peroxidation and increased activity of antioxidant enzymes. Severe reduction observed in functional activities of antioxidant enzymes was aptly substantiated by down-regulation seen in their relative mRNA expression. Thus results of the present study imply that liver is an important target organ for fipronil and similar to in vitro reports, it induces oxidative stress in the mice liver, which in turn could be responsible for its hepatotoxic nature. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1147-1158, 2016.

Fipronil-induced genotoxicity and DNA damage in vivo: Protective effect of vitamin E

Fipronil, an insecticide of the phenylpyrazole class has been classified as a carcinogen by United States Environmental Protection Agency, yet very limited information is available about its genotoxic effects. Adult male and female animals were gavaged with various doses of fipronil (2.5, 12.5, and 25 mg/kg body weight (bw)) to evaluate micronucleus test (mice), chromosome aberration (CA), and comet assay (rats), respectively. Cyclophosphamide (40 mg/kg bw; intraperitoneal) was used as positive control. Another group of animals were pretreated with vitamin E orally (400 mg/kg bw) for 5 days prior to administration of fipronil (12.5 mg/kg). Fipronil exposure in both male and female mice caused significant increase in the frequency of micronuclei (MN) in polychromatic erythrocytes. Similarly, structural CAs in bone marrow cells and DNA damage in the lymphocytes was found to be significantly higher in the male and female rats exposed to fipronil as compared to their respective controls. The average degree of protection (male and female animals combined together) shown by pretreatment of vitamin E against fipronil-induced genotoxicity was 63.28%: CAs; 47.91%: MN formation; and 74.70%: DNA damage. Findings of this study demonstrate genotoxic nature of fipronil regardless of gender effect and documents protective role of vitamin E.

Fipronil induced oxidative stress in kidney and brain of mice: protective effect of vitamin E and vitamin C

Fipronil is a relatively new insecticide of the phenpyrazole group. Fipronil-induced effects on antioxidant system and oxidative stress biomarkers are yet to be studied in vivo. The present study was undertaken to evaluate fipronil-induced alterations in the blood biochemical markers and tissue antioxidant enzymes after oral exposure in mice and to explore possible protective effect of pre-treatment of antioxidant vitamins against these alterations. Mice were divided into eight groups containing control, test and amelioration groups. Mice in the test groups were exposed to different doses of fipronil, i.e., 2.5, 5 and 10 mg/kg bw, respectively for 28 days. Mice in the amelioration groups were treated with vitamin E or vitamin C (each at 100 mg/kg) 2 h prior to high dose (10 mg/kg) of fipronil. Fipronil exposure at three doses caused significant increase in the blood biochemical markers, lipid peroxidation and prominent histopathological alterations; while level of antioxidant enzymes was severely decreased both in kidney and brain tissues. Prior administration of vitamin E or vitamin C in the fipronil exposed mice led to decrease in lipid peroxidation and significant increase in activities of antioxidants, viz., glutathione, total thiol, superoxide dismutase and catalase. Vitamin E and vitamin C administration in fipronil exposed mice also improved histological architecture of the kidney and brain when compared with fipronil alone treated groups. Thus, results of the present study demonstrated that in vivo fipronil exposure induces oxidative stress and pre-treatment with vitamin E or C can protect mice against this oxidative insult.

Toxicopathological alterations induced by high dose dietary T-2 mycotoxin and its residue detection in Wistar rats

T-2 toxin is one of the most potent cytotoxic and food-borne mycotoxins. Most experimental studies on the T-2 toxin have been performed at extremely low doses (ppb level). However, several field reports of contaminated feed have shown concentration of T-2 toxin to be as high as ≥20 ppm. Therefore, the impact of high dose T-2 toxin (20 ppm) after subacute exposure was investigated in an experimental setup with respect to growth performance, oxidative stress, and detailed pathomorphology in young male Wistar rats. Furthermore, to see the effect of such a high dose on the accumulation of T-2 toxin, its residues in various organs were quantified by high-performance thin-layer chromatography (HPTLC). Apart from obvious clinical toxicosis, rats in the toxin-fed group showed significant hemato-biochemical alterations and increased levels of biological markers of oxidative stress with concomitant decrease in levels of serum and tissue catalase and superoxide dismutase. These alterations were strongly supported by histopathological changes, such as hyperkeratosis and hyperplasia of the squamous gastric mucosa, oxidative damage to hepatocytes, atrophy of the thymus and spleen, and overall decrease in the spermatogenic activity of testes. An economical, simple, reliable, and quick method for the detection and quantification of T-2 toxin residues by HPTLC is also reported here. No residual T-2 toxin was detected in any of the organs tested, suggesting that T-2 toxin does not accumulate in tissues even at such a high exposure level.

Immunotoxic effects of imidacloprid following 28 days of oral exposure in BALB/c mice

Imidacloprid, a neonicotinoid insecticide has been in use worldwide for several years in agriculture and veterinary medicine. It is possible that residue of this compound may be recycled in the food chain and thus information regarding effects from potential exposure to it is warranted. The objective of the present study was to evaluate immunotoxic effects of imidacloprid in female BALB/c mice. Imidacloprid was administered orally daily at 10, 5, or 2.5mg/kg over 28 days. Specific parameters of humoral and cellular immune response including hemagglutinating antibody (HA) titer to sheep red blood cells (SRBC; T-dependent antigen), delayed type hypersensitivity (DTH) response to SRBC, and T-lymphocyte proliferation in response to phytohemagglutinin (PHA) were evaluated. The results showed that imidacloprid at high dose, specifically suppressed cell-mediated immune response as was evident from decreased DTH response and decreased stimulation index of T-lymphocytes to PHA. At this dose, there were also prominent histopathological alterations in spleen and liver. Histopathological analysis of footpad sections of mice revealed dose-related suppression of DTH response. Imidacloprid at low dose of 2.5mg/kg/day did not produce any significant alterations in cellular and humoral immune response and it seemed to be an appropriate dose for assessment of 'no observable adverse effects level' for immunotoxicity in BALB/c mice. The results also indicated that imidacloprid has immunosuppressive effects at doses >5mg/kg, which could potentially be attributed to direct cytotoxic effects of IMD against T cells (particularly TH cells) and that long-term exposure could be detrimental to the immune system.