Functional and nutritional characteristics of proteins and lipids recovered by isoelectric processing of fish by-products and low-value fish: A review

Enzymatic Preparation, In-Depth Molecular Analysis, and In Vitro Digestion Simulation of Palmitoleic Acid (ω-7)-Enriched Fish Oil Triacylglycerols

In this study, an enzymatic reaction was developed for synthesizing pure triacylglycerols (TAG) with a high content of palmitoleic acid (POA) using fish byproduct oil. The characteristics of synthesized structural TAGs rich in POA (POA-TAG) were analyzed in detail through ultrahigh-performance liquid chromatography Q Exactive orbitrap mass spectrometry. Optimal conditions were thoroughly investigated and determined for reaction systems, including the use of Lipozyme TL IM and Novozym 435, 15 wt % lipase loading, substrate mass ratio of 1:3, and water content of 2.5 and 0.5 wt %, respectively, resulting in yields of 67.50 and 67.45% for POA-TAG, respectively. Multivariate statistical analysis revealed that TAG 16:1/16:1/20:4, TAG 16:1/16:1/16:1, TAG 16:1/16:1/18:1, and TAG 16:0/16:1/18:1 were the main variables in Lipozyme TL IM and Novozym 435 enzyme-catalyzed products under different water content conditions. Finally, the fate of POA-TAG across the gastrointestinal tract was simulated using an in vitro digestion model. The results showed that the maximum release of free fatty acids and apparent rate constants were 71.44% and 0.0347 s-1, respectively, for POA-TAG lipids, and the physical and structural characteristics during digestion depended on their microenvironments. These findings provide a theoretical basis for studying the rational design of POA-structural lipids and exploring the nutritional and functional benefits of POA products.

Maximizing crustaceans (shrimp, crab, and lobster) by-products value for optimum valorization practices: A comparative review of their active ingredients, extraction, bioprocesses and applications

BACKGROUND

The processing of the three major crustaceans (shrimp, lobster, and crab) is associated with inevitable by-products, high waste disposal costs, environmental and human health issues, loss of multiple biomaterials (chitin, protein hydrolysates, lipids, astaxanthin and minerals). Nowadays, these bioresources are underutilized owing to the lack of effective and standardized technologies to convert these materials into valued industrial forms.

AIM OF REVIEW

This review aims to provide a holistic overview of the various bioactive ingredients and applications within major crustaceans by-products. This review aims to compare various extraction methods in crustaceans by-products, which will aid identify a more workable platform to minimize waste disposal and maximize its value for best valorization practices.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The fully integrated applications (agriculture, food, cosmetics, pharmaceuticals, paper industries, etc.) of multiple biomaterials from crustaceans by-products are presented. The pros and cons of the various extraction methods, including chemical (acid and alkali), bioprocesses (enzymatic or fermentation), physical (microwave, ultrasound, hot water and carbonic acid process), solvent (ionic liquids, deep eutectic solvents, EDTA) and electrochemistry are detailed. The rapid development of corresponding biotechnological attempts present a simple, fast, effective, clean, and controllable bioprocess for the comprehensive utilization of crustacean waste that has yet to be applied at an industrial level. One feasible way for best valorization practices is to combine innovative extraction techniques with industrially applicable technologies to efficiently recover these valuable components.

Effect of a novel drying method based on supercritical carbon dioxide on the physicochemical properties of sorghum proteins

The aim of this research was to use supercritical carbon dioxide (SC-CO2) drying as a novel approach for generating sorghum protein concentrates/isolates with enhanced functional properties. Sorghum protein extracts were obtained from white whole-grain sorghum flour and were dried by two methods, namely, freeze-drying and SC-CO2 drying. The collected proteins were characterized for their morphology, color, crystallinity, surface hydrophobicity, emulsifying activity index (EAI), creaming index (CI), foaming capacity (FC), foaming stability (FS), protein solubility, chemical interactions, and viscosity. The SC-CO2-dried proteins exhibited higher porosity compared to the freeze-dried ones with smaller particle sizes (∼5.1 vs. 0.4 μm, respectively). The XRD patterns indicated that the SC-CO2-dried proteins had a lower crystallinity than the freeze-dried proteins. However, the surface hydrophobicities of the freeze-dried and SC-CO2-dried proteins were similar. The EAI results showed that the emulsifying activity of freeze-dried protein powder (40.6) was better than that of SC-CO2-dried protein powder (29.8). Nevertheless, the solubility of SC-CO2-dried proteins was higher than that of freeze-dried proteins in most of the pHs investigated. Overall, the proposed SC-CO2 drying method has the potential to generate porous protein powders with improved solubility that can be used in developing functional foods.

Sugar osmolyte inhibits and attenuates the fibrillogenesis in RNase A: An in vitro and in silico characterizations

Mechanisms of protein aggregation are of immense interest in therapeutic biology and neurodegenerative medicine. Biochemical processes within the living cell occur in a highly crowded environment. The phenomenon of macromolecular crowding affects the diffusional and conformational dynamics of proteins and modulates their folding. Macromolecular crowding is reported to cause protein aggregation in some cases, so it is a cause of concern as it leads to a plethora of neurodegenerative disorders and systemic amyloidosis. To divulge the mechanism of aggregation, it is imperative to study aggregation in well-characterized model proteins in the presence of macromolecular crowder. One such protein is ribonuclease A (RNase A), which deciphers neurotoxic function in humans; therefore we decided to explore the amyloid fibrillogenesis of this thermodynamically stable protein. To elucidate the impact of crowder, dextran-70 and its monomer glucose on the aggregation profile of RNase-A various techniques such as Absorbance, Fluorescence, Fourier Transforms Infrared, Dynamic Light Scattering and circular Dichroism spectroscopies along with imaging techniques like Atomic Force Microscopy and Transmission Electron Microscopy were employed. Thermal aggregation and fibrillation were further promoted by dextran-70 while glucose counteracted the effect of the crowding agent in a concentration-dependent manner. This study shows that glucose provides stability to the protein and prevents fibrillation. Intending to combat aggregation, which is the hallmark of numerous late-onset neurological disorders and systemic amyloidosis, this investigation unveils that naturally occurring osmolytes or other co-solutes can be further exploited in novel drug design strategies.

The proximate composition, amino acid profile, fatty acid content, and mineral content of scale flour from three fish species as potential feeds for fish fry

BACKGROUND

Fish scale waste is highly valued both as a functional food ingredient and a potential feed source for farmed fish. This study aimed to analyse the chemical composition, fatty acid profile, and mineral content in fish scale flour of Osphronemus (O) goramy, Cyprinus (C) carpio, and Oreochromis (O) niloticus as potential feed for fish fry.

METHODS

Fish scales were cleaned with 10% w/v NaCl solution at a ratio of 1:10 (w/w) for 24 hours at 4 °C. Agitation was used every eight hours to remove excess protein. Fish scales were evenly arranged in a cooker and cooked at 121 °C for 10 minutes with 15 psi pressure. After cooking, 100 grams of wet fish scales was dried at 50 °C for four hours. Dried fish scales were transformed into flour for proximate composition analysed via standard AOAC method, amino acid and fatty acid assessment employing HPLC and GC-MS, while mineral content was determined using AAS.

RESULTS

The examined fish scale flour from three species displayed significant variations in chemical components, amino acids, and minerals (p<0.01). Crude protein content spanned 49.52% to 72.94%, and fat content ranged from 0.11% to 0.23%. Magnesium levels varied between 767.82 mg/kg and 816.50 mg/kg, calcium content ranged from 3.54 mg/kg to 12.16 mg/kg, iron content was within 40.46 mg/kg to 44.10 mg/kg, and zinc content ranged from 45.80 mg/kg to 139.19 mg/kg. Predominantly, glycine emerged as the main free amino acid (FAA), varying from 13.70% to 16.08%, while histidine had the lowest content, at 0.39% to 0.71%. Conversely, fatty acid content was low in all species examined ranging from 6.73% to 9.48%.

CONCLUSIONS

Flour from three farmed fish types has potential for fish fry feed due to its chemical composition, amino acid, and mineral content. Further validation is needed for amino acid comparison to fish meal.

The proximate composition, amino acid profile, fatty acid content, and mineral content of scale flour from three fish species as potential feeds for fish fry

Background

Fish scale waste is highly valued both as a functional food ingredient and a potential feed source for farmed fish. This study aimed to analyse the chemical composition, fatty acid profile, and mineral content in fish scale flour of Osphronemus (O) goramy, Cyprinus (C) carpio, and Oreochromis (O) niloticus as potential feed for fish fry.

Methods

Fish scales were cleaned with 10% w/v NaCl solution at a ratio of 1:10 (w/w) for 24 hours at 4 °C. Agitation was used every eight hours to remove excess protein. Fish scales were evenly arranged in a cooker and cooked at 121 °C for 10 minutes with 15 psi pressure. After cooking, 100 grams of wet fish scales was dried at 50 °C for four hours. Dried fish scales were transformed into flour for proximate composition analysed via standard AOAC method, amino acid and fatty acid assessment employing HPLC and GC-MS, while mineral content was determined using AAS.

Results

The examined fish scale flour from three species displayed significant variations in chemical components, amino acids, and minerals (p<0.01). Crude protein content spanned 49.52% to 72.94%, and fat content ranged from 0.11% to 0.23%. Magnesium levels varied between 767.82 mg/kg and 816.50 mg/kg, calcium content ranged from 3.54 mg/kg to 12.16 mg/kg, iron content was within 40.46 mg/kg to 44.10 mg/kg, and zinc content ranged from 45.80 mg/kg to 139.19 mg/kg. Predominantly, glycine emerged as the main free amino acid (FAA), varying from 13.70% to 16.08%, while histidine had the lowest content, at 0.39% to 0.71%. Conversely, fatty acid content was low in all species examined ranging from 6.73% to 9.48%.

Conclusions

Flour from three farmed fish types has potential for fish fry feed due to its chemical composition, amino acid, and mineral content. Further validation is needed for amino acid comparison to fish meal.

Ultrasound-aided pH-shift processing for resource-smart valorization of salmon and herring side streams

The possibility of reducing the amount of fresh water used during alkaline the pH-shift processing of salmon head (SH) and herring frame (HF) was evaluated with ultrasound (US) as a tool to mitigate its negative effects on protein yield. The role of water ratio and US for homogenate viscosity, mass yield, crude composition, functional properties and lipid oxidation of the SH and HF protein isolates were also investigated. Applying US during the solubilization step of the pH-shift process completely compensated for the reduced protein yield coming from using 3 rather than 6 volumes of water for HF, but not for SH. Using US had no negative effect on the composition and protein functionality of the HF protein isolate. However, it slightly increased its level of secondary lipid oxidation products. Altogether, applying US during the pH-shift processing at low water ratios can be a promising solution for more resource-smart valorization of herring side streams.

Protein Characteristics and Bioactivity of Fish Protein Hydrolysates from Tra Catfish (Pangasius hypophthalmus) Side Stream Isolates

Enzymatic hydrolysis is a novel method to recover highly potent bioactive fish protein hydrolysates (FPHs) from fish processing side-streams. The common way of producing FPHs directly from fish side-streams may be inappropriate due to the excess of lipids and pro-oxidants, especially in lipid-rich streams, as obtained from Tra catfish. This study aimed to optimise the hydrolysis conditions for a commercial enzyme (Alcalase® 2.4 L) (enzyme concentrate, temperature, and time) in FPH production from the fish protein isolate obtained from Tra catfish dark muscle (DM-FPI) using the pH-shift method. The degree of hydrolysis (DH), protein recovery (PR), and antioxidant properties, including DPPH radical scavenging activity (DPPH-RSA) and total reducing power capacity (TRPC), were measured to evaluate the effects of the hydrolysis conditions on the FPHs. Optimal hydrolysis was obtained at an enzyme/substrate protein ratio of 3% (v/w) and a hydrolysis temperature of 50 °C for 3 h. The FPHs obtained from different substrates, including DM-FPI, abdominal cut-off (ACO) FPI, and head and backbone blend (HBB) FPI, had similar DHs under these optimum conditions, ranging from 22.5% to 24.0%. However, the FPH obtained from abdominal cut-off isolate (ACO-FPH) showed the highest PR of 81.5 ± 4.3% and the highest antioxidant properties, with a DPPH-RSA of 86.1 ± 1.6% and a TRPC of 6.4 ± 0.4 equivalent mg vitamin C/g protein. The resulting FPHs present a natural source of antioxidants with great potential for food applications, especially the ACO-FPH. In addition, all FPHs had excellent amino acid profiles, indicating strong potential for their use as supplements. Tra catfish protein-rich side-streams can thus be processed into high-value bioactive FPHs using Alcalase for human consumption.

Agri-Food Surplus, Waste and Loss as Sustainable Biobased Ingredients: A Review

Ensuring a sustainable supply of food for the world’s fast growing population is a major challenge in today’s economy, as modern lifestyle and increasing consumer concern with maintaining a balanced and nutritious diet is an important challenge for the agricultural sector worldwide. This market niche for healthier products, especially fruits and vegetables, has increased their production, consequently resulting in increased amounts of agri-food surplus, waste, and loss (SWL) generated during crop production, transportation, storage, and processing. Although many of these materials are not utilized, negatively affecting the environmental, economic, and social segments, they are a rich source of valuable compounds that could be used for different purposes, thus preventing the losses of natural resources and boosting a circular economy. This review aimed to give insights on the efficient management of agri-food SWL, considering conventional and emerging recovery and reuse techniques. Particularly, we explored and summarized the chemical composition of three worldwide cultivated and consumed vegetables (carrots, broccoli and lettuce) and evaluate the potential of their residues as a sustainable alternative for extracting value-added ingredients for the development of new biodynamic products.

Protein Recovery of Tra Catfish (Pangasius hypophthalmus) Protein-Rich Side Streams by the pH-Shift Method

Increasing protein demand has led to growing attention being given to the full utilization of proteins from side streams in industrial fish processing. In this study, proteins were recovered from three protein-rich side streams during Tra catfish (Pangasius hypophthalamus) processing (dark muscle; head-backbone; and abdominal cut-offs) by an optimized pH-shift process. Physicochemical characteristics of the resulting fish protein isolates (FPIs) were compared to industrial surimi from the same raw material batch. The pH had a significant influence on protein extraction, while extraction time and the ratio of the extraction solution to raw material had little effect on the protein and dry matter recoveries. Optimal protein extraction conditions were obtained at pH 12, a solvent to raw material ratio of 8, and an extraction duration of 150 min. The resulting FPI contained <10% of the fat and <15% of the ash of the raw material, while the FPI protein recovery was 83.0−88.9%, including a good amino acid profile. All FPIs had significantly higher protein content and lower lipid content than the surimi, indicating the high efficiency of using the pH-shift method to recover proteins from industrial Tra catfish side streams. The FPI made from abdominal cut-offs had high whiteness, increasing its potential for the development of a high-value product.

Improvement of Oil Valorization Extracted from Fish By-Products Using a Handheld near Infrared Spectrometer Coupled with Chemometrics

A handheld near infrared (NIR) spectrometer was used for on-site determination of the fatty acids (FAs) composition of industrial fish oils from fish by-products. Partial least square regression (PLSR) models were developed to correlate NIR spectra with the percentage of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs) and, among them, omega-3 (ω-3) and omega-6 (ω-6) FAs. In a first step, the data were divided into calibration validation datasets, obtaining good results regarding R² values, root mean square error of prediction (RMSEP) and bias. In a second step, all these data were used to create a new calibration, which was uploaded to the handheld device and tested with an external validation set in real time. Evaluation of the external test set for SFAs, MUFAs, PUFAs and ω-3 models showed promising results, with R² values of 0.98, 0.97, 0.97 and 0.99; RMSEP (%) of 0.94, 1.71, 1.11 and 0.98; and bias (%) values of −0.78, −0.12, −0.80 and −0.67, respectively. However, although ω-6 models achieved a good R² value (0.95), the obtained RMSEP was considered high (2.08%), and the bias was not acceptable (−1.76%). This was corrected by applying bias and slope correction (BSC), obtaining acceptable values of R² (0.95), RMSEP (1.09%) and bias (−0.05%). This work goes a step further in the technology readiness level (TRL) of handheld NIR sensor solutions for the fish by-product recovery industry.

Consumer Perception of the Circular Economy Concept Applied to the Food Domain: An Exploratory Approach

Every year, agri-food industries in industrialised countries produce approximately 1.3 billion tonnes of food loss and waste. The adoption of a circular economy policy has received special attention by the agri-food industries, allowing for the creation and development of new food products made of by-products that would otherwise be wasted or used for secondary applications. The present work, of an exploratory nature, aims to assess how consumers conceptualise the circular economy in order to identify consumer recognition of the use of by-products from the food industry to upcycle food products and to evaluate attitudes towards the circular economy. To this end, a mixed-methodology was applied to 340 participants. The first part was qualitative and used free word association to evaluate consumers’ conceptualisation of the circular economy and use of by-products as foods. Data were analysed by grouping the responses into exclusive and exhaustive categories and a correspondence analysis was also performed to originate perceptual maps. Additionally, a questionnaire was designed to evaluate major concepts and attitudes correlated with the circular economy. Data were reduced by principal component analysis (PCA) and participants grouped through clustering. Results showed that consumers understand circular economy as related mainly into Sustainability, Economy, and Circularity dimensions. Participants had great difficulty identifying the by-products used as foods or as food ingredients. From the quantitative data, four groups were identified based on the associations to the six principal components originated by the PCA. However, the results highlighted a very low association with all clusters of the Food Valorisation dimension within the concept of the circular economy, and also a lack of a clear understanding of consumers’ attitudes towards food products from the circular economy. Greater promotion and dissemination by the competent entities aimed at the general public may contribute towards greater integration, participation and acceptance of the circular economy concept for the upscaling of food by-products.

Characterization and potential strategies for the valorisation of the Southwest Atlantic butterfish (Stromateus brasiliensis)

The waste of fish resources constitutes a serious environmental problem that must be avoided. The valorisation of by-catch species and decreasing the discard rate constitute a more efficient and sustainable use of these marine biomasses. In this work, we characterize and propose different potential uses for Stromateus brasiliensis, another frequently discarded (≥ 90%) and poorly studied by-catch species captured in the South Atlantic Ocean (FAO 41) by trawler fishing fleets. Furthermore, in the case of this species, freezing and frozen storage of the whole fish is the only strategy currently employed for its exploitation. The results revealed that muscle from S. brasiliensis presented a high content of polyunsaturated fatty acids (20.34%) and that the concentrations of both total diacyl glyceryl ethers (2.41%) and heavy metals (Hg 0.038, Pb 0.006 and Cd 0.018 mg/kg) were below the established limits for safe human consumption. Likewise, the protein hydrolysates proved to be a good source of amino acids for human consumption or animal feeding. Minced muscle blocks could be made by a mechanical separation process of the flesh, and the composition of minced muscle did not differ much from that of the whole fish. Furthermore, this process allows the incorporation of cryoprotectants and antioxidants to extend the frozen shelf life of this fatty fish. An extraction process from mechanically mixed skin and bones yielded a good source of collagen that should not be neglected.

Protein Recovery from Underutilised Marine Bioresources for Product Development with Nutraceutical and Pharmaceutical Bioactivities

The global demand for dietary proteins and protein-derived products are projected to dramatically increase which cannot be met using traditional protein sources. Seafood processing by-products (SPBs) and microalgae are promising resources that can fill the demand gap for proteins and protein derivatives. Globally, 32 million tonnes of SPBs are estimated to be produced annually which represents an inexpensive resource for protein recovery while technical advantages in microalgal biomass production would yield secure protein supplies with minimal competition for arable land and freshwater resources. Moreover, these biomaterials are a rich source of proteins with high nutritional quality while protein hydrolysates and biopeptides derived from these marine proteins possess several useful bioactivities for commercial applications in multiple industries. Efficient utilisation of these marine biomaterials for protein recovery would not only supplement global demand and save natural bioresources but would also successfully address the financial and environmental burdens of biowaste, paving the way for greener production and a circular economy. This comprehensive review analyses the potential of using SPBs and microalgae for protein recovery and production critically assessing the feasibility of current and emerging technologies used for the process development. Nutritional quality, functionalities, and bioactivities of the extracted proteins and derived products together with their potential applications for commercial product development are also systematically summarised and discussed.

Food functionality of protein isolates extracted from Yellowfin Tuna (Thunnus albacares) roe using alkaline solubilization and acid precipitation process

Four types of roe protein isolates (RPIs) were prepared through the alkaline solubilization and acid precipitation (ASAP) process, and their functional properties and in vitro bioactivities were evaluated. Higher buffer capacity in pH-shift range of 8-12 was found in RPI-1 (pH 11/4.5), required average 94.5 mM NaOH than that of other RPIs to change the pH by 1 unit. All the samples of 1% dispersion (w/v) showed the lowest buffering capacity near the initial pH. The water-holding capacities (WHC) of RPIs and casein as controls without pH-shift were in range of 3.7-4.0 g/g protein, and there were no significant differences (p > 0.05). At pH 2 and 8-12 with pH-shift, WHC and protein solubility of RPIs were significantly improved compared to those of controls. Foaming capacities of RPI-1 and RPI-3 were 141.9% and 128.1%, respectively, but those of RPI-2 and RPI-4 were not detected. The oil-in-water emulsifying activity index of RPI-1 and RPI-3 was 10.0 and 8.3 m2/g protein, which was not statistically different from casein (7.0 m2/g), but lower than that of hemoglobin (19.1 m2/g). Overall, RPIs, casein, and hemoglobin exhibited lower food functionality at pH 4-6 near isoelectric points. Through the pH-shift treatment, the food functionalities of RPIs were improved over the controls, especially in the pH 2 and pH 8-12 ranges. RPI also showed in vitro antioxidant and antihypertensive activities. Therefore, it has been confirmed that RPI extracted from yellowfin tuna roe has high utility as a protein- or food-functional-enhancing material or protein substitute resource for noodles, confectionery, baking, and surimi-based products.

Acid and alkaline solubilization (pH shift) process: a better approach for the utilization of fish processing waste and by-products

Several technologies and methods have been developed over the years to address the environmental pollution and nutritional losses associated with the dumping of fish processing waste and low-cost fish and by-products. Despite the continuous efforts put in this field, none of the developed technologies was successful in addressing the issues due to various technical problems. To solve the problems associated with the fish processing waste and low-value fish and by-products, a process called pH shift/acid and alkaline solubilization process was developed. In this process, proteins are first solubilized using acid and alkali followed by precipitating them at their isoelectric pH to recover functional and stable protein isolates from underutilized fish species and by-products. Many studies were conducted using pH shift process to recover proteins from fish and fish by-products and found to be most successful in recovering proteins with increased yields than conventional surimi (three cycle washing) process and with good functional properties. In this paper, problems associated with conventional processing, advantages and principle of pH shift processing, effect of pH shift process on the quality and storage stability of recovered isolates, applications protein isolates, etc. are discussed in detail for better understanding.

Physicochemical evaluation of sausages prepared by lantern fish (Benthosema pterotum) protein isolate

The purpose of this study was to show how sausages produced with lantern fish (Benthosema pterotum) protein isolate at two levels 4% (sample A) and 2% (sample B), and then, the physicochemical and sensory properties of sausages (A and B) were determined during the storage (14, 30, and 60 days) at 4°C. Firstly, fish protein isolate (FPI) prepared at alkaline pH (12). It was found that the acidic value, peroxide value (PV), and thiobarbituric acid (TBA) value of sausages increased during the storage. The highest level of TBA value was found at the second month of storage as 0.51 mg malonaldehyde/kg. The PV and acidic value reached to 9.45 meq/kg and 4.82 at the end of storage, respectively. Moreover, the stiffness, adherence, and springiness were assessed by texture profile analysis which was found sausages containing FPI had stronger texture and structure compared to control sample. The SDS-PAGE analysis identified the proteins from 15.4 to 202.3 kDa, which exhibit no major differences in protein patterns of two types of sausages. Furthermore, sensory evaluation diagnostic was carried out in terms of the sensory attributes such as texture, flavor, odor, color, and overall acceptability, and the results indicated the greatest overall acceptability in samples containing 2% FPI.

Recovery and characterization of proteins from pangas (Pangasius pangasius) processing waste obtained through pH shift processing

Study was conducted to recover proteins from pangas (Pangasius pangasius) processing waste (fillet frames) using pH shift method and to characterize the recovered isolates. pH 2.0 from acidic range and pH 13.0 from alkaline range were found to have maximum protein recovery (p < 0.05). During the recovery process, acidic pH (pH 2.0) was found to have minimal effect on proteins resulting in more stable isolates and strong protein gels. Alkaline pH (pH 13.0) caused protein denaturation resulting in less stable proteins and poor gel network. Both acidic and alkaline-aided processing caused significant (p < 0.05) reductions in total lipid, myoglobin, and pigment content thus by resulting in whiter protein isolates and gels. The content of total essential amino acids increased during pH shift processing, indicating the enrichment of essential amino acids. No microbial counts were detected in any of the isolates prepared using acid and alkaline extraction methods. pH shift processing was found to be promising in the utilization of fish processing waste for the recovery of functional proteins from pangas processing waste thus by reducing the supply demand gap as well pollution problems.

Sequential extraction of gel-forming proteins, collagen and collagen hydrolysate from gutted silver carp (Hypophthalmichthys molitrix), a biorefinery approach

Collagen and collagen hydrolysate (CH) was recovered from the bone and skin containing sediment residue emerging during pH-shift-based protein isolation from silver carp. Hydrolysis resulted in higher yield (15.1-15.4%) compared to collagen isolation by acid or pepsin (3.1-5.9%) (p<0.05). Isolated collagens were characterized as type I and maintained their triple-helical structure, confirmed by SDS-PAGE and FTIR. Pepsin-hydrolysis and sequential hydrolysis by pepsin and trypsin hydrolyzed all heavy molecular weight chains of collagen but sequential hydrolysis yielded higher degree of hydrolysis. When CH was added to a silver carp protein isolate prior to gelation, the gel behavior was dependent on molecular weight of the added CH. More hydrolyzed collagen emerging from sequential hydrolysis improved water holding capacity of the gel while reducing its breaking force. Thus, residue from pH-shift processing of fish can be used for isolation of high quality collagen/CH and provides a promising basis for a multiple-product fish biorefinery.

Evaluation of the efficacy, safety and acceptability of a fish protein isolate in the nutrition of children under 36 months of age

OBJECTIVE

To determine the effect of a fish protein isolate (FPi), administered over 6 months, on the growth of children aged 6-36 months, measured by Z-scores of height-for-age (HAZ) and weight-for-height (WHZ), compared with the standard meal without FPi; and to determine the safety and acceptability of FPi daily consumption.

DESIGN

Cluster-randomized community-based controlled trial. For 6 months, the centres received either FPi replacing 50 % of total proteins in the diet or standard protein. HAZ and WHZ were used to determine the effect on growth. Acceptability was determined by daily consumption, measured by weighing the servings before and after consumption.

SETTING

Day care centres and community nutritional centres in northern Lima, Peru.

SUBJECTS

Children (n 441) aged 6-36 months.

RESULTS

Four centres were randomized to the intervention with FPi, five centres were randomized to the standard control diet. More than 36 900 meals were prepared and administered in a supervised manner. Both groups received the same amounts of energy and proteins daily (proteins about 12-15 % of total energy). Growth of children who received the FPi diet was similar to that of children with the standard diet. Consumption was similar in the FPi and control groups (70 v. 80 % of amount offered, respectively). The protein was safe and well tolerated. No adverse events were reported. However, the cost of the intervention with FPi was 20-40 % lower v. the standard diet with animal protein derived from beef, chicken, eggs or liver.

CONCLUSIONS

The FPi was well accepted and there was no significant difference in growth between both groups. FPi is a potential source of animal protein at lower cost.