Content and Bioaccessibility of Minerals and Proteins in Fish-Bone Containing Side-Streams from Seafood Industries.

With the aim to upcycle fish side-streams, enzymatic hydrolysis is often applied to produce protein hydrolysates with bioactive properties or just as a protein source for food and feed. However, the production of hydrolysates generates a side-stream. For underutilized fish and fish backbone this side-stream will contain fish bones and make it rich in minerals. The aim of this study was to assess the relative bioaccessibility (using the standardized in vitro model INFOGEST 2.0) of minerals in a dietary supplement compared to bone powder generated after enzymatic hydrolysis of three different fish side-streams: undersized whole hake, cod and salmon backbones consisting of insoluble protein and bones. Differences in the bioaccessibility of protein between the powders were also investigated. The enzyme hydrolysis was carried out using different enzymes and hydrolysis conditions for the different fish side-streams. The content and bioaccessibility of protein and the minerals phosphorus (P), calcium (Ca), potassium (K) and magnesium (Mg) were measured to evaluate the potential of the powder as an ingredient in, e.g., dietary supplements. The bone powders contained bioaccessible proteins and minerals. Thus, new side-streams generated from enzymatic hydrolysis can have possible applications in the food sector due to bioaccessible proteins and minerals.

Production of Bioactive Peptides from Hake By-Catches: Optimization and Scale-Up of Enzymatic Hydrolysis Process.

Fish by-catches, along with other fish side-streams, were previously used as raw material for the production of fishmeal and fish oil but appropriate handling allows their use in more valuable options. The aim of this research was to valorize undersized hake (Merluccius merluccius) as a model of using fish by-catch from the Bay of Biscay to produce protein hydrolysates with bioactivities. Six enzymes, with different proteolytic activities (endo- or exoproteases) and specificities, were tested to produce protein hydrolysates. Products obtained with an endoprotease of serine resulted in the most promising results in terms of protein extraction yield (68%), with an average molecular weight of 2.5 kDa, and bioactivity yield (antioxidant activity = 88.5 mg TE antioxidant capacity/g fish protein; antihypertensive activity = 47% inhibition at 1 mg/mL). Then, process conditions for the use of this enzyme to produce bioactive products were optimized using Box-Behnken design. The most favorable process conditions (time = 2 h, solids = 50% and enzyme/substrate = 2% with respect to protein) were scaled up (from 0.5 L to 150 L reactor) to confirm laboratory scale and model forecasts. The results obtained in the pilot-scale testing matched the outcomes predicted by the model, confirming the technical viability of the proposed process.

Evaluation of Valorisation Strategies to Improve Spent Coffee Grounds' Nutritional Value as an Ingredient for Ruminants' Diets.

Lignin in animal diets is a limiting factor due to its low digestibility. This study assessed the effects of thermal or mechanical pre-treatments and enzymatic hydrolysis on spent coffee grounds' (SCG) nutritional value and digestibility. A first trial studied the effect of thermal pre-treatment and hydrolysis with removal of the liquid part and a second trial studied mechanical pre-treatment and hydrolysis with and without removal of the liquid part. Autoclaving did not improve the enzymatic performance nor the nutritional value. Hydrolysis reduced the digestibility of the solid phase and impaired its ruminal fermentation efficiency. Hydrolysates without removing the liquid part improved its nutritional value, but not compared with unprocessed SCG. Grinding increased crude protein and reduced crude fibre and protein, which led to greater fermentation and in vitro digestibility. Thus, grinding emerges as the most promising valorisation strategy to improve SCG nutritional characteristics and their use for animal feed, contributing to the circular economy.

Anti-Steatotic Effects of Chlorella vulgaris, Nannochloropsis gaditana and Gracilaria vermiculophylla Algae Extracts in AML-12 Hepatocytes.

Non-alcoholic fatty liver disease (NAFLD) is considered the most common chronic liver alteration whose prevalence is increasing in Western countries. Microalgae and macroalgae have attracted great interest due to the high content in bioactive compounds with beneficial effects on health. The aim of the present study is to assess the potential interest of extracts rich in proteins obtained from the microalgae Chlorella vulgaris and Nannochloropsis gaditana and the macroalga Gracilaria vermiculophylla in the prevention of lipid accumulation in AML-12 hepatocytes. Toxicity was not observed at any of the tested doses. Both microalgae and the macroalga were effective in preventing triglyceride accumulation, with Nannochloropsis gaditana being the most effective one. Although the three algae extracts were able to increase different catabolic pathways involved in triglyceride metabolism, the mechanisms underlying the anti-steatotic effect were different in each algae extract. In conclusion, the present study demonstrates that Chlorella vulgaris, Nannochloropsis gaditana and Gracilaria vermiculophylla extracts are able to partially prevent the accumulation of triglycerides induced by palmitic acid in cultured hepatocytes, a model used to mimic the steatosis induced in liver by dietary patterns rich in saturated fat.

Solid State Fermentation as a Tool to Stabilize and Improve Nutritive Value of Fruit and Vegetable Discards: Effect on Nutritional Composition, In Vitro Ruminal Fermentation and Organic Matter Digestibility.

This research aimed to evaluate in vitro organic matter digestibility, fermentation characteristics and methane production of fruit and vegetable discards processed by solid state fermentation (SSF) by Rhizopus sp. Mixtures were composed of approximately 28% citric fruits, 35% other fruits and 37% vegetables. Fruit and vegetables were processed and fermented to obtain a stabilized product. Nutritional characterization and in vitro ruminal fermentation tests were performed to determine the effect of fungal bioconversion on digestibility, end products and gas production kinetics. Results indicate that SSF reduced organic matter and reducing sugars, while it increased crude protein and neutral detergent fiber, acid detergent fiber and neutral detergent insoluble protein. The in vitro gas production showed that SSF led to a reduction of the organic matter digestibility (p < 0.001), short chain fatty acids (SCFA; p = 0.003) and CH4 (p = 0.002). SSF reduced the gas production from the insoluble fraction (p = 0.001), without modifying the production rate (p = 0.676) or the lag time (p = 0.574). Regarding SCFA profile, SSF increased acetic (p = 0.020) and decreased propionic (p = 0.004) and butyric (p = 0.006) acids proportions, increasing acetic to propionic (p = 0.008) and acetic plus butyric to propionic (p = 0.011) ratios. SSF succeeded in obtaining a stabilized material enriched in protein, but at the expense of a reduction of protein availability and organic matter digestibility. These changes should be considered before including them in a ruminant's rations.

Valorisation of fruit and vegetable discards by fungal submerged and solid-state fermentation for alternative feed ingredients production.

The present research describes an integral strategy for valorisation of fruit and vegetable discards (FVd) in feeding application, using solid-state fermentation (SSF) and submerged fermentation (SmF), for both solid and liquid fractions obtained during these by-products handle and processing, using a strain of Rhizopus sp. After SSF, fermented biomass had 1.9 times higher protein content (up to 20.2 ± 1.7% DM) than the original mass and an improved amino acid (AA) profile (45.7 ± 1.8% essential AAs). Fatty acid (FA) profile was also modified during fermentation process, with higher monounsaturated (MUFA) and lower polyunsaturated fatty acid (PUFA) percentage in the final product compared with initial substrate. Phenolic compound concentration was double in final biomass than in initial substrate (up to 8.9 ± 1.5 mg GAE/g DM) and fermented product had higher antioxidant activity (DPPH reduction of 81.3 ± 7.7% and TEAC of 3.6 ± 0.3 mg/g DM). Compared with previously reported results, fruit complementation with vegetables increased the available nitrogen and resulted in higher biomass production. The fruit and vegetable leachate (FVL) obtained by centrifugation was treated by SmF and led, per liter of substrate, to 10.6 ± 1.4 g of fungal biomass and 3.3 g protein after 7 days of fermentation. Obtained fungal biomass was rich in PUFAs (27.1 ± 7.2% of total FA) and had an AA profile comparable to soybean meal, with 45.3 ± 1.5% of essential amino acids (EAA). In conclusion, results demonstrate that combined solid and liquid fermentation is a successful strategy for FVd valorisation to produce valuable alternative feed ingredient due to their high protein and the well-balanced lipid content and amino acid profile.

Valorization of cheese whey and orange molasses for fungal biomass production by submerged fermentation with Rhizopus sp.

Submerged fermentation (SmF) is an attractive biotechnological option for waste treatment, generating fungal bioprotein from food industry by-products. Using different Rhizopus sp. strains as fermentation agents, this paper describes a global strategy to identify interactions between cultivation parameters (pH 4.75-7.75, 7.5-82.5 g/l glucose, 0.75-3.75 g/l nitrogen, incubation time up to 5 days) for valorization of food industry by-products. Selected parameters and/or their interactions are critical for most of the proposed resulting values, giving the opportunity to optimize the process depending on the objective and making an "in silico" pre-evaluation of the process conditions. SmF of orange molasses leads to a high biomass and protein yield (11.9 g biomass/l and 4.0 g protein/l), with 43.1 ± 0.1% of essential amino acids and chemical oxygen demand (COD) reduction of almost 50%. Experiments with cheese whey result in 76.3 ± 1.1% of glucose consumption and a biomass production of 5.6 ± 2.2 g/l with 48.9 ± 5.1% of essential amino acids. SmF of orange molasses and cheese whey could contribute to promoting a sustainable feed industry while reducing by-product treatment.