Optimization of enzymatic hydrolysis for acid pretreated date seeds into fermentable sugars

Green extraction technologies for valorization of date seed waste to achieve sustainable development goals: Biofunctional and innovative food applications

Date processing industries generate substantial quantities of waste, including date seeds, which present disposal challenges and environmental concerns. Traditionally, date seed waste has been discarded through landfilling, open burning, or dumping, leading to soil, air, and water pollution. However, with increasing awareness of environmental sustainability and resource conservation, there is a growing interest in valorizing date seed waste using green extraction technologies and innovative food product development approaches for date seed valorization. Therefore, this review aims to explore the biochemical composition of date seeds and the application of green extraction technologies for recovering bioactive compounds. Moreover, this review focuseson the development of date seed-based functional foods, highlighting their applications in bakery, meat products, and beverages. Date seed waste contains both essential (e.g., amino acids, dietary fiber, minerals, etc.) and non-essential (e.g., phenolic compounds, oil, etc.) bioactive nutrients. Compared with traditional methods, green extraction technologies, such as ultrasound-assisted, microwave-assisted, sub or supercritical, enzymatic-assisted extraction, and microbial fermentation have significantly improved extraction efficiency. The incorporation of date seed in the development of breads, cookies, meat products, and beverages (date seed coffee and functional drinks) can enhance bioavailability, stability, and sensory attributes, while preserving the bio-functionality and health benefits. Moreover, date seed valorization can contribute to Sustainable Development Goals 2, 3, 12, and 13. In general, the utilization of date seed waste for the development of innovative food products presents a sustainable solution that is beneficial for both the environment and human health.

Optimisation of sugar and solid biofuel co-production from almond tree prunings by acid pretreatment and enzymatic hydrolysis

Almond pruning biomass is an important agricultural residue that has been scarcely studied for the co-production of sugars and solid biofuels. In this work, the production of monosaccharides from almond prunings was optimised by a two-step process scheme: pretreatment with dilute sulphuric acid (0.025 M, at 185.9-214.1 ℃ for 0.8-9.2 min) followed by enzyme saccharification of the pretreated cellulose. The application of a response surface methodology enabled the mathematical modelling of the process, establishing pretreatment conditions to maximise both the amount of sugar in the acid prehydrolysate (23.4 kg/100 kg raw material, at 195.7 ℃ for 3.5 min) and the enzymatic digestibility of the pretreated cellulose (45.4%, at 210.0 ℃ for 8.0 min). The highest overall sugar yield (36.8 kg/100 kg raw material, equivalent to 64.3% of all sugars in the feedstock) was obtained with a pretreatment carried out at 197.0 ℃ for 4.0 min. Under these conditions, moreover, the final solids showed better properties for thermochemical utilisation (22.0 MJ/kg heating value, 0.87% ash content, and 72.1 mg/g moisture adsorption capacity) compared to those of the original prunings.

Biotechnological enhancement of lactic acid conversion from pretreated palm kernel cake hydrolysate by Actinobacillus succinogenes 130Z

The aim of this study was to establish an improved pretreatment and fermentation method i.e. immobilized cells for high recovery of fermentable sugars from palm kernel cake (PKC) and its effects on fermentability performance by Actinobacillus succinogenes 130Z in the conversion of the fermentable sugar to lactic acid. The effects of oxalic acid concentrations (1-6% w/v) and residence times (1-5 h) on the sugar recovery were initially investigated and it was found that the highest mannose concentration was 25.1 g/L at the optimum hydrolysis conditions of 4 h and 3% (w/v) oxalic acid. The subsequent enzymatic saccharification of the pretreated PKC afforded the highest enzymatic digestibility with the recovered sugars amounting to 25.18 g/L and 9.14 g/L of mannose and glucose, respectively. Subsequently, the fermentability performance of PKC hydrolysate was evaluated and compared in terms of cultivation phases (i.e. mono and dual-phases), carbonate loadings (i.e. magnesium and sodium carbonates), and types of sugars (i.e. glucose and mannose). The highest titer of 19.4 g/L lactic acid was obtained from the fermentation involving A. succinogenes 130Z in dual-phase cultivation supplemented with 30 g/L of magnesium carbonate. Lactic acid production was further enhanced by using immobilized cells with coconut shell-activated carbon (CSAC) of different sizes (A, B, C, and D) in the repeated batch cultivation of dual-phase fermentation producing 31.64 g/L of lactic acid. This work sheds light on the possibilities to enhance the utilization of PKC for lactic acid production via immobilized A. succinogenes 130Z.

Optimization of Wheat Straw Conversion into Microbial Lipids by Lipomyces tetrasporus DSM 70314 from Bench to Pilot Scale

Microbial lipids are renewable platforms for several applications including biofuels, green chemicals, and nutraceuticals that can be produced from several residual carbon sources. Lignocellulosic biomasses are abundant raw materials for the production of second-generation sugars with conversion yields depending on the quality of the hydrolysates and the metabolic efficiency of the microorganisms. In the present work, wheat straw pre-treated by steam explosion and enzymatically hydrolysed was converted into microbial lipids by Lipomyces tetrasporus DSM 70314. The preliminary optimization of the enzymatic hydrolysis was performed at the bench scale through the response surface methodology (RSM). The fermentation medium and set-up were optimized in terms of the nitrogen (N) source and carbon-to-nitrogen (C/N) ratio yielding to the selection of soy flour as a N source and C/N ratio of 160. The bench scale settings were scaled-up and further optimized at the 10 L-scale and finally at the 50 L pilot scale bioreactor. Process optimization also included oxygen supply strategies. Under optimized conditions, a lipid concentration of 14.8 gL−1 was achieved corresponding to a 23.1% w/w lipid yield and 67.4% w/w lipid cell content. Oleic acid was the most abundant fatty acid with a percentage of 57%. The overall process mass balance was assessed for the production of biodiesel from wheat straw.

Review on the extraction of bioactive compounds and characterization of fruit industry by-products

The by-products produced from fruit processing industries could be a potential hazard to environmental pollution. However, these by-products contain several biologically active molecules (essential fatty acid, phenolic compounds, flavonoids, coloring pigments, pectin, proteins, dietary fibers, and vitamins), which can be utilized for various applications in the food, pharmaceutical, cosmetic and textile industries. Nevertheless, during extraction, these bioactive compounds' recovery must be maximized using proper extraction technologies, keeping both economy and environment under consideration. In addition, the characteristics of the extract obtained from those by-products depend mainly on the parameters considered during the extraction process. In this review, an overview of different technologies used to extract bioactive compounds from fruit industry by-products such as seeds and peels has been briefly discussed, along with their mechanisms, process, advantages, disadvantages, and process parameters. In addition, the characteristics of the extracted bioactive compounds have also been briefly discussed in this review.

Critical overview of biomass feedstocks as sustainable substrates for the production of polyhydroxybutyrate (PHB)

Polyhydroxybutyrates (PHBs) are a class of biopolymers produced by different microbial species and are biodegradable and biocompatible in nature as opposed to petrochemically derived plastics. PHBs have advanced applications in medical sector, packaging industries, nanotechnology and agriculture, among others. PHB is produced using various feedstocks such as glycerol, dairy wastes, agro-industrial wastes, food industry waste and sugars. Current focus on PHB research has been primarily on reducing the cost of production and, on downstream processing to isolate PHB from cells. Recent advancements to improve the productivity and quality of PHB include genetic modification of producer strain and modification of PHB by blending to develop desirable properties suited to diversified applications. Selection of feedstock plays a critical role in determining the economic feasibility and sustainability of the process. This review provides a bird's eye view of the suitability of different waste resources for producing polyhydroxybutyrate; providing state-of the art information and analysis.