Valorization of onion peel waste: From trash to treasure

Globally, fruits and vegetables are consumed as raw, processed, or as an additive, accounting for approximately 50% of total food wastage. Among the fruits and vegetables, onion is well known for its potential bioactive components; however, peels of onion are a major concern for the environmental health and food industries. Effective utilization methods for valorizing the onion peel should be needed to develop value-added products, which are more eco-friendly, cost-effective, and sustainable. Therefore, this review attempts to emphasize the conventional and emerging valorization techniques for onion peel waste to generate value-added products. Several vital applications including anticancerous, antiobesity, antimicrobial, and anti-inflammatory activities are thoroughly discussed. The findings showed that the use of advanced technologies like ultrasound-assisted extraction, microwave-assisted extraction, and enzymatic extraction, demonstrated improved extraction efficiency and higher yield of bioactive compounds, which showed the anticancerous, antiobesity, antimicrobial, and anti-inflammatory properties. However, in-depth studies are recommended to elucidate the mechanisms of action and potential synergistic effects of the bioactive compounds derived from onion peel waste, and to promote the sustainable utilization of onion peel waste in the long-term.

Utilization of shallot bio-waste (Allium cepa L. var. aggregatum) fractions for the production of functional cookies

Shallot harvesting and processing produce various waste streams, and the current study aims to investigate the effects of shallot bio-waste powder (SWP) substitution on different flour properties. Increased SWP to 50% substitution of stalk and petiole showed a rise in swelling capacity (43.33%) and water absorption (342.22%), and oil absorption (320.73%), respectively. Foaming capacity improved from 48.00% in control to 60.26% in 30% flower substitution and further decreases to 51.28% at 50%. Pasting properties reduced at higher SWP substitution and the highest drop in peak viscosity was observed at Stalk-50 (457.33 cP). Subsequently, developed functional cookies showed enhanced fiber, ash, total phenol, and total flavonoids with 3, 2, 7, and 5 fold, respectively. Cookies developed with higher substitution were of darker color and higher hardness and fracturability. Sensory evaluation with fuzzy analysis revealed better acceptance for stalk and petiole (10%) and peel (5%) of final cookies with elevated nutritional value.

Development of active packaging film from sodium alginate/carboxymethyl cellulose containing shallot waste extracts for anti-browning of fresh-cut produce

Owing to growing concerns about making pollution-free sustainable environment by reducing the dumping of agricultural waste and convert it into valuable product is a key to carry out the present study. The ultimate goal of this study is to convert onion solid wastes (OSWs) into active packaging and evaluating the anti-browning effect due to the OSWs holding rich polyphenols and antioxidants. The active packaging film was fabricated by using sodium alginate (SA) and carboxymethyl cellulose (CMC) along with SOWEs such as peel and stalk at 0.2% and 0.5% concentration. The film made with SA/CMC/SOWEs had good physical, mechanical, optical and barrier property, higher phenolic and antioxidant activity compared to control. In addition, the effect of SA/CMC/SOWEs film packaging on anti-browning and quality of fresh-cut apple and potato stored at 4 °C was studied. The results show the SA/CMC/SOWEs film had better effect on controlling browning index in fresh-cut apple and potato over the storage of 12 days and 5 days. This study concludes that the SA/CMC film developed with shallot stalk extract can be used for wrapping of fresh-cut fruits and vegetables. It also prevents browning and maintains the overall quality than control and shallot peel incorporated film.