The commercial cellulose fibers and cellulose fibers extracted from rice and oat husks were analyzed by chemical composition, morphology, functional groups, crystallinity and thermal properties. The cellulose fibers from rice and oat husks were used to produce hydrogels with poly (vinyl alcohol). The fibers presented different structural, crystallinity, and thermal properties, depending on the cellulose source. The hydrogel from rice cellulose fibers had a network structure with a similar agglomeration sponge, with more homogeneous pores compared to the hydrogel from oat cellulose fibers. The hydrogels prepared from the cellulose extracted from rice and oat husks showed water absorption capacity of 141.6-392.1% and high opacity. The highest water absorption capacity and maximum stress the compression were presented by rice cellulose hydrogel at 25°C. These results show that the use of agro-industrial residues is promising for the biomaterial field, especially in the preparation of hydrogels.

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The aim of the present work was to fortify yogurt by adding a stripped weakfish (Cynoscion guatucupa) protein hydrolysate obtained with the enzyme Protamex and microencapsulated by spray drying, using maltodextrin (MD) as wall material. The effects on the physicochemical properties, syneresis, texture, viscoelasticity, antioxidant and ACE inhibitory activities of yogurt after 1 and 7 days of storage were evaluated. In addition, microbiological and sensory analyses were performed. Four yogurt formulations were prepared: control yogurt (without additives, YC), yogurt with MD (2.1%, YMD), with the free hydrolysate (1.4%, YH) and the microencapsulated hydrolysate (3.5%, YHEn). Yogurts to which free and microencapsulated hydrolysates were added presented similar characteristics, such as a slight reduction in pH and increased acidity, with a greater tendency to present a yellow color compared with the control yogurt. Moreover, they showed less syneresis, the lowest value being that of YHEn, which also showed a slight increase in cohesiveness and greater rheological stability after one week of storage. All yogurts showed high counts of the microorganisms used as starters. The hydrolysate presence in both forms resulted in yogurts with antioxidant activity and potent ACE-inhibitory activity, which were maintained after 7 days of storage. The incorporation of the hydrolysate in the microencapsulated form presented greater advantages than the direct incorporation, since encapsulation masked the fishy flavor of the hydrolysate, resulting in stable and sensorily acceptable yogurts with antioxidant and ACE inhibitory activities.

Alternatives to increase fruit shelf life without the addition of synthetic preservatives, such as the use of edible coatings incorporated with bioactive compounds, should be explored. This study evaluated the effects of edible coating with fish protein hydrolysate on the quality and shelf life of cherry tomatoes. The cherry tomatoes were divided into four treatments: Control; coated with glycerol (5%; w/v); coated with glycerol (5%; w/v) and added with protein hydrolysate (1%; w/v) and coated with glycerol (5%; w/v) and added with protein hydrolysate (2%; w/v). The coated or uncoated cherry tomatoes were evaluated at 0, 7, 14, 21, and 45 days of chilled or room temperature storage for color, weight loss, firmness, soluble solids, pH, and molds and yeasts. The microbiological data suggested the edible coating with protein hydrolysate has bioactivity because inhibited the proliferation of molds and yeasts. However, in the other analyses showed no superior shelf life compared to the control. Practical applications The edible coating containing natural bioactive compounds can be used as an alternative to synthetic preservatives.

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