Bacterial cellulose (BC) is a water resistant and strong material for edible films. Previous studies have been conducted on edible films containing fruit purees, but not using BC. In this study, films with or without fruit (mango or guava) purees were prepared using different ratios of nanofibrillated BC (NFBC) to pectin. The addition of fruit purees increased water vapor permeability (in about 13-18 times), reduced tensile strength (in more than 90%) and modulus (in about 99%), and increased elongation (in about 13 times), due to plasticizing effects of fruit sugars and matrix dilution by the purees. The partial or total replacement of pectin with NFBC resulted in improved physical properties, making the films stronger, stiffer, more resistant to water, and with enhanced barrier to water vapor. Fruit containing films based on pectin are suggested for sachets, whereas applications for food wrapping or coating may benefit from the use of NFBC.

Mango kernels are used for the first time as a source of both starch and starch nanocrystals (SNC) for bionanocomposite films. The starch yield was 38.5%, whereas the SNC yield (from starch) is more than 30%. Bionanocomposite films are produced from mango kernel starch (MKS) and 0-10 wt% SNC, and the corresponding films are also obtained from commercial corn starch. The addition of 5% SNC to MKS films increases their tensile strength and modulus in about 90% and 120% respectively, and reduces their water vapor permeability in about 15%. On the other hand, the film elongation has been reduced to half the one for the unfilled film, and the opacity has been increased. When compared to the corresponding corn starch films, mango kernel starch films exhibited higher overall tensile strength and elastic modulus, as well as increased opacity.

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Starch’s crystalline structure and gelatinization temperature might facilitate or hinder its use. Ball milling has frequently been mentioned in the literature as a method for reducing starch size and as a more environmentally friendly way to change starch, such as by increasing surface area and reactivity, which has an impact on other starch properties. In this study, starch samples were milled for varying durations (1, 5, 10, 20, and 30 h) and at different starch-to-ball mass ratios (1:6 and 1:20). Microscopy and XRD revealed that prolonged milling resulted in effective fragmentation and a decrease in crystallinity of the starch granules. Increasing milling times resulted in an increase in amylose content. Rheology and thermal studies revealed that gelatinization temperatures dropped with milling duration and that viscosity and thixotropy were directly influenced. The samples milled for 10, 20, and 30 h at a ratio of 1:20 were the most fragmented and upon drying formed a transparent film at ambient temperature, because of the lower gelatinization temperature. Starch ball milling could lead to the use of this material in thermosensitive systems.