Gel Properties and Structural Characteristics of Composite Gels of Soy Protein Isolate and Silver Carp Protein.

Problems with silver carp protein (SCP) include a strong fishy odor, low gel strength of SCP surimi, and susceptibility to gel degradation. The objective of this study was to improve the gel quality of SCP. The effects of the addition of native soy protein isolate (SPI) and SPI subjected to papain-restricted hydrolysis on the gel characteristics and structural features of SCP were studied. The ß-sheet structures in SPI increased after papain treatment. SPI treated with papain was crosslinked with SCP using glutamine transaminase (TG) to form a composite gel. Compared with the control, the addition of modified SPI increased the hardness, springiness, chewiness, cohesiveness, and water-holding capacity (WHC) of the protein gel (p < 0.05). In particular, the effects were most significant when the degree of SPI hydrolysis (DH) was 0.5% (i.e., gel sample M-2). The molecular force results demonstrated that hydrogen bonding, disulfide bonding, and hydrophobic association are important molecular forces in gel formation. The addition of the modified SPI increases the number of hydrogen bonds and the disulfide bonds. Scanning electron microscopy (SEM) analysis showed that the papain modifications allowed the formation of a composite gel with a complex, continuous, and uniform gel structure. However, the control of the DH is important as additional enzymatic hydrolysis of SPI decreased TG crosslinking. Overall, modified SPI has the potential to improve SCP gel texture and WHC.

Impact of adding goldenberry (Physalis peruviana L.) on some quality characteristics and bio-functional properties of pasteurized carrot (Daucus carota L.) nectar.

Goldenberry juice was added in ratios of 0% (T1), 20% (T2), 30% (T3), 40% (T4) and 50% (T5) to carrot juice. Then the blends were mixed with sucrose solution (1:1), and pasteurized at 98 °C for 2 min. The produced carrot-goldenberry nectars were analyzed for physicochemical, sensory and microbial characteristics, in comparison to the carrot nectar, during 28 days of a cold storage at 4 °C. Results showed that the addition of goldenberry juice significantly increased the levels of acidity, total soluble solids, ascorbic acid and total phenolic compounds along with antioxidant activity for all nectars when compared to the control carrot nectar (T1). In contrast, the levels of turbidity and ß-carotene were significantly decreased by the addition of goldenberry. For color parameters, both L* and a* values were significantly decreased, while b* values were significantly increased by the addition of goldenberry. Goldenberry improved the organoleptic properties of the carrot nectar, and reduced deterioration in these properties during storage. Moreover, the results of microbial analysis indicated that all nectars were microbiologically safe (counts of total aerobic count and yeast and mold were less than 1 log10 CFU/mL). The carrot-goldenberry nectar (T3) had the highest overall acceptability during storage time. The obtained results valorize exploiting of goldenberry juice in processed fruit products like jams, juices and syrups.

Chemical composition and nutritive value of lantana and sweet pepper seeds and nabak seed kernels.

UNLABELLED: Chemical analysis was carried out on lantana (Lantana camara) and sweet pepper (Capsicum annuum L.) seeds and nabak (Zizyphus spina-christi) seed kernels. The proximate analysis (on dry weight basis) of sweet pepper seeds, lantana seeds, and nabak seed kernels showed the following composition: moisture 70.95%, 17.27%, and 4.22%; ash 4.88%, 1.81%, and 3.51%; fat 19.57%, 11.0%, and 30.19%; crude protein 19.28%, 6.3%, and 38.2%; and carbohydrate 56.3%, 80.9%, and 28.1%, respectively. For minerals, potassium was the most abundant element, followed by phosphorus and sodium. Also, zinc, iron, copper, and manganese were detected. Analysis of amino acids revealed that the first limiting amino acid was valine, for both lantana and sweet pepper seeds, but it was threonine for nabak seed kernels. Antinutritional compounds, including, phytic acid, trypsin inhibitor, and tannins, were detected in all seeds. Results of fatty acid compositions showed that the major fatty acid was oleic acid in both lantana (48.73%) and nabak oils (53.25%), but it was linoleic acid in sweet pepper oil (71.55%). Moreover, the degree of unsaturation of these oils was close to that of common vegetable oils. In all oils, there was absorbance in the ultraviolet (UV)-B and UV-C ranges with potential for use as broad spectrum UV protectants. It can be inferred that the seeds investigated are good sources of crude fat, crude protein, ash, carbohydrate, and some minerals. Furthermore, the oil extracts could be useful as edible oils and for industrial applications. PRACTICAL APPLICATION: The nutritional composition of the investigated seeds suggested that they could be used to meet part of the nutritional requirements of animal feeds. Also, they could be regarded as good sources of food ingredients and as new sources of edible oils.