Development of fiber-enriched muffins using pomegranate peel powder and its effect on physico-chemical properties and shelf life of the muffins.

BACKGROUND: Pomegranate peel is a by-product from the pomegranate processing industries and is a rich source of dietary fibers and bioactive compounds. It has good antioxidant and antimicrobial properties. In the present study, the effects of substitution of refined wheat flour with pomegranate peel powder (PPP) at a rate of 2%, 4%, 6%, 8% and 10% on the physico-chemical and sensorial properties as well as on the oxidative and microbial stability of muffins were investigated. RESULTS: A significant reduction in specific volume (1.99 to 1.57 cm3 g-1 ), weight loss (11.73 to 10.14 g 100 g-1 ) and an increase in crumb hardness (633.06 to 2311.5 g) of muffins were observed on addition of PPP. Moreover, the nutritional value was improved by a significant increase in the fiber content (4.39 to 10.66%), total phenols (0.443 to 48.53 mg GAE 100 g-1 ), antioxidant activity (75.94% to 99.36%), calcium (200.33 to 294.33 mg 100 g-1 ), potassium (227.33 to 425.33 mg 100 g-1 ) and magnesium (96.33 to 288.33 mg 100 g-1 ). The pasting and rheological properties of muffin batter showed a significant decrease in the final and peak viscosity, as well as increase in storage, loss and complex modulus. The muffin samples were organoleptically acceptable up to a level of 8% PPP. Free fatty acid content, peroxide value and microbial count of the muffin with 8% PPP were significantly lower compared to the control sample and more oxidatively and microbially stable for a storage period of 21 and 28 days at ambient and refrigerated temperatures, respectively. CONCLUSION: The present study provides the opportunity to use PPP as functional ingredients and natural preservative in the preparation of muffins. © 2023 Society of Chemical Industry.

Tubulin glutamylation regulates ciliary motility by altering inner dynein arm activity.

How microtubule-associated motor proteins are regulated is not well understood. A potential mechanism for spatial regulation of motor proteins is provided by posttranslational modifications of tubulin subunits that form patterns on microtubules. Glutamylation is a conserved tubulin modification [1] that is enriched in axonemes. The enzymes responsible for this posttranslational modification, glutamic acid ligases (E-ligases), belong to a family of proteins with a tubulin tyrosine ligase (TTL) homology domain (TTL-like or TTLL proteins) [2]. We show that in cilia of Tetrahymena, TTLL6 E-ligases generate glutamylation mainly on the B-tubule of outer doublet microtubules, the site of force production by ciliary dynein. Deletion of two TTLL6 paralogs caused severe deficiency in ciliary motility associated with abnormal waveform and reduced beat frequency. In isolated axonemes with a normal dynein arm composition, TTLL6 deficiency did not affect the rate of ATP-induced doublet microtubule sliding. Unexpectedly, the same TTLL6 deficiency increased the velocity of microtubule sliding in axonemes that also lack outer dynein arms, in which forces are generated by inner dynein arms. We conclude that tubulin glutamylation on the B-tubule inhibits the net force imposed on sliding doublet microtubules by inner dynein arms.

Tubulin polyglutamylase enzymes are members of the TTL domain protein family.

Polyglutamylation of tubulin has been implicated in several functions of microtubules, but the identification of the responsible enzyme(s) has been challenging. We found that the neuronal tubulin polyglutamylase is a protein complex containing a tubulin tyrosine ligase-like (TTLL) protein, TTLL1. TTLL1 is a member of a large family of proteins with a TTL homology domain, whose members could catalyze ligations of diverse amino acids to tubulins or other substrates. In the model protist Tetrahymena thermophila, two conserved types of polyglutamylases were characterized that differ in substrate preference and subcellular localization.