UNIVERSITÀ DEGLI STUDI DI PADOVA Sede Amministrativa: Università degli Studi di Padova DIPARTIMENTO DI AGRONOMIA ANIMALI ALIMENTI RISORSE NATURALI E AMBIENTE - DAFNAE SCUOLA DI DOTTORATO DI RICERCA IN SCIENZE ANIMALI E AGROALIMENTARI INDIRIZZO SCIENZE ANIMALI CICLO XXVI FUNCTIONAL MEAT AND MEAT PRODUCTS FROM UNCONVENTIONAL MEAT SPECIES Direttore della Scuola : Ch.mo Prof. Martino Cassandro Coordinatore d’indirizzo: Ch.mo Prof. Roberto Mantovani Supervisore: Ch.ma Prof.ssa Antonella Dalle Zotte Dottorando : Marco Cullere 2 Alla mia famiglia e a Mara… 3 4 TABLE OF CONTENTS The outline of the thesis 6 Abstract 8 Riassunto 10 Chapter 1 General introduction 12 Chapter 2 General aims 66 Chapter 3 Effects of Dietary supplementation of Spirulina (Arthrospira platensis) and Thyme (Thymus vulgaris) to growing rabbits on: a) Apparent digestibility and productive performances of growing rabbits 68 b) Carcass composition, meat physical traits, and vitamin B12 content on growing rabbits 85 c) Rabbit meat appearance, oxidative stability and fatty acid profile during retail display 104 d) Raw and cooked meat quality, nutrient true retention and oxidative stability 123 Chapter 4 Oregano, Rosemary, Vitamin E and Saccaromyces cerevisiae dietary supplementation to growing rabbits: Effect on growth performance, carcass traits, bone development and meat chemical composition 155 Chapter 5 First evaluation of unfermented and fermented rooibos (Aspalathus linearis) in preventing lipid oxidation in ostrich meat products 173 Chapter 6 Two different fat inclusion levels, NaCl contents and two LAB starter cultures in the manufacturing of Italian-type ostrich salami ripened for 10 and 20 weeks: Part 1. Weight loss, proximate composition and cholesterol content 193 Chapter 7 General conclusions 216 List of publications 218 5 6 THE OUTLINE OF THE THESIS In the first part, some topics to understand and contextualize the research of the present PhD thesis are presented (Chapter 1). Initially, a brief description the role of meat in human evolution and nutrition, as well as the risks and benefits derived from its consumption is provided. Subsequently, one of the most problematic issues concerning meat quality and the possible remedies to prevent it are depicted: lipid oxidation and antioxidants. Then, after describing the history, meaning and role of functional meat and meat products, the two meat species used for the research are presented: the ostrich and the rabbit. In Chapter 2, the general aims of four main contributes are provided: Chapter 3, which includes four different subchapters, and Chapter 4 deal with dietary strategies to improve rabbit meat quality. Chapter 5 and 6 approach two possible complimentary interventions to reduce some compounds or incorporate functional ingredients in ostrich fresh meat as well as processed meat products. The first three subchapters of Chapter 3 (a, b and c) and Chapter 5 have been already published in peer reviewed scientific journals, whereas Chapter 3d, Chapter 4 and 6 have been submitted to peer reviewed scientific papers. The last part of the present thesis (Chapter 7), provides the general conclusions of the research work. Figure 1 graphically shows the contents and organization of the present thesis. 7 Figure 1. The outline of the thesis Chapter 1: Introduction Chapter 2: General aims Chapter 3: Effect of Spirulina (Arthrospira platensis) and Thyme (Thymus vulgaris) dietary supplementation to the diet of growing rabbits on: Part a) Growth performance, health status and apparent digestibility Part b) Carcass composition, meat physical traits and vitamin B12 content Part c) Oxidative stability under retail conditions Part d) Raw and cooked meat quality, nutrient true retention and oxidative stability Chapter 4: Oregano, rosemary, vitamin E and Saccaromyces cerevisiae dietary supplementation to growing rabbits: Effect on growth performance, carcass traits, bone development and meat chemical composition Chapter 5: First evaluation of unfermented and fermented rooibos (Aspalathus linearis) in preventing lipid oxidation of ostrich meat products Chapter 6: Effect of different NaCl and fat contents, microbial starter culture and ripening time on proximate composition, cholesterol content and cumulative weight loss during ripening of Italian style ostrich salami Chapter 7: General conclusions List of publications 8 ABSTRACT The present thesis, which includes four main researches, aimed to study functional meat and meat products obtained from unconventional meat species, namely the rabbit and the ostrich. The first research tested the single and combined dietary supplementation with 5% Spirulina (Arthrospira platensis) and 3% Thyme (Thymus vulgaris) to growing rabbits for 3 and 6 weeks, and it is articulated in four different subchapters. The first subchapter considered the effect on total tract apparent digestibility of nutrients and on the performances of growing rabbits and showed that that single and combined supplementation with Spirulina reduced the nutritive value of the diets. Despite this, no substantial effect on growth performance and health status, was observed. Future studies should take into consideration feed processing technology, pelleting, storage and packaging conditions, as they may reduce or nullify the nutrient and functional compounds‘ availability. Moreover, Spirulina and/or Thyme effect on health status should be tested under poorer sanitary conditions. The second subchapter studied the effects on growing rabbit carcass composition, meat and bone rheological traits, and the vitamin B12 content of Longissimus dorsi (LD) meat. Spirulina was confirmed as a rich source of vitamin B12 that was successfully transferred into LD meat, thus demonstrating its value as an effective natural supplement in producing food fortified with this vital element. With this exception, the supplement as well as and the duration of treatment had no effect on the considered traits. The third subchapter evaluated the effect on rabbit meat during retail display. Thyme improved colour parameters and reduced exudative losses during a simulated retail display, also considering a shorter supplementation period. This would positively impact consumers at the time of purchase as well as farmers demand to limit production costs. Differently, Spirulina had no effect on oxidative stability of rabbit meat, maybe for the poor absorption from the gut as a result of interference on uptake of antioxidants by Spirulina, or maybe because dietary level of Spirulina was not adequate for rabbits requirements. The fourth subchapter studied the effects on raw and cooked rabbit meat quality, nutrient true retention and protection against oxidative stress conditions. The dietary inclusion of Spirulina improved the FA profile of the Longissimus dorsi and hind leg meat by significantly increasing γ-linolenic acid content. Thyme improved the oxidative stability of raw and freeze-dried HL meat but not that of cooked meat. 9 As for the shelf-life trial, Spirulina was not observed to improve the oxidative stability of rabbit meat subjected to severe oxidative stress. The second research of the present thesis, aimed to evaluate the effect of the dietary single or combined supplementation with different natural additives (Oregano, Rosemary, vitamin E and Saccaromyces cerevisiae) on the performance of growing rabbits, the nutritional composition and oxidative stability of their meat and on their hind leg bone traits. The results of this research demonstrated that an adequate supplementation with natural antioxidants can also have a positive effect on productive performance and meat quality. The fifth chapter evaluated, for the first time, the unfermented and fermented rooibos (Aspalathus linearis) in preventing lipid oxidation in ostrich meat patties and ostrich salami. This plant showed interesting and promising antioxidant potential when applied to meat products, even if further study are necessary to deeply investigate long-term effects. The sixth chapter studied the effect of two different fat inclusion levels, NaCl contents and two LAB starter cultures on the weight loss, proximate composition and cholesterol content of ostrich salami ripened for 10 and 20 weeks. A lower fat content consistently shortened ripening time, thus being a positive aspect in terms of productivity, and it determined a higher nutrients concentration compared to high fat salami. Reducing the NaCl inclusion, retarded the weight loss of the product of about 1 week, without affecting its proximate composition. Finally, the metabolic activity of tested LAB starter cultures seemed to be influenced by the fat inclusion level, ultimately affecting the healthiness of the products at 10 weeks of ripening. 10 RIASSUNTO La presente tesi si compone di quattro ricerche principali e si propone di studiare carne e prodotti carnei funzionali ottenuti da specie non convenzionali, lo struzzo e il coniglio. La prima ricerca ha testato l‘inclusione singola o combinata, per 3 o 6 settimane, con il 5% di Spirulina (Arthrospira platensis) ed il 3% di Timo (Thymus vulgaris) nella dieta di conigli in accrescimento. Questo primo capitolo si articola in quattro sottocapitoli. Il primo ha considerato l‘effetto sulla digeribilità apparente delle diete e sulle prestazioni produttive di conigli in accrescimento e ha evidenziato che l‘inclusione separata o combinata di Spirulina ha ridotto il valore nutritivo delle diete. Nonostante ciò, non è stato osservato alcun effetto sulle prestazioni produttive