Preparation, characterisation and application of naturally derived polar lipids through lipolysis : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand

Monoglycerides are lipid based emulsifiers extensively used for their broad technical function in the food industry. Commercial monoglycerides are generally manufactured through chemical synthesis; however, lipolysis of triglycerides by lipase enzyme provides a biochemical pathway by which monoglycerides may be produced. This is particularly appealing for consumers for whom all natural and clean labelled food products are a particular driver. Accordingly, rather than replacing monoglycerides from formulations with other types of emulsifiers (and that may lack the requisite functionality), an alternative approach may be to develop a non-chemical and more natural pathway to produce the emulsifier, thereby allowing the particular monoglyceride functionality to be retained within products. Therefore, this study was conducted to investigate the feasibility of using lipase enzyme as a processing tool to synthesise polar lipids, namely monoglycerides, in situ of the manufacture of whippable food emulsions, such as cream and ice cream. This concept idea was initially proven viable through interfacial tension (IFT) measurements obtained using a straight-forward surface characterisation technique. R. miehei lipase was found to competitively bind at the interface of vegetable oils-water and that the adsorbed protein (sodium caseinate and whey protein isolate) or surfactant layer (lecithin and Tween 80) did not act as a barrier to lipase adsorption at the oil-water interface. IFT measurements were also able to demonstrate the progressive accumulation of polar lipids at the oil-water interface arising from lipolysis, and were additionally used to indicate how thermal treatment of the enzyme could be used to terminate activity. In considering how the requisite functionality could be achieved for whippable emulsion formulations, emulsion droplet size, type of emulsifiers used as well as lipase concentration were shown to be key variables by which the extent and rate of lipolysis could be manipulated and controlled. The results showed that formulation (emulsifier types and oil content) and processing conditions (Microfluidizer® pressure and number of passes) had significant effects on the emulsion droplet size. As part of controlling the extent of lipolysis, the conditions by which the reaction could be terminated were investigated by measuring the viability of R. miehei lipase against thermal treatment. Results showed that the R. miehei lipase was thermostable up to temperatures of 70 °C. Above this temperature, substantial reduction of the residual activity occurred. However, even elevated temperature of between 90 and 100 oC did not immediately inactivate the lipase, with heating for ~ 2 min required before activity was no longer detected. In terms of emulsion stability, the palm oil emulsion tested in this study was found to be thermostable up to 100 oC, thus allowing development of a thermalisation step that was able to inactivate the enzyme without compromising the stability of the emulsion. The shear stability analyses on lipolysed O/W emulsion showed the lipolysed emulsions were susceptible to shear-induced aggregation, and that the degree of aggregation could be manipulated as a consequence of controlling the extent of lipolysis through either enzyme concentration or holding time. The drastic increase in the viscosity curve between the nonlipolysed and lipolysed emulsion suggested that the shear–induced partial coalescence was primarily due to the lipolysis reaction and was not as a result of the high fat content (30 %). The findings elucidate the ability of the generated polar lipids in the emulsion to displace the existing sodium caseinate adsorbed layer, thus compromising emulsion stability upon shearing. The quantification of synthesised polar lipids from the triglyceride component of fat droplets by the lipolysis reaction showed a mixture of fatty acids, di- and mono-glycerides being produced. Palmitic acid was observed to be the main liberated fatty acids. While, monoolein and monopalmitin were the most prominent monoglycerides, with measured concentrations of 3.755 ± 0.895 and 1.660 ± 0.657 mg / g fat respectively after 15 min with lipase concentration of 50 mg /g fat. The relative concentration of polar lipids produced was found to be dependent on the lipase concentration as well as time of lipolysis. Furthermore, up to 30 min of lipolysis (concentration 50 mg /g fat) were seen to have no observable effect on the droplet size distribution of the emulsion suggesting that quiescently stable emulsions could be produced. The results show the importance of controlling reaction conditions (both enzyme concentration and reaction time) in order to provide requisite functionality without excessively destabilising emulsions such that droplet structuring can occur under quiescent conditions. The generation of monoglycerides at quantum satis levels able to impart critical functionality was demonstrated in whipped cream and ice cream. The addition of R. miehei lipase at very low concentration of 5 mg /g fat was able to produce a rigid and stable whipped cream with overrun exceeding 100 %. However, good stability of the whipped cream over time was achievable with concentration above 10 mg /g fat. Similarly, ice cream made with the addition of 5 mg /g fat exhibited good melt stability and firmness. The findings proved the feasibility of in situ production of polar lipids, namely monoglycerides and fatty acids, in replicating the functionality imparted by commercial monoglycerides in whippable emulsions. Thus, the findings in this thesis offer an alternative biochemical pathway for the generation of polar lipids to that of commercially available monoglycerides, which are currently produced synthetically. The potential for using this approach as part of the processing step for food emulsion manufacture has also been demonstrated. The concept can be tailored for various emulsion based food products

Effects Of Polyphenol And Ph On Cocoa Flavour Precursors And Flavour Compounds Using Lipidic Model System

Polyphenol is a naturally occurring compound in cocoa beans reported to reduce the concentration of flavour compounds, mainly pyrazines after cocoa roasting. This study was carried out to determine the effect of polyphenol concentrations and pH on cocoa flavour precursors (i.e. reducing sugars and amino acids) and flavour compounds (i.e. alkylpyrazines) during roasting. The study was conducted using a lipidic model system at roasting temperature 1200C for 45 min. The concentration of amino acids and reducing sugars incorporated in the model systems was based on the results of the concentration found in fermented Malaysian cocoa beans. To determine the effect of polyphenol concentration, crude polyphenol extracted from cocoa bean was added into the lipidic model system at 0, 58, 116 and 174 g kg-1. Results showed that the higher concentrations of polyphenols (174 g kg-1) significantly (p<0.05) decreased the concentration of reducing sugars and amino acids during roasting. As the concentration of polyphenol increased from 58, 116 to 174 g kg-1, fructose was degraded at 33, 35, and 41% and glucose at 29, 30 and 33% respectively. Seventeen individual amino acids were detected, among all; alanine, tyrosine, valine and isoleucine were significantly (p<0.05) degraded higher than the others. These amino acids which are in the hydrophobic group were degraded at 41, 44, 45 and 43 % respectively at polyphenol concentration 174 g kg-1. Changes in procyanidins monomeric and polymeric constituents were correlated with the reduction of the precursors. High polyphenol concentration (174 g kg-1) significantly decreased the formation of alkylpyrazines in the model system. The Response Surface Methodology (RSM) plots revealed that lower concentration of amino acids and reducing sugars was obtained at higher polyphenol concentration (120 g kg-1) and lower pH value (4.5). Based on the constraints set on the obtained surface plots, the optimum region for polyphenol concentration of 43 – 58 g kg-1 and pH of 7.0 -7.5 was obtained for the optimum production of flavour precursors; while the optimum region polyphenol concentration of 6.0 was obtained for the production of alkylpyrazines. The optimum point was determined using response optimizer and it was found that the optimum polyphenol concentration of 49.5 g kg-1 and pH of 7.2 for flavor precursors and polyphenol concentration of 52.3 g kg-1 and pH of 7.0 for generated alkypyrazines.Thus, it is recommended that the acidity of the beans should be controlled during processing and extracting the excessive amount of polyphenol higher than 52.3 g kg-1 from the cocoa beans should be considered to lower its negative effect on reducing sugars and amino acids

Functional properties of oleoresin extracted from white pepper (Piper nigrum L.) retting waste water

This study was carried out to determine the antioxidant activity, total phenolic content (TPC) and piperine in oleoresin extract of pepper retting waste water. Fresh pepper berries were soaked in distilled water (1:2 w/w) and allowed to ret at four different temperatures: 28, 35, 42 and 49°C for a total of 16 days. The retting waste water was collected on the 4th, 8th, 12th and 16th day and was then subjected to dichloromethane liquid extraction prior to analyses. The results showed that highest (p<0.05) oleoresin yield (271.34 ± 28.09 mg/g), antioxidant activity in DPPH (84.58 ± 4.93%), FRAP assay (49.55 ± 6.11 mM TE/g) and total phenolic content (5.64 ± 0.06 mg GAE/g) obtained at low temperature and shorter days of retting (28°C, day 4). Whilst at high temperature with longer days of retting (49°C, day 16) resulted in significantly higher (p<0.05) piperine content (1.81 ± 0.44%) in the waste water. Thus, the findings showed that the agro-industrial waste water produced during white pepper processing contain valuable bioactive oleoresins and other functional compounds which could be explored in details

Impact of date powder, sacha inchi oil, and moringa powder in a novel cognitive-enhancing health bar: an evaluation of physicochemical properties and functional benefits

Recent trends show a growing preference for healthy snacks in diets, particularly among health-conscious consumers, with snack bars gaining popularity among youth. This study aimed to develop and analyse a nutritious health bar to enhance cognitive performance. The health bar's formulation was created using design expert software. Comprehensive testing included proximate analysis, fatty acid profiling, and vitamin, mineral, and antioxidant evaluations, complemented by texture and colour assessments. Findings reveal these bars to be nutritionally rich, featuring excellent physical characteristics. They are notably abundant in essential fats (omega-3 and omega-6), vitamins, and minerals. The bars' high essential fat content, varied vitamin and mineral composition, and strong antioxidant properties align with the Recommended Nutrient Intakes (RNI) for Malaysian children and adolescents. This composition suggests that these health bars could effectively boost cognitive performance in this group

Kesan suhu pengekstrakan akueus terhadap ciri fizikokimia dan antioksidan gam bendi (Abelmoschus esculentus)

Penyelidikan ini dijalankan untuk menilai ciri fizikokimia gam bendi yang diekstrak pada suhu 25, 40, 60 dan 80 ℃. Ekstrak gam bendi kemudiannya dianalisis bagi penentuan pH, warna, kapasiti pengikat air, reologi dan kandungan fenol jumlah (TPC). Aktiviti antioksidan iaitu pemerangkapan radikal bebas 2,2-diferil-1-pikrihidrazil (DPPH) serta kuasa antioksidan penurunan ferik (FRAP) turut dijalankan. Hasil berat kering gam bendi menunjukkan tiada perbezaan signifikan (p>0.05) pada suhu pengekstrakan 25 ℃ dan 40 ℃. pH ekstrak gam bendi adalah hampir neutral (pH 6.69-6.75) pada suhu pengekstrakan 25 ℃ hingga 80 ℃, mempunyai warna yang cerah dan kuning kehijauan. Kapasiti pengikat air gam bendi yang diekstrak pada 25 ℃ dan 40 ℃ didapati lebih tinggi secara signifikan (p0.05). Kesimpulannya, peningkatan suhu pengekstrakan dapat meningkatkan hasil esktrak tetapi memberi kesan pengurangan kapasiti pengikat air serta kelikatan ketara ekstrak gam yang terhasil. Oleh itu, adalah penting untuk mengenal pasti objektif akhir penggunaan gam bendi bagi membolehkannya diekstrak menggunakan suhu yang paling sesuai dengan potensi penggunaannya

Cellulose powder from Piper nigrum L. agro-industrial waste: effect of preparation condition on chemical structure and thermal degradation

White pepper is generally produced via water retting process to decorticate the pericarp of green pepper. The decorticated pericarp is considered as an agro-industrial waste and environmental pollutant as many farmers still discard the waste into the rivers. These wastes majorly contain cellulose, hemicellulose, pectin, and other organic compound. Cellulose was obtained from alkaline treatment (4 wt. % sodium hydroxides, NaOH) followed by bleaching process. This study reports the effect of soaking cycle in bleaching treatment on the chemical structure and thermal degradation of cellulose. The cellulose obtained from pepper (Piper nigrum L.) pericarp waste were characterised by colour analysis, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Increased number of bleaching cycles produced a whiter colour and high thermal stability of cellulose powder. The whiteness index (WI) for high bleaching cycle sample was found significantly high (p<0.05) with the value of 77.00 ± 1.10. Thermal analysis indicates a derivative thermogravimetric analysis (DTG) peak at 332 °C. The FTIR spectrum proven that the condition of bleaching treatment changes the absorption intensity at bands 1732, 1540, and 1460 cm-1 which due to the loss of hemicellulose and lignin. The use of pepper pericarp waste that is usually discarded may provide a sustainable alternative for the production of cellulose

Pengoptimuman pengekstrakan lemak biji jeruk mangga (Mangifera indica L.) jeruk menggunakan kaedah respons permukaan dan analisis lipid

Sisa biji jeruk mangga (PMS) daripada industri jeruk mangga boleh meningkatkan kos pengeluaran dan pencemaran alam sekitar. Kajian terdahulu mendapati lemak biji mangga boleh dijadikan punca alternatif lemak koko (CBA) dalam penghasilan coklat. Oleh itu, penyelidikan ini dijalankan bagi mengetahui hasil ekstrak optimum lemak biji jeruk mangga (MPB) melalui tiga kaedah pengekstrakan iaitu maserasi, Soxhlet dan pengekstrakan bendalir lampau genting-karbon dioksida (SFE-CO2 ) dengan menggunakan kaedah respons permukaan-reka bentuk komposit berpusat (RSM-CCD). Keputusan parameter optimum adalah seperti berikut; maserasi (262 min, 100 mL heksana dengan 4.40% hasil); Soxhlet (300 min, 150 mL heksana dengan 7.87% hasil) dan SFE-CO2 (297 bar, 64 °C dengan 6.66% hasil). MPB yang diekstrak daripada semua kaedah dibandingkan dengan lemak koko komersial (CCB). MPB mengandungi asid lemak perlu (EFA) dan omega-3 yang tinggi serta lemak tepu yang rendah berbanding CCB. MPB ekstrak daripada SFE-CO2 mempunyai asid lemak dan profil pencairan yang hampir sama dengan CCB. SFE-CO2 juga mengekstrak lebih banyak EFA dan omega-3 (p<0.05) daripada maserasi dan Soxhlet. Oleh itu, MPB ekstrak daripada SFE-CO2 berpotensi sebagai punca CBA yang terbaik dalam penghasilan coklat

Assessment of natural cellulosic powder from pepper pericarp waste (Piper nigrum L.) after alkalization and bleaching treatment : effect of alkali concentration and treatment cycle

Pepper (Piper nigrum L.) pericarp is an agriculture waste in the production of white pepper. It is underutilised agro-industrial waste which could be a promising natural source of cellulose. Hence, finding an optimum way to remove the non cellulose components without degrading the cellulose structure is essential. In this work, the effects of alkaline concentration (4, 5, and 6% NaOH) and number of soaking cycle (3 & 4 cycles) on the characteristics of cellulose from pepper pericarp were investigated. The obtained cellulose powder was characterized for its yield, α-cellulose content, particle size, zeta potential, morphology, whiteness index, crystallinity degree and thermal stability. The white powder cellulose after 4th cycle treatment with 4% NaOH appeared to have the highest yield (23.63%), α-cellulose (65.97%), crystallinity structure (51%) and better thermal stability at 334 °C. FTIR spectrum at band around 1732 cm-1 indicates a partial removal of non-cellulosic material at all alkalization condition due to the presence of remaining lignin and hemicellulose. These may contribute to formation of negative surface charge on all cellulose samples which may potentially enhance the functionality of the material as emulsifier. Based on two-way ANOVA test, concentration and cycle of alkaline treatment significantly (p<0.05) influenced the yield, particle size and zeta potential, meanwhile α-cellulose significantly influence by NaOH concentration only (p<0.05). The findings showed that manipulating the synthesis condition of cellulose powder influenced its properties which could be further used in various applications

Kesan kaedah pengeringan dan pelarut yang berbeza terhadap kandungan fenol, aktiviti antioksidan dan antihiperglisemik ekstrak rizom halia hutan (Alpinia mutica Roxb.)

Alpinia mutica Roxb. (Zingiberaceae), juga dikenali sebagai halia hutan ialah sejenis tumbuhan yang kaya dengan sumber bahan bioaktif, berupaya menentang sel kanser dan berpotensi untuk bertindak sebagai agen antioksidan. Kajian ini dijalankan untuk mengkaji kesan kaedah pengeringan (pengeringan ketuhar (PK) dan sejuk beku (PB)) serta penggunaan campuran pelarut etanol dan air pada nisbah yang berbeza (100:0, 50:50 dan 0:100) terhadap kandungan fenol, aktiviti antioksidan dan antihiperglisemik ekstrak rizom A. mutica (ERA). Kandungan fenol ERA dikaji dengan ujian penentuan Jumlah Kandungan Fenol (TPC) manakala aktiviti antioksidan ditentukan dengan Ujian Aktiviti Penyingkiran Radikal Bebas (DPPH) dan Ujian Kuasa Penurunan Ferik (FRAP). Aktiviti antihiperglisemik dikaji melalui perencatan enzim α-glukosidase. Hasil kajian ini menunjukkan bahawa penggunaan kaedah pengeringan dan pelarut yang berbeza mempengaruhi kandungan fenol, aktiviti antioksidan dan kesan antihiperglisemik ERA. Sampel PK yang diekstrak dengan nisbah pelarut 100:0 menunjukkan aktiviti antioksidan (DPPH) dan kesan antihiperglisemik yang terbaik dengan nilai kepekatan perencatan separuh maksimum (IC50) yang paling rendah, 550.94 ± 50.02 dan 84.97 ± 11.69 μg/mL. Sampel PK (100:0) juga mencatatkan kandungan fenol (155.55 ± 9.36 mg GAE/g ekstrak) dan nilai FRAP (108.98 ± 10.08 mg TEAC/g ekstrak) yang tertinggi dengan perbezaan yang ketara berbanding dengan sampel lain (p < 0.05). Korelasi positif antara TPC dengan aktiviti antioksidan dan antihiperglisemik menunjukkan kebarangkalian bahawa sebatian fenol ialah komponen yang bertanggungjawab terhadap aktiviti biologi yang diperoleh. Hasil kajian ini menunjukkan bahawa teknik pengeringan dan nisbah pelarut ekstrak yang digunakan jelas mempengaruhi kandungan fenol, aktiviti antioksidan dan kesan antihiperglisemik (ERA)

Kesan penambahan Gam Bendi (Abelmoschus esculentus) pada emulsi minyak dalam air

Kajian ini dilakukan untuk menentukan kesan penambahan gam bendi (Abelmoschus esculentus) ke atas emulsi minyak dalam air. Gam bendi diperolehi melalui pengekstrakan akueus dan dikering bekukan sebelum dilarutkan semula mengikut kepekatan yang dikehendaki. Minyak kelapa sawit (20%) digunakan bagi membentuk emulsi minyak dalam air dengan penambahan isolat protein wei (1%) sebagai pengemulsi. Sebanyak 0.0, 0.5, 1.0, 2.0 dan 3.0% ditambah ke dalam formulasi emulsi yang dihasilkan. Analisis fizikokimia yang digunakan sebagai respons ialah ujian kelikatan, kadar pengkriman dan kadar penyingkiran protein permukaan. Emulsi kawalan yang distabilkan menggunakan protein wei (kawalan) adalah stabil sehingga hari ke-5 tanpa pengkriman secara signifikan (p>0.05). Walau bagaimanapun, pengkriman berlaku pada hari ke 7 dan bertambah secara signifikan (p<0.05) pada hari ke 10. Penambahan gam bendi pada kepekatan tinggi iaitu 2.0 dan 3.0% didapati membantu mengekalkan kestabilan emulsi minyak dalam air. Sampel kawalan mempunyai kelikatan yang paling rendah. Penambahan gam bendi dilihat menyebabkan kelikatan emulsi minyak dalam air yang dihasilkan juga bertambah mengikut kepekatan gam bendi yang digunakan. Terdapat peningkatan penyahjerapan protein daripada permukaan antara minyak dan air yang diakibatkan oleh penambahan gam bendi. Fenomena ini kelihatan lebih cenderung berlaku pada kepekatan gam bendi yang lebih rendah (0.5 dan 1.0%). Oleh yang demikian, gam bendi berpotensi digunakan di dalam produk berasaskan emulsi untuk meningkatkan kelikatan dan kestabilan terhadap pengkriman